<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:6b8c0011-9ea2-4a95-afff-75f2e823f429,g:f607995d-2988-4506-9f40-b72871c32d7c-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.pentair.com/role/ConsolidatedStatementsofChangesInEquity" xlink:type="simple" xlink:href="pnr-20231231.xsd#ConsolidatedStatementsofChangesInEquity"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/ConsolidatedStatementsofChangesInEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_2c007c70-c1ce-445c-bd39-90c2bb19dbb7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_StatementTable_2c007c70-c1ce-445c-bd39-90c2bb19dbb7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_2079f0c7-a5c0-4601-be65-0b775b658ebd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_2c007c70-c1ce-445c-bd39-90c2bb19dbb7" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_2079f0c7-a5c0-4601-be65-0b775b658ebd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_2079f0c7-a5c0-4601-be65-0b775b658ebd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2079f0c7-a5c0-4601-be65-0b775b658ebd" xlink:to="loc_us-gaap_EquityComponentDomain_2079f0c7-a5c0-4601-be65-0b775b658ebd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_f21fc109-d76b-4ca1-b6d2-4a9c14c8e2d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2079f0c7-a5c0-4601-be65-0b775b658ebd" xlink:to="loc_us-gaap_EquityComponentDomain_f21fc109-d76b-4ca1-b6d2-4a9c14c8e2d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_05640e9d-4f52-4b38-ab07-6d7bbe327816" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_f21fc109-d76b-4ca1-b6d2-4a9c14c8e2d8" xlink:to="loc_us-gaap_CommonStockMember_05640e9d-4f52-4b38-ab07-6d7bbe327816" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_bc936628-3e95-4877-b6fb-0fe928281757" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_f21fc109-d76b-4ca1-b6d2-4a9c14c8e2d8" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_bc936628-3e95-4877-b6fb-0fe928281757" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_df5e446b-29d6-42c3-9351-01d08e4f5079" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_f21fc109-d76b-4ca1-b6d2-4a9c14c8e2d8" xlink:to="loc_us-gaap_RetainedEarningsMember_df5e446b-29d6-42c3-9351-01d08e4f5079" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_70a33596-cc56-4def-8c5e-a2bb8e58c99c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_f21fc109-d76b-4ca1-b6d2-4a9c14c8e2d8" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_70a33596-cc56-4def-8c5e-a2bb8e58c99c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_9d41cd3e-c37b-4b27-898e-d3361b8bd6df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_SharesOutstanding_9d41cd3e-c37b-4b27-898e-d3361b8bd6df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_e4edad7a-6584-46a9-b50b-d6848ca90dcb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_e4edad7a-6584-46a9-b50b-d6848ca90dcb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_5891b5b2-0978-438c-9943-91293615c684" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_ProfitLoss_5891b5b2-0978-438c-9943-91293615c684" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_0b4f1b1c-dda9-44c6-8f19-f8e108f07e3c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_0b4f1b1c-dda9-44c6-8f19-f8e108f07e3c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStock_4b044718-8e10-4360-a974-926aa2a04cc4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_DividendsCommonStock_4b044718-8e10-4360-a974-926aa2a04cc4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_f3aeb83e-031a-45e0-831f-8cefeb87a780" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_f3aeb83e-031a-45e0-831f-8cefeb87a780" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_196303c0-06df-4d83-bb73-02642313be48" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_196303c0-06df-4d83-bb73-02642313be48" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_7bbd7637-5daa-4ad4-a5d5-0b1f8a1c12e9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_7bbd7637-5daa-4ad4-a5d5-0b1f8a1c12e9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_b2f431ee-a94f-4670-bda6-162ce436afa9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_b2f431ee-a94f-4670-bda6-162ce436afa9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_4c975cc4-cf36-4d93-82b6-b7a84a47f1a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_4c975cc4-cf36-4d93-82b6-b7a84a47f1a3" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_0fdfb396-7ebc-4aee-9f11-3c0d70db9a07" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_0fdfb396-7ebc-4aee-9f11-3c0d70db9a07" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SharesSurrenderedByEmployeesShares_fe98b507-2577-40f0-81eb-39cd98d07735" xlink:href="pnr-20231231.xsd#pnr_SharesSurrenderedByEmployeesShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_pnr_SharesSurrenderedByEmployeesShares_fe98b507-2577-40f0-81eb-39cd98d07735" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SharesSurrenderedByEmployees_8e4c2731-d1c4-4c0d-8dba-2f6d6f482f20" xlink:href="pnr-20231231.xsd#pnr_SharesSurrenderedByEmployees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_pnr_SharesSurrenderedByEmployees_8e4c2731-d1c4-4c0d-8dba-2f6d6f482f20" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_8008d8e4-bbe7-4dc2-b2ca-7ff2f40ae04f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e583e6c1-ca6a-40df-830c-762357a46fd0" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_8008d8e4-bbe7-4dc2-b2ca-7ff2f40ae04f" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_6250c616-c61f-4c6e-a41e-d544f015f900" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_306ab1c4-307f-4723-a9e0-0e93966ac81a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesBasisofPresentationDetails" xlink:type="simple" xlink:href="pnr-20231231.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesBasisofPresentationDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesBasisofPresentationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_9503f254-b3af-430f-93b0-98b5e72cf6ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_26b8b6f8-3297-43f5-accc-b3dee68a64a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_9503f254-b3af-430f-93b0-98b5e72cf6ea" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_26b8b6f8-3297-43f5-accc-b3dee68a64a1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ac05cde3-e1d5-4712-85ba-657777e89789" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_26b8b6f8-3297-43f5-accc-b3dee68a64a1" xlink:to="loc_srt_RangeAxis_ac05cde3-e1d5-4712-85ba-657777e89789" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ac05cde3-e1d5-4712-85ba-657777e89789_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ac05cde3-e1d5-4712-85ba-657777e89789" xlink:to="loc_srt_RangeMember_ac05cde3-e1d5-4712-85ba-657777e89789_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_98a734bb-1ff2-4d00-991c-7c8b4b31a440" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ac05cde3-e1d5-4712-85ba-657777e89789" xlink:to="loc_srt_RangeMember_98a734bb-1ff2-4d00-991c-7c8b4b31a440" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_f5180684-575b-4965-807f-a5f8bc0b120a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_98a734bb-1ff2-4d00-991c-7c8b4b31a440" xlink:to="loc_srt_MinimumMember_f5180684-575b-4965-807f-a5f8bc0b120a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_db454760-c4c3-4338-9181-55aef9cd122d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_98a734bb-1ff2-4d00-991c-7c8b4b31a440" xlink:to="loc_srt_MaximumMember_db454760-c4c3-4338-9181-55aef9cd122d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_c49fe8ae-f8d2-4155-8c75-c4e5db448abc" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_26b8b6f8-3297-43f5-accc-b3dee68a64a1" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_c49fe8ae-f8d2-4155-8c75-c4e5db448abc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_c49fe8ae-f8d2-4155-8c75-c4e5db448abc_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_c49fe8ae-f8d2-4155-8c75-c4e5db448abc" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_c49fe8ae-f8d2-4155-8c75-c4e5db448abc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_e3f18b4b-db2d-443c-98df-7d2d800555ef" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_c49fe8ae-f8d2-4155-8c75-c4e5db448abc" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_e3f18b4b-db2d-443c-98df-7d2d800555ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_InvesteesOtherMember_61387782-b8ea-4133-94e4-6213cea681ae" xlink:href="pnr-20231231.xsd#pnr_InvesteesOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_e3f18b4b-db2d-443c-98df-7d2d800555ef" xlink:to="loc_pnr_InvesteesOtherMember_61387782-b8ea-4133-94e4-6213cea681ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_277c874f-f667-4094-9e59-510ca36e2920" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_9503f254-b3af-430f-93b0-98b5e72cf6ea" xlink:to="loc_us-gaap_NumberOfReportableSegments_277c874f-f667-4094-9e59-510ca36e2920" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_9be26afe-c647-49f2-b9a5-c7b1f415c58d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_9503f254-b3af-430f-93b0-98b5e72cf6ea" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_9be26afe-c647-49f2-b9a5-c7b1f415c58d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesRevenueAdditionalInformationDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesRevenueAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesRevenueAdditionalInformationDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_3f3bfbfa-d821-4294-909c-133ca86cc03e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_58a08dc6-84a8-4a2d-8327-0865c6bfc2ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3f3bfbfa-d821-4294-909c-133ca86cc03e" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_58a08dc6-84a8-4a2d-8327-0865c6bfc2ee" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_c1400d7a-2cc6-483b-a6b7-a4a7d62f63a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TimingOfTransferOfGoodOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_58a08dc6-84a8-4a2d-8327-0865c6bfc2ee" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_c1400d7a-2cc6-483b-a6b7-a4a7d62f63a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_c1400d7a-2cc6-483b-a6b7-a4a7d62f63a9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_c1400d7a-2cc6-483b-a6b7-a4a7d62f63a9" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_c1400d7a-2cc6-483b-a6b7-a4a7d62f63a9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_53d7eb0c-5fb2-4910-9227-d36d0c896a2e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_c1400d7a-2cc6-483b-a6b7-a4a7d62f63a9" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_53d7eb0c-5fb2-4910-9227-d36d0c896a2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredAtPointInTimeMember_0761e2cb-6277-44ff-b387-203dee23c8db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransferredAtPointInTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_53d7eb0c-5fb2-4910-9227-d36d0c896a2e" xlink:to="loc_us-gaap_TransferredAtPointInTimeMember_0761e2cb-6277-44ff-b387-203dee23c8db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredOverTimeMember_7f8b974d-b1b8-4b65-8c8f-1427d3dd8c93" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransferredOverTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_53d7eb0c-5fb2-4910-9227-d36d0c896a2e" xlink:to="loc_us-gaap_TransferredOverTimeMember_7f8b974d-b1b8-4b65-8c8f-1427d3dd8c93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetCreditLossExpense_a5cfdab0-a34f-4dbf-8f73-a193bce2f166" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerAssetCreditLossExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3f3bfbfa-d821-4294-909c-133ca86cc03e" xlink:to="loc_us-gaap_ContractWithCustomerAssetCreditLossExpense_a5cfdab0-a34f-4dbf-8f73-a193bce2f166" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_1f5707e4-498d-4343-bd6c-06e5208eee72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3f3bfbfa-d821-4294-909c-133ca86cc03e" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_1f5707e4-498d-4343-bd6c-06e5208eee72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_RevenuesPercent_d2a97488-2e92-4646-9094-7994c5a76ce9" xlink:href="pnr-20231231.xsd#pnr_RevenuesPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3f3bfbfa-d821-4294-909c-133ca86cc03e" xlink:to="loc_pnr_RevenuesPercent_d2a97488-2e92-4646-9094-7994c5a76ce9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_e4d8e156-7356-46cf-a568-8a60921abd75" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3f3bfbfa-d821-4294-909c-133ca86cc03e" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_e4d8e156-7356-46cf-a568-8a60921abd75" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_66d969ba-9906-40a7-93ed-0616f55de1c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3f3bfbfa-d821-4294-909c-133ca86cc03e" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_66d969ba-9906-40a7-93ed-0616f55de1c0" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesPerformanceObligationsDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesPerformanceObligationsDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesPerformanceObligationsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a5ba1409-32e4-4a5e-94c9-1029bf29030c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_e30aa727-b500-46b3-a9dd-7ccff9abc247" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a5ba1409-32e4-4a5e-94c9-1029bf29030c" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_e30aa727-b500-46b3-a9dd-7ccff9abc247" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_58de1a21-9263-4c20-baba-504d5a785a87" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_e30aa727-b500-46b3-a9dd-7ccff9abc247" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_58de1a21-9263-4c20-baba-504d5a785a87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_fdda2f75-c7b8-4b18-8129-7d6f36df9706" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_e30aa727-b500-46b3-a9dd-7ccff9abc247" xlink:to="loc_srt_RangeAxis_fdda2f75-c7b8-4b18-8129-7d6f36df9706" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_fdda2f75-c7b8-4b18-8129-7d6f36df9706_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_fdda2f75-c7b8-4b18-8129-7d6f36df9706" xlink:to="loc_srt_RangeMember_fdda2f75-c7b8-4b18-8129-7d6f36df9706_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c1d6deae-9d79-47f9-b445-dfd8564d675e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_fdda2f75-c7b8-4b18-8129-7d6f36df9706" xlink:to="loc_srt_RangeMember_c1d6deae-9d79-47f9-b445-dfd8564d675e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_cf7bea77-b047-4c6d-a6e5-7d681f31377d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c1d6deae-9d79-47f9-b445-dfd8564d675e" xlink:to="loc_srt_MinimumMember_cf7bea77-b047-4c6d-a6e5-7d681f31377d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_2fe7e745-f306-463b-9f1d-1ef5e2bd2ed7" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c1d6deae-9d79-47f9-b445-dfd8564d675e" xlink:to="loc_srt_MaximumMember_2fe7e745-f306-463b-9f1d-1ef5e2bd2ed7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_fb9922a0-0528-4a05-97c6-b58bb3645981" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a5ba1409-32e4-4a5e-94c9-1029bf29030c" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_fb9922a0-0528-4a05-97c6-b58bb3645981" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_1d82c9db-604d-4c77-b661-037a797b76a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a5ba1409-32e4-4a5e-94c9-1029bf29030c" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_1d82c9db-604d-4c77-b661-037a797b76a0" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesPerformanceObligationsDetail_1" xlink:type="simple" xlink:href="pnr-20231231.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesPerformanceObligationsDetail_1"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesPerformanceObligationsDetail_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a5ba1409-32e4-4a5e-94c9-1029bf29030c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_e30aa727-b500-46b3-a9dd-7ccff9abc247" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a5ba1409-32e4-4a5e-94c9-1029bf29030c" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_e30aa727-b500-46b3-a9dd-7ccff9abc247" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_fdda2f75-c7b8-4b18-8129-7d6f36df9706" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_e30aa727-b500-46b3-a9dd-7ccff9abc247" xlink:to="loc_srt_RangeAxis_fdda2f75-c7b8-4b18-8129-7d6f36df9706" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_fdda2f75-c7b8-4b18-8129-7d6f36df9706_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_fdda2f75-c7b8-4b18-8129-7d6f36df9706" xlink:to="loc_srt_RangeMember_fdda2f75-c7b8-4b18-8129-7d6f36df9706_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c1d6deae-9d79-47f9-b445-dfd8564d675e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_fdda2f75-c7b8-4b18-8129-7d6f36df9706" xlink:to="loc_srt_RangeMember_c1d6deae-9d79-47f9-b445-dfd8564d675e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_cf7bea77-b047-4c6d-a6e5-7d681f31377d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c1d6deae-9d79-47f9-b445-dfd8564d675e" xlink:to="loc_srt_MinimumMember_cf7bea77-b047-4c6d-a6e5-7d681f31377d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_2fe7e745-f306-463b-9f1d-1ef5e2bd2ed7" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c1d6deae-9d79-47f9-b445-dfd8564d675e" xlink:to="loc_srt_MaximumMember_2fe7e745-f306-463b-9f1d-1ef5e2bd2ed7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_fb9922a0-0528-4a05-97c6-b58bb3645981" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a5ba1409-32e4-4a5e-94c9-1029bf29030c" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_fb9922a0-0528-4a05-97c6-b58bb3645981" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_1d82c9db-604d-4c77-b661-037a797b76a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a5ba1409-32e4-4a5e-94c9-1029bf29030c" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_1d82c9db-604d-4c77-b661-037a797b76a0" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNetSalesInformationDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesNetSalesInformationDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNetSalesInformationDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_08c01ed4-0a83-4e4c-b387-ba38ce97c6f0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_d722c65f-c487-4625-8498-4907e7f1cb5e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_08c01ed4-0a83-4e4c-b387-ba38ce97c6f0" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_d722c65f-c487-4625-8498-4907e7f1cb5e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_de3d965e-fbb5-47c8-9c73-8cb0e1a9aa74" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_d722c65f-c487-4625-8498-4907e7f1cb5e" xlink:to="loc_srt_StatementGeographicalAxis_de3d965e-fbb5-47c8-9c73-8cb0e1a9aa74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_de3d965e-fbb5-47c8-9c73-8cb0e1a9aa74_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_de3d965e-fbb5-47c8-9c73-8cb0e1a9aa74" xlink:to="loc_srt_SegmentGeographicalDomain_de3d965e-fbb5-47c8-9c73-8cb0e1a9aa74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_d65ebd09-85d8-45d1-982a-3512ad9e5bd1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_de3d965e-fbb5-47c8-9c73-8cb0e1a9aa74" xlink:to="loc_srt_SegmentGeographicalDomain_d65ebd09-85d8-45d1-982a-3512ad9e5bd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_8bb42221-1ba2-4f85-8ba1-1574edfef2c6" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_d65ebd09-85d8-45d1-982a-3512ad9e5bd1" xlink:to="loc_country_US_8bb42221-1ba2-4f85-8ba1-1574edfef2c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_WesternEuropeMember_1a640676-1cb7-4955-9604-96f512023336" xlink:href="pnr-20231231.xsd#pnr_WesternEuropeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_d65ebd09-85d8-45d1-982a-3512ad9e5bd1" xlink:to="loc_pnr_WesternEuropeMember_1a640676-1cb7-4955-9604-96f512023336" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DevelopingCountriesMember_280e4194-9d1b-4b71-a62d-7e44211a9ff6" xlink:href="pnr-20231231.xsd#pnr_DevelopingCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_d65ebd09-85d8-45d1-982a-3512ad9e5bd1" xlink:to="loc_pnr_DevelopingCountriesMember_280e4194-9d1b-4b71-a62d-7e44211a9ff6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_OtherDevelopedCountriesMember_756bd702-e1e7-47cf-8900-473990f4a258" xlink:href="pnr-20231231.xsd#pnr_OtherDevelopedCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_d65ebd09-85d8-45d1-982a-3512ad9e5bd1" xlink:to="loc_pnr_OtherDevelopedCountriesMember_756bd702-e1e7-47cf-8900-473990f4a258" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesByIndustryAxis_004526d0-fae6-454b-856b-74b841e51b11" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_d722c65f-c487-4625-8498-4907e7f1cb5e" xlink:to="loc_us-gaap_EquitySecuritiesByIndustryAxis_004526d0-fae6-454b-856b-74b841e51b11" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_004526d0-fae6-454b-856b-74b841e51b11_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_004526d0-fae6-454b-856b-74b841e51b11" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_004526d0-fae6-454b-856b-74b841e51b11_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_0b14633b-6a79-4397-84c0-489115df8c2f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_004526d0-fae6-454b-856b-74b841e51b11" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_0b14633b-6a79-4397-84c0-489115df8c2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ResidentialSectorMember_80bd35e8-79c0-45c7-9b9c-05c9a69dac3f" xlink:href="pnr-20231231.xsd#pnr_ResidentialSectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_0b14633b-6a79-4397-84c0-489115df8c2f" xlink:to="loc_pnr_ResidentialSectorMember_80bd35e8-79c0-45c7-9b9c-05c9a69dac3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_CommercialSectorMember_2ca6c370-6e44-46e5-9093-5429053c6a3b" xlink:href="pnr-20231231.xsd#pnr_CommercialSectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_0b14633b-6a79-4397-84c0-489115df8c2f" xlink:to="loc_pnr_CommercialSectorMember_2ca6c370-6e44-46e5-9093-5429053c6a3b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_IndustrialSectorMember_aa419b81-4ad7-40d5-ad3c-5c6846228bfd" xlink:href="pnr-20231231.xsd#pnr_IndustrialSectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_0b14633b-6a79-4397-84c0-489115df8c2f" xlink:to="loc_pnr_IndustrialSectorMember_aa419b81-4ad7-40d5-ad3c-5c6846228bfd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_95f542d2-c810-4c59-bc83-288579297d89" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_08c01ed4-0a83-4e4c-b387-ba38ce97c6f0" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_95f542d2-c810-4c59-bc83-288579297d89" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesEstimatedUsefulLivesofPropertyandEquipmentDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesEstimatedUsefulLivesofPropertyandEquipmentDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesEstimatedUsefulLivesofPropertyandEquipmentDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c19119e1-f552-4b16-b7d6-554ed7873edf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_d0590794-40cd-42f7-8c51-da56b14abe7d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c19119e1-f552-4b16-b7d6-554ed7873edf" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_d0590794-40cd-42f7-8c51-da56b14abe7d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_229148b7-6da5-4472-bb91-21766a7bfa43" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_d0590794-40cd-42f7-8c51-da56b14abe7d" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_229148b7-6da5-4472-bb91-21766a7bfa43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_229148b7-6da5-4472-bb91-21766a7bfa43_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_229148b7-6da5-4472-bb91-21766a7bfa43" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_229148b7-6da5-4472-bb91-21766a7bfa43_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4fb809d2-7a37-4126-9d55-b649e737641b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_229148b7-6da5-4472-bb91-21766a7bfa43" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4fb809d2-7a37-4126-9d55-b649e737641b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandImprovementsMember_6c98c962-1548-4351-98ce-a59cb27a1a12" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LandImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4fb809d2-7a37-4126-9d55-b649e737641b" xlink:to="loc_us-gaap_LandImprovementsMember_6c98c962-1548-4351-98ce-a59cb27a1a12" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_BuildingsAndLeaseholdImprovementsMember_624deb8c-547d-46cc-b979-b247ba1dcc02" xlink:href="pnr-20231231.xsd#pnr_BuildingsAndLeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4fb809d2-7a37-4126-9d55-b649e737641b" xlink:to="loc_pnr_BuildingsAndLeaseholdImprovementsMember_624deb8c-547d-46cc-b979-b247ba1dcc02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_e10c431c-7f66-4bf0-8d43-e37fe6f4046c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4fb809d2-7a37-4126-9d55-b649e737641b" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_e10c431c-7f66-4bf0-8d43-e37fe6f4046c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_0a283863-7cd1-4ff2-bbe2-84e14f225408" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4fb809d2-7a37-4126-9d55-b649e737641b" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_0a283863-7cd1-4ff2-bbe2-84e14f225408" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_288c4809-7e1f-465f-a80b-e3ac3327a706" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_d0590794-40cd-42f7-8c51-da56b14abe7d" xlink:to="loc_srt_RangeAxis_288c4809-7e1f-465f-a80b-e3ac3327a706" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_288c4809-7e1f-465f-a80b-e3ac3327a706_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_288c4809-7e1f-465f-a80b-e3ac3327a706" xlink:to="loc_srt_RangeMember_288c4809-7e1f-465f-a80b-e3ac3327a706_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_9d25c959-80e8-4ae9-8f7a-14dd48321fd5" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_288c4809-7e1f-465f-a80b-e3ac3327a706" xlink:to="loc_srt_RangeMember_9d25c959-80e8-4ae9-8f7a-14dd48321fd5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_8eec541c-32e7-4207-a781-7e69432c73f9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_9d25c959-80e8-4ae9-8f7a-14dd48321fd5" xlink:to="loc_srt_MinimumMember_8eec541c-32e7-4207-a781-7e69432c73f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_9e4afb9a-c3c1-48be-9106-d9ff8ed713b0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_9d25c959-80e8-4ae9-8f7a-14dd48321fd5" xlink:to="loc_srt_MaximumMember_9e4afb9a-c3c1-48be-9106-d9ff8ed713b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_ed0cfa4e-c880-4671-abf1-c507d061c8e2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c19119e1-f552-4b16-b7d6-554ed7873edf" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_ed0cfa4e-c880-4671-abf1-c507d061c8e2" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentbyGeographicLocationDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentbyGeographicLocationDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentbyGeographicLocationDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_42e22f37-c121-46e1-8afa-06e26f957a8e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_3272390c-2d33-4f39-8218-7304a4ed3bd0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_42e22f37-c121-46e1-8afa-06e26f957a8e" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_3272390c-2d33-4f39-8218-7304a4ed3bd0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_c9286f1b-71d9-4690-a18b-5cc0d65f9d7e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_3272390c-2d33-4f39-8218-7304a4ed3bd0" xlink:to="loc_srt_StatementGeographicalAxis_c9286f1b-71d9-4690-a18b-5cc0d65f9d7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_c9286f1b-71d9-4690-a18b-5cc0d65f9d7e_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_c9286f1b-71d9-4690-a18b-5cc0d65f9d7e" xlink:to="loc_srt_SegmentGeographicalDomain_c9286f1b-71d9-4690-a18b-5cc0d65f9d7e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_843c5ae6-2bbf-4d04-98ea-555cb3a44d1c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_c9286f1b-71d9-4690-a18b-5cc0d65f9d7e" xlink:to="loc_srt_SegmentGeographicalDomain_843c5ae6-2bbf-4d04-98ea-555cb3a44d1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_4eef1553-2ebc-4da3-97bb-874f85c18672" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_843c5ae6-2bbf-4d04-98ea-555cb3a44d1c" xlink:to="loc_country_US_4eef1553-2ebc-4da3-97bb-874f85c18672" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_WesternEuropeMember_10402ae7-40c0-48f6-940d-8713c5dc69c0" xlink:href="pnr-20231231.xsd#pnr_WesternEuropeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_843c5ae6-2bbf-4d04-98ea-555cb3a44d1c" xlink:to="loc_pnr_WesternEuropeMember_10402ae7-40c0-48f6-940d-8713c5dc69c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DevelopingCountriesMember_07c8a89f-f15a-43ba-99fb-a5f99246af43" xlink:href="pnr-20231231.xsd#pnr_DevelopingCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_843c5ae6-2bbf-4d04-98ea-555cb3a44d1c" xlink:to="loc_pnr_DevelopingCountriesMember_07c8a89f-f15a-43ba-99fb-a5f99246af43" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_OtherDevelopedCountriesMember_393623a0-9bd0-4d12-8752-c081f5668c75" xlink:href="pnr-20231231.xsd#pnr_OtherDevelopedCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_843c5ae6-2bbf-4d04-98ea-555cb3a44d1c" xlink:to="loc_pnr_OtherDevelopedCountriesMember_393623a0-9bd0-4d12-8752-c081f5668c75" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_faa53069-a464-47ce-b146-55b0cb367977" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_42e22f37-c121-46e1-8afa-06e26f957a8e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_faa53069-a464-47ce-b146-55b0cb367977" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_7311437b-5fd4-41ea-9b1f-328a10864ed6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_42e22f37-c121-46e1-8afa-06e26f957a8e" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_7311437b-5fd4-41ea-9b1f-328a10864ed6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_9e7b6032-da01-4b26-b4c5-9344da97d039" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_42e22f37-c121-46e1-8afa-06e26f957a8e" xlink:to="loc_us-gaap_ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_9e7b6032-da01-4b26-b4c5-9344da97d039" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesInsuranceSubsidiaryDetails" xlink:type="simple" xlink:href="pnr-20231231.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesInsuranceSubsidiaryDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesInsuranceSubsidiaryDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_f9b3743f-795a-43f8-978f-7c83ed6c0a79" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable_dc8d7d30-d1d7-4f8a-8bac-f9e895afd747" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_f9b3743f-795a-43f8-978f-7c83ed6c0a79" xlink:to="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable_dc8d7d30-d1d7-4f8a-8bac-f9e895afd747" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_ee2af94b-b17e-4dd2-9750-b57b3c313b78" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable_dc8d7d30-d1d7-4f8a-8bac-f9e895afd747" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_ee2af94b-b17e-4dd2-9750-b57b3c313b78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_ee2af94b-b17e-4dd2-9750-b57b3c313b78_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_ee2af94b-b17e-4dd2-9750-b57b3c313b78" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_ee2af94b-b17e-4dd2-9750-b57b3c313b78_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_37f2fd27-9e19-43cf-94ea-885c2e359fb3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_ee2af94b-b17e-4dd2-9750-b57b3c313b78" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_37f2fd27-9e19-43cf-94ea-885c2e359fb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentLiabilitiesMember_305ff8a2-e317-4bae-94d1-31f2960231e9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_37f2fd27-9e19-43cf-94ea-885c2e359fb3" xlink:to="loc_us-gaap_OtherCurrentLiabilitiesMember_305ff8a2-e317-4bae-94d1-31f2960231e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_829c0a72-f6ef-4247-bdd0-0b7b5a1c856a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNoncurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_37f2fd27-9e19-43cf-94ea-885c2e359fb3" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_829c0a72-f6ef-4247-bdd0-0b7b5a1c856a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_75e221d2-514b-4d75-9a7c-3c1fb4188772" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_f9b3743f-795a-43f8-978f-7c83ed6c0a79" xlink:to="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_75e221d2-514b-4d75-9a7c-3c1fb4188772" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/AcquisitionsNarrativeDetails" xlink:type="simple" xlink:href="pnr-20231231.xsd#AcquisitionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/AcquisitionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_71fc703f-3fe6-4691-aaaa-ab255a497ac2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_71fc703f-3fe6-4691-aaaa-ab255a497ac2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_7f84bb81-d6b9-45a6-afe9-49e5be5fbc6c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_71fc703f-3fe6-4691-aaaa-ab255a497ac2" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_7f84bb81-d6b9-45a6-afe9-49e5be5fbc6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7f84bb81-d6b9-45a6-afe9-49e5be5fbc6c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_7f84bb81-d6b9-45a6-afe9-49e5be5fbc6c" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7f84bb81-d6b9-45a6-afe9-49e5be5fbc6c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6c7093bd-2e4f-4ec1-a0e9-332bd4b9c524" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_7f84bb81-d6b9-45a6-afe9-49e5be5fbc6c" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6c7093bd-2e4f-4ec1-a0e9-332bd4b9c524" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ManitowocIceMember_e968698f-ebf1-4839-8c18-557ba68270f8" xlink:href="pnr-20231231.xsd#pnr_ManitowocIceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6c7093bd-2e4f-4ec1-a0e9-332bd4b9c524" xlink:to="loc_pnr_ManitowocIceMember_e968698f-ebf1-4839-8c18-557ba68270f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_PleatcoHoldingsLLCMember_feac0272-903a-422d-a185-40808efce3d4" xlink:href="pnr-20231231.xsd#pnr_PleatcoHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6c7093bd-2e4f-4ec1-a0e9-332bd4b9c524" xlink:to="loc_pnr_PleatcoHoldingsLLCMember_feac0272-903a-422d-a185-40808efce3d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_KensBeverageIncMember_c48fb811-431a-4d72-aaa1-1117779eebe1" xlink:href="pnr-20231231.xsd#pnr_KensBeverageIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6c7093bd-2e4f-4ec1-a0e9-332bd4b9c524" xlink:to="loc_pnr_KensBeverageIncMember_c48fb811-431a-4d72-aaa1-1117779eebe1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_9d16aede-a286-46f0-ae72-c7cbc21632c7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_71fc703f-3fe6-4691-aaaa-ab255a497ac2" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_9d16aede-a286-46f0-ae72-c7cbc21632c7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_9d16aede-a286-46f0-ae72-c7cbc21632c7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_9d16aede-a286-46f0-ae72-c7cbc21632c7" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_9d16aede-a286-46f0-ae72-c7cbc21632c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_44847c48-c57b-4248-a718-61fb9c790939" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_9d16aede-a286-46f0-ae72-c7cbc21632c7" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_44847c48-c57b-4248-a718-61fb9c790939" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_7e235324-9d64-48a6-b508-e8d25eaed8be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_44847c48-c57b-4248-a718-61fb9c790939" xlink:to="loc_us-gaap_TradeNamesMember_7e235324-9d64-48a6-b508-e8d25eaed8be" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d2fe6b76-7b83-4b7a-8001-1c9a21f7de97" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_71fc703f-3fe6-4691-aaaa-ab255a497ac2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d2fe6b76-7b83-4b7a-8001-1c9a21f7de97" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d2fe6b76-7b83-4b7a-8001-1c9a21f7de97_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d2fe6b76-7b83-4b7a-8001-1c9a21f7de97" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d2fe6b76-7b83-4b7a-8001-1c9a21f7de97_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_896f3d9c-fda7-4ec9-b8ab-20a28b4b233a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d2fe6b76-7b83-4b7a-8001-1c9a21f7de97" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_896f3d9c-fda7-4ec9-b8ab-20a28b4b233a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_19a948a2-5cc8-457a-9c68-6985465376af" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_896f3d9c-fda7-4ec9-b8ab-20a28b4b233a" xlink:to="loc_us-gaap_CustomerRelationshipsMember_19a948a2-5cc8-457a-9c68-6985465376af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_d6da70a8-2292-4d99-8582-8566c78428f0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_896f3d9c-fda7-4ec9-b8ab-20a28b4b233a" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_d6da70a8-2292-4d99-8582-8566c78428f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_42ccd3b5-3da2-4d1c-8fe0-ed85917a4a03" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_896f3d9c-fda7-4ec9-b8ab-20a28b4b233a" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_42ccd3b5-3da2-4d1c-8fe0-ed85917a4a03" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_31dc3cd9-c484-4728-89e2-ab62159575cf" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_71fc703f-3fe6-4691-aaaa-ab255a497ac2" xlink:to="loc_srt_ConsolidationItemsAxis_31dc3cd9-c484-4728-89e2-ab62159575cf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_31dc3cd9-c484-4728-89e2-ab62159575cf_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_31dc3cd9-c484-4728-89e2-ab62159575cf" xlink:to="loc_srt_ConsolidationItemsDomain_31dc3cd9-c484-4728-89e2-ab62159575cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_613cc121-5928-40aa-a220-c87142df7c92" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_31dc3cd9-c484-4728-89e2-ab62159575cf" xlink:to="loc_srt_ConsolidationItemsDomain_613cc121-5928-40aa-a220-c87142df7c92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_75e72e1d-91ab-4026-b4e8-1752d8733a93" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_613cc121-5928-40aa-a220-c87142df7c92" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_75e72e1d-91ab-4026-b4e8-1752d8733a93" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentAxis_f0783421-7feb-4ccc-ba80-57003bdb7c2c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonrecurringAdjustmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_71fc703f-3fe6-4691-aaaa-ab255a497ac2" xlink:to="loc_us-gaap_NonrecurringAdjustmentAxis_f0783421-7feb-4ccc-ba80-57003bdb7c2c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentDomain_f0783421-7feb-4ccc-ba80-57003bdb7c2c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonrecurringAdjustmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_NonrecurringAdjustmentAxis_f0783421-7feb-4ccc-ba80-57003bdb7c2c" xlink:to="loc_us-gaap_NonrecurringAdjustmentDomain_f0783421-7feb-4ccc-ba80-57003bdb7c2c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentDomain_696df564-6d77-4bb5-9414-8a0262dcee05" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonrecurringAdjustmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_NonrecurringAdjustmentAxis_f0783421-7feb-4ccc-ba80-57003bdb7c2c" xlink:to="loc_us-gaap_NonrecurringAdjustmentDomain_696df564-6d77-4bb5-9414-8a0262dcee05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAdjustmentToInventoryMember_ca546a59-071d-4edf-8170-b43247c1208e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAdjustmentToInventoryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_696df564-6d77-4bb5-9414-8a0262dcee05" xlink:to="loc_us-gaap_FairValueAdjustmentToInventoryMember_ca546a59-071d-4edf-8170-b43247c1208e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquisitionRelatedCostsMember_92dfaf24-abd1-4bfc-898d-23c4bf9165a8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquisitionRelatedCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_696df564-6d77-4bb5-9414-8a0262dcee05" xlink:to="loc_us-gaap_AcquisitionRelatedCostsMember_92dfaf24-abd1-4bfc-898d-23c4bf9165a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_AcquisitionRelatedBridgeFinancingCostsMember_904676df-9791-4d45-88d1-411a7d5ce5b5" xlink:href="pnr-20231231.xsd#pnr_AcquisitionRelatedBridgeFinancingCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_696df564-6d77-4bb5-9414-8a0262dcee05" xlink:to="loc_pnr_AcquisitionRelatedBridgeFinancingCostsMember_904676df-9791-4d45-88d1-411a7d5ce5b5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_79020fe2-88bf-41bc-a0e0-cc183a5d13bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_71fc703f-3fe6-4691-aaaa-ab255a497ac2" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_79020fe2-88bf-41bc-a0e0-cc183a5d13bd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_79020fe2-88bf-41bc-a0e0-cc183a5d13bd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_79020fe2-88bf-41bc-a0e0-cc183a5d13bd" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_79020fe2-88bf-41bc-a0e0-cc183a5d13bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_c2a0af9b-12fc-4560-95b8-40661a965c06" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_79020fe2-88bf-41bc-a0e0-cc183a5d13bd" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_c2a0af9b-12fc-4560-95b8-40661a965c06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_7829a060-3ed1-4d72-bb28-4b6e4a0d4d98" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_c2a0af9b-12fc-4560-95b8-40661a965c06" xlink:to="loc_us-gaap_CostOfSalesMember_7829a060-3ed1-4d72-bb28-4b6e4a0d4d98" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_b399af95-21f1-423e-8ebe-cb730dddf63c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_c2a0af9b-12fc-4560-95b8-40661a965c06" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_b399af95-21f1-423e-8ebe-cb730dddf63c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseMember_25f13adf-7307-483e-a18f-1bf5a8f5e460" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_c2a0af9b-12fc-4560-95b8-40661a965c06" xlink:to="loc_us-gaap_InterestExpenseMember_25f13adf-7307-483e-a18f-1bf5a8f5e460" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_d9da67d4-f878-42e8-bf51-b64ad36ae14c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_d9da67d4-f878-42e8-bf51-b64ad36ae14c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_edd40631-0fba-4499-aa2e-c3dbdcabf27f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_us-gaap_Goodwill_edd40631-0fba-4499-aa2e-c3dbdcabf27f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefinitelivedIntangibleAssetsAcquired_815944e5-0246-4767-add5-e94d21188e27" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefinitelivedIntangibleAssetsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_us-gaap_IndefinitelivedIntangibleAssetsAcquired_815944e5-0246-4767-add5-e94d21188e27" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_9f5352c8-d4b1-4b13-ac4c-23e0e6b6b085" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_9f5352c8-d4b1-4b13-ac4c-23e0e6b6b085" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_509bb871-199b-4f10-8ad4-3e6bb867049d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_509bb871-199b-4f10-8ad4-3e6bb867049d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsExpensesAndLossesRecognized_e3edee45-c4d3-44e0-ac7d-30207e222e35" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsExpensesAndLossesRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsExpensesAndLossesRecognized_e3edee45-c4d3-44e0-ac7d-30207e222e35" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_c7cf8e63-b74c-49fc-b753-e5eab5b6a709" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_c7cf8e63-b74c-49fc-b753-e5eab5b6a709" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_d37811f3-afb4-4756-a34f-72983effbdb2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_d37811f3-afb4-4756-a34f-72983effbdb2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_BusinessCombinationProFormaInformationAmortizationOfIntangibleAssetsOfAcquireeSinceAcquisitionDateActual_72dc903d-5cf7-4a1a-b388-50e71ea8fbcb" xlink:href="pnr-20231231.xsd#pnr_BusinessCombinationProFormaInformationAmortizationOfIntangibleAssetsOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_pnr_BusinessCombinationProFormaInformationAmortizationOfIntangibleAssetsOfAcquireeSinceAcquisitionDateActual_72dc903d-5cf7-4a1a-b388-50e71ea8fbcb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_BusinessCombinationProFormaInformationAmortizationOfInventoryFairMarketValueAdjustmentOfAcquireeSinceAcquisitionDateActual_bcfa0973-abd3-44cb-b668-d9dd90faea49" xlink:href="pnr-20231231.xsd#pnr_BusinessCombinationProFormaInformationAmortizationOfInventoryFairMarketValueAdjustmentOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_pnr_BusinessCombinationProFormaInformationAmortizationOfInventoryFairMarketValueAdjustmentOfAcquireeSinceAcquisitionDateActual_bcfa0973-abd3-44cb-b668-d9dd90faea49" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_BusinessAcquisitionProFormaIntangibleAssetAmortization_c030e62c-d004-469e-aa20-b967cde9a527" xlink:href="pnr-20231231.xsd#pnr_BusinessAcquisitionProFormaIntangibleAssetAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_pnr_BusinessAcquisitionProFormaIntangibleAssetAmortization_c030e62c-d004-469e-aa20-b967cde9a527" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_98172e23-1a29-4648-bdfb-44cd17ada0ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_98172e23-1a29-4648-bdfb-44cd17ada0ba" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_48ca3ec4-7512-4bb8-8da2-705092b3692e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_48ca3ec4-7512-4bb8-8da2-705092b3692e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_5a800f3a-e485-4149-8bac-cd5ee1baa0f1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_20bef7ca-b3ef-413b-a1d9-c22efed4540c" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_5a800f3a-e485-4149-8bac-cd5ee1baa0f1" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/AcquisitionsScheduleofRecognizedIdentifiedAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="simple" xlink:href="pnr-20231231.xsd#AcquisitionsScheduleofRecognizedIdentifiedAssetsAcquiredandLiabilitiesAssumedDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/AcquisitionsScheduleofRecognizedIdentifiedAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_a6051959-fbba-49e5-8114-554de2cdf714" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_a6051959-fbba-49e5-8114-554de2cdf714" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_3b561b70-0fad-4fe4-ad43-81e1f71cbfd2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_a6051959-fbba-49e5-8114-554de2cdf714" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_3b561b70-0fad-4fe4-ad43-81e1f71cbfd2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3b561b70-0fad-4fe4-ad43-81e1f71cbfd2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_3b561b70-0fad-4fe4-ad43-81e1f71cbfd2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3b561b70-0fad-4fe4-ad43-81e1f71cbfd2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_dd902dd0-9220-41de-9b53-f484f1957757" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_3b561b70-0fad-4fe4-ad43-81e1f71cbfd2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_dd902dd0-9220-41de-9b53-f484f1957757" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ManitowocIceMember_118b2328-5415-472a-8bb0-2db1db9340b9" xlink:href="pnr-20231231.xsd#pnr_ManitowocIceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_dd902dd0-9220-41de-9b53-f484f1957757" xlink:to="loc_pnr_ManitowocIceMember_118b2328-5415-472a-8bb0-2db1db9340b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_e64f96ba-55bf-4a04-b99f-21f26ede97a4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_e64f96ba-55bf-4a04-b99f-21f26ede97a4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_380949e3-3dbc-4806-92ad-e4e936391dfc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_380949e3-3dbc-4806-92ad-e4e936391dfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_ac0fa59e-08b4-4638-a6d0-787066fae221" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_ac0fa59e-08b4-4638-a6d0-787066fae221" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_223c9cfc-e6ad-44ae-b17c-a6cbcc0913ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_223c9cfc-e6ad-44ae-b17c-a6cbcc0913ac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_756d7fd2-6202-4b5d-8caf-f286619b67fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_756d7fd2-6202-4b5d-8caf-f286619b67fc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_bb679006-9010-464a-96f7-b76ecf2f6ba5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_bb679006-9010-464a-96f7-b76ecf2f6ba5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_965f4a2c-f453-4c7f-9a7c-bc4b7d250ec5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:to="loc_us-gaap_Goodwill_965f4a2c-f453-4c7f-9a7c-bc4b7d250ec5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_d7125760-5773-4d70-b438-5346fc11964c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_d7125760-5773-4d70-b438-5346fc11964c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities_700dcd56-575f-4609-9d44-673b97008fc5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities_700dcd56-575f-4609-9d44-673b97008fc5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_fd428f4c-022d-4b8c-b2d9-f699329af687" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_fd428f4c-022d-4b8c-b2d9-f699329af687" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_c048fec6-35c4-46bd-99ea-51e33938c1c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9ffeb6a9-f727-4be4-8a43-62541790653b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_c048fec6-35c4-46bd-99ea-51e33938c1c4" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/AcquisitionsScheduleofProFormaInformationDetails" xlink:type="simple" xlink:href="pnr-20231231.xsd#AcquisitionsScheduleofProFormaInformationDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/AcquisitionsScheduleofProFormaInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_297b0aac-2026-4fe9-911b-f3026b8e9a02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_67696bcb-a539-498a-8213-1aa24400a439" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_297b0aac-2026-4fe9-911b-f3026b8e9a02" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_67696bcb-a539-498a-8213-1aa24400a439" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_0ac6a2ce-0b82-4544-a483-471fa34f9eb9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_67696bcb-a539-498a-8213-1aa24400a439" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_0ac6a2ce-0b82-4544-a483-471fa34f9eb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0ac6a2ce-0b82-4544-a483-471fa34f9eb9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_0ac6a2ce-0b82-4544-a483-471fa34f9eb9" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0ac6a2ce-0b82-4544-a483-471fa34f9eb9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ca49a032-4d31-4a9b-8a91-0ef3456baab9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_0ac6a2ce-0b82-4544-a483-471fa34f9eb9" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ca49a032-4d31-4a9b-8a91-0ef3456baab9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ManitowocIceMember_1c51cdbb-4256-49c9-bdec-d2274d0b4a15" xlink:href="pnr-20231231.xsd#pnr_ManitowocIceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ca49a032-4d31-4a9b-8a91-0ef3456baab9" xlink:to="loc_pnr_ManitowocIceMember_1c51cdbb-4256-49c9-bdec-d2274d0b4a15" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_13d90ff2-e349-48c9-9ec0-5e0b832a40de" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_297b0aac-2026-4fe9-911b-f3026b8e9a02" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_13d90ff2-e349-48c9-9ec0-5e0b832a40de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTax_199ae27a-abbb-4216-830b-c5573e4fcf6a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionsProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_297b0aac-2026-4fe9-911b-f3026b8e9a02" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTax_199ae27a-abbb-4216-830b-c5573e4fcf6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsNetOfTaxPerShareAbstract_92310e13-6a42-45dd-a452-4848174ad292" xlink:href="pnr-20231231.xsd#pnr_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsNetOfTaxPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_297b0aac-2026-4fe9-911b-f3026b8e9a02" xlink:to="loc_pnr_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsNetOfTaxPerShareAbstract_92310e13-6a42-45dd-a452-4848174ad292" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic_aa5a1bb8-d2ac-4f9e-8a2a-26843a52489b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsNetOfTaxPerShareAbstract_92310e13-6a42-45dd-a452-4848174ad292" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic_aa5a1bb8-d2ac-4f9e-8a2a-26843a52489b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted_86bd1b5d-ab63-4365-a618-eff374f40e6e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsNetOfTaxPerShareAbstract_92310e13-6a42-45dd-a452-4848174ad292" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted_86bd1b5d-ab63-4365-a618-eff374f40e6e" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/EarningsPerShareDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#EarningsPerShareDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/EarningsPerShareDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ComputationOfEarningsPerShareLineItems_dd51ca4e-10ab-456d-8e46-090f3ae7e24a" xlink:href="pnr-20231231.xsd#pnr_ComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_EarningsPerShareTable_33d25256-e28f-477d-9734-28bb0be6ed28" xlink:href="pnr-20231231.xsd#pnr_EarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnr_ComputationOfEarningsPerShareLineItems_dd51ca4e-10ab-456d-8e46-090f3ae7e24a" xlink:to="loc_pnr_EarningsPerShareTable_33d25256-e28f-477d-9734-28bb0be6ed28" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_570fb572-fe09-431b-98da-480a72ed99b7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_EarningsPerShareTable_33d25256-e28f-477d-9734-28bb0be6ed28" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_570fb572-fe09-431b-98da-480a72ed99b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_570fb572-fe09-431b-98da-480a72ed99b7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_570fb572-fe09-431b-98da-480a72ed99b7" xlink:to="loc_us-gaap_EquityComponentDomain_570fb572-fe09-431b-98da-480a72ed99b7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_9ccf2bb0-2ef3-423d-8fa6-49c25756b950" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_570fb572-fe09-431b-98da-480a72ed99b7" xlink:to="loc_us-gaap_EquityComponentDomain_9ccf2bb0-2ef3-423d-8fa6-49c25756b950" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_02c48f93-1ec7-42b2-b229-252e42c713b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_9ccf2bb0-2ef3-423d-8fa6-49c25756b950" xlink:to="loc_us-gaap_RetainedEarningsMember_02c48f93-1ec7-42b2-b229-252e42c713b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_3d0e2841-e942-4f58-9133-088b1a51a237" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ComputationOfEarningsPerShareLineItems_dd51ca4e-10ab-456d-8e46-090f3ae7e24a" xlink:to="loc_us-gaap_NetIncomeLoss_3d0e2841-e942-4f58-9133-088b1a51a237" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperations_5d7bd684-5260-440a-ae67-95d7f02b26a6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ComputationOfEarningsPerShareLineItems_dd51ca4e-10ab-456d-8e46-090f3ae7e24a" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperations_5d7bd684-5260-440a-ae67-95d7f02b26a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_df1b2a2a-2e40-4960-a174-587b9bdc1f90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ComputationOfEarningsPerShareLineItems_dd51ca4e-10ab-456d-8e46-090f3ae7e24a" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_df1b2a2a-2e40-4960-a174-587b9bdc1f90" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_2b83d261-2495-42cc-a498-6fe3765d48d5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_df1b2a2a-2e40-4960-a174-587b9bdc1f90" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_2b83d261-2495-42cc-a498-6fe3765d48d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_74a2d668-d7ae-43e6-9cab-4fc669e79491" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_df1b2a2a-2e40-4960-a174-587b9bdc1f90" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_74a2d668-d7ae-43e6-9cab-4fc669e79491" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_b327beb1-ff98-4d28-bd3a-ac9c814ed4ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_df1b2a2a-2e40-4960-a174-587b9bdc1f90" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_b327beb1-ff98-4d28-bd3a-ac9c814ed4ef" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_EarningsPerShareNumeratorAbstract_a3ff9761-45fd-4db8-ae8d-e45f20609945" xlink:href="pnr-20231231.xsd#pnr_EarningsPerShareNumeratorAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ComputationOfEarningsPerShareLineItems_dd51ca4e-10ab-456d-8e46-090f3ae7e24a" xlink:to="loc_pnr_EarningsPerShareNumeratorAbstract_a3ff9761-45fd-4db8-ae8d-e45f20609945" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare_9522063b-d3db-41fc-9ea6-c3bf93d93fb8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsPerBasicShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_EarningsPerShareNumeratorAbstract_a3ff9761-45fd-4db8-ae8d-e45f20609945" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare_9522063b-d3db-41fc-9ea6-c3bf93d93fb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare_835c44b1-0ab8-4367-aca1-edcf99815eed" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_EarningsPerShareNumeratorAbstract_a3ff9761-45fd-4db8-ae8d-e45f20609945" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare_835c44b1-0ab8-4367-aca1-edcf99815eed" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_fdc07f87-9910-4f3b-a008-61ba7b736f83" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_EarningsPerShareNumeratorAbstract_a3ff9761-45fd-4db8-ae8d-e45f20609945" xlink:to="loc_us-gaap_EarningsPerShareBasic_fdc07f87-9910-4f3b-a008-61ba7b736f83" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_4b15bece-3766-4edc-bd54-2f51bc3cc7f5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_EarningsPerShareNumeratorAbstract_a3ff9761-45fd-4db8-ae8d-e45f20609945" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_4b15bece-3766-4edc-bd54-2f51bc3cc7f5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare_99964760-8eef-4851-92b5-1a42dfa1b7a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_EarningsPerShareNumeratorAbstract_a3ff9761-45fd-4db8-ae8d-e45f20609945" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare_99964760-8eef-4851-92b5-1a42dfa1b7a1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_b3124839-23d4-4254-bfde-e4d5cc3c5be1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_EarningsPerShareNumeratorAbstract_a3ff9761-45fd-4db8-ae8d-e45f20609945" xlink:to="loc_us-gaap_EarningsPerShareDiluted_b3124839-23d4-4254-bfde-e4d5cc3c5be1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_cc307a43-232c-4a2b-9de3-6d1fc14dbd8d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ComputationOfEarningsPerShareLineItems_dd51ca4e-10ab-456d-8e46-090f3ae7e24a" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_cc307a43-232c-4a2b-9de3-6d1fc14dbd8d" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/RestructuringCostsIncludedinSellingGeneralAdministrativeexpensesonConsolidatedStatementsofIncomeDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#RestructuringCostsIncludedinSellingGeneralAdministrativeexpensesonConsolidatedStatementsofIncomeDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/RestructuringCostsIncludedinSellingGeneralAdministrativeexpensesonConsolidatedStatementsofIncomeDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_c4944931-1e90-4aa9-9a66-89d6abc162f5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_e20c782b-f381-4fc9-a59c-f0aad187a899" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_c4944931-1e90-4aa9-9a66-89d6abc162f5" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_e20c782b-f381-4fc9-a59c-f0aad187a899" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_82445be7-b0ef-4bd1-a70c-042eee7c881e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_e20c782b-f381-4fc9-a59c-f0aad187a899" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_82445be7-b0ef-4bd1-a70c-042eee7c881e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_82445be7-b0ef-4bd1-a70c-042eee7c881e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_82445be7-b0ef-4bd1-a70c-042eee7c881e" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_82445be7-b0ef-4bd1-a70c-042eee7c881e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_c817232a-96b4-4bc2-9bc9-4dd9f617094a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_82445be7-b0ef-4bd1-a70c-042eee7c881e" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_c817232a-96b4-4bc2-9bc9-4dd9f617094a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SeveranceAndRelatedCostsMember_159d3846-cd03-4679-b1f6-6c008e345fe0" xlink:href="pnr-20231231.xsd#pnr_SeveranceAndRelatedCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_c817232a-96b4-4bc2-9bc9-4dd9f617094a" xlink:to="loc_pnr_SeveranceAndRelatedCostsMember_159d3846-cd03-4679-b1f6-6c008e345fe0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRestructuringMember_d76c5a52-0c06-4025-b199-c01ce105a6cd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherRestructuringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_c817232a-96b4-4bc2-9bc9-4dd9f617094a" xlink:to="loc_us-gaap_OtherRestructuringMember_d76c5a52-0c06-4025-b199-c01ce105a6cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_AssetImpairmentAndWriteOffsMember_79f14c37-0ad8-4b9f-bca7-76c49ae55166" xlink:href="pnr-20231231.xsd#pnr_AssetImpairmentAndWriteOffsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_c817232a-96b4-4bc2-9bc9-4dd9f617094a" xlink:to="loc_pnr_AssetImpairmentAndWriteOffsMember_79f14c37-0ad8-4b9f-bca7-76c49ae55166" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TransformationTypeAxis_a52270b4-628f-4411-a505-5464351123aa" xlink:href="pnr-20231231.xsd#pnr_TransformationTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_e20c782b-f381-4fc9-a59c-f0aad187a899" xlink:to="loc_pnr_TransformationTypeAxis_a52270b4-628f-4411-a505-5464351123aa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TransformationTypeDomain_a52270b4-628f-4411-a505-5464351123aa_default" xlink:href="pnr-20231231.xsd#pnr_TransformationTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_pnr_TransformationTypeAxis_a52270b4-628f-4411-a505-5464351123aa" xlink:to="loc_pnr_TransformationTypeDomain_a52270b4-628f-4411-a505-5464351123aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TransformationTypeDomain_9c2e7089-dfb6-4cbd-a9a8-02205c7214b4" xlink:href="pnr-20231231.xsd#pnr_TransformationTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_pnr_TransformationTypeAxis_a52270b4-628f-4411-a505-5464351123aa" xlink:to="loc_pnr_TransformationTypeDomain_9c2e7089-dfb6-4cbd-a9a8-02205c7214b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SeveranceAndRelatedCostsMember_1f50e670-7b10-49d5-ac88-5e8669092580" xlink:href="pnr-20231231.xsd#pnr_SeveranceAndRelatedCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_TransformationTypeDomain_9c2e7089-dfb6-4cbd-a9a8-02205c7214b4" xlink:to="loc_pnr_SeveranceAndRelatedCostsMember_1f50e670-7b10-49d5-ac88-5e8669092580" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_OtherTransformationMember_dbf92a33-893b-4e77-9fa0-ddf5f0577c9b" xlink:href="pnr-20231231.xsd#pnr_OtherTransformationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_TransformationTypeDomain_9c2e7089-dfb6-4cbd-a9a8-02205c7214b4" xlink:to="loc_pnr_OtherTransformationMember_dbf92a33-893b-4e77-9fa0-ddf5f0577c9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_7468c2da-07dd-4b2c-97f5-adbaf6eda160" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_c4944931-1e90-4aa9-9a66-89d6abc162f5" xlink:to="loc_us-gaap_RestructuringCharges_7468c2da-07dd-4b2c-97f5-adbaf6eda160" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TransformationCosts_5360b7b0-3b1a-4bb7-897e-2baa500e1b22" xlink:href="pnr-20231231.xsd#pnr_TransformationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_c4944931-1e90-4aa9-9a66-89d6abc162f5" xlink:to="loc_pnr_TransformationCosts_5360b7b0-3b1a-4bb7-897e-2baa500e1b22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TotalRestructuringAndTransformationCosts_f8bbf245-8323-4472-966d-3fae00f49918" xlink:href="pnr-20231231.xsd#pnr_TotalRestructuringAndTransformationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_c4944931-1e90-4aa9-9a66-89d6abc162f5" xlink:to="loc_pnr_TotalRestructuringAndTransformationCosts_f8bbf245-8323-4472-966d-3fae00f49918" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/RestructuringRestructuringCostsbySegmentDetails" xlink:type="simple" xlink:href="pnr-20231231.xsd#RestructuringRestructuringCostsbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/RestructuringRestructuringCostsbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_fac8f962-39eb-4dd4-92ff-e58d174e43d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_4dc63db4-bde4-4e12-9b62-fc7c1afc71a5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_fac8f962-39eb-4dd4-92ff-e58d174e43d8" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_4dc63db4-bde4-4e12-9b62-fc7c1afc71a5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_7c61c4e3-4992-4c80-8928-8ce86e9aa7c2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_4dc63db4-bde4-4e12-9b62-fc7c1afc71a5" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_7c61c4e3-4992-4c80-8928-8ce86e9aa7c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_7c61c4e3-4992-4c80-8928-8ce86e9aa7c2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7c61c4e3-4992-4c80-8928-8ce86e9aa7c2" xlink:to="loc_us-gaap_SegmentDomain_7c61c4e3-4992-4c80-8928-8ce86e9aa7c2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_84a4abe7-3969-483d-8afd-ef510df45eba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7c61c4e3-4992-4c80-8928-8ce86e9aa7c2" xlink:to="loc_us-gaap_SegmentDomain_84a4abe7-3969-483d-8afd-ef510df45eba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateAndOtherMember_a30c4d01-17e5-4aa1-b36f-a5bb5aad8271" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_84a4abe7-3969-483d-8afd-ef510df45eba" xlink:to="loc_us-gaap_CorporateAndOtherMember_a30c4d01-17e5-4aa1-b36f-a5bb5aad8271" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_FlowMember_de10e9ed-8775-4866-a209-dbace66e3e02" xlink:href="pnr-20231231.xsd#pnr_FlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_84a4abe7-3969-483d-8afd-ef510df45eba" xlink:to="loc_pnr_FlowMember_de10e9ed-8775-4866-a209-dbace66e3e02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_WaterSolutionsMember_6b7121c8-1a93-4485-b318-4d785e99b967" xlink:href="pnr-20231231.xsd#pnr_WaterSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_84a4abe7-3969-483d-8afd-ef510df45eba" xlink:to="loc_pnr_WaterSolutionsMember_6b7121c8-1a93-4485-b318-4d785e99b967" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_PoolMember_93393947-6c25-490c-a143-9ba1f59deba7" xlink:href="pnr-20231231.xsd#pnr_PoolMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_84a4abe7-3969-483d-8afd-ef510df45eba" xlink:to="loc_pnr_PoolMember_93393947-6c25-490c-a143-9ba1f59deba7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TotalRestructuringAndTransformationCosts_fa3cd36f-9aee-4825-bf65-4d2a4b2a42d9" xlink:href="pnr-20231231.xsd#pnr_TotalRestructuringAndTransformationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_fac8f962-39eb-4dd4-92ff-e58d174e43d8" xlink:to="loc_pnr_TotalRestructuringAndTransformationCosts_fa3cd36f-9aee-4825-bf65-4d2a4b2a42d9" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/RestructuringAccrualActivityrecordedonCondensedConsolidatedBalanceSheetsDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#RestructuringAccrualActivityrecordedonCondensedConsolidatedBalanceSheetsDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/RestructuringAccrualActivityrecordedonCondensedConsolidatedBalanceSheetsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_572afcee-6fe9-4df8-b26b-3b11b2fa5443" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_896ad2fa-5fef-4175-aa44-139b8d814f36" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_572afcee-6fe9-4df8-b26b-3b11b2fa5443" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_896ad2fa-5fef-4175-aa44-139b8d814f36" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_3406691f-fef6-41ef-820b-a05c683dcb46" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_896ad2fa-5fef-4175-aa44-139b8d814f36" xlink:to="loc_dei_LegalEntityAxis_3406691f-fef6-41ef-820b-a05c683dcb46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_3406691f-fef6-41ef-820b-a05c683dcb46_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_3406691f-fef6-41ef-820b-a05c683dcb46" xlink:to="loc_dei_EntityDomain_3406691f-fef6-41ef-820b-a05c683dcb46_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_6059fe96-dc3e-4b48-897e-e6bf7f36ed5c" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_3406691f-fef6-41ef-820b-a05c683dcb46" xlink:to="loc_dei_EntityDomain_6059fe96-dc3e-4b48-897e-e6bf7f36ed5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveRollForward_64d308ef-0e48-45c3-ad96-c1107479a5fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringReserveRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_572afcee-6fe9-4df8-b26b-3b11b2fa5443" xlink:to="loc_us-gaap_RestructuringReserveRollForward_64d308ef-0e48-45c3-ad96-c1107479a5fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_4df7d7b8-d1a8-41fd-a626-517809539509" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_64d308ef-0e48-45c3-ad96-c1107479a5fc" xlink:to="loc_us-gaap_RestructuringReserve_4df7d7b8-d1a8-41fd-a626-517809539509" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostIncurredCost_fb3fb647-0d37-4eb4-bc83-41d830ccc3fe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringAndRelatedCostIncurredCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_64d308ef-0e48-45c3-ad96-c1107479a5fc" xlink:to="loc_us-gaap_RestructuringAndRelatedCostIncurredCost_fb3fb647-0d37-4eb4-bc83-41d830ccc3fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRestructuring_1035148a-bb0b-46c9-99a4-4886da0be0f1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForRestructuring"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_64d308ef-0e48-45c3-ad96-c1107479a5fc" xlink:to="loc_us-gaap_PaymentsForRestructuring_1035148a-bb0b-46c9-99a4-4886da0be0f1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_585ec49d-d201-42ce-bea7-c253ebbda0cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringReserve"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringIncurredCostStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_3f0f52df-9054-4743-b066-019c81f2a0c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringIncurredCostStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_572afcee-6fe9-4df8-b26b-3b11b2fa5443" xlink:to="loc_us-gaap_RestructuringIncurredCostStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_3f0f52df-9054-4743-b066-019c81f2a0c9" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/GoodwillandOtherIdentifiableIntangibleAssetsChangesinCarryingAmountofGoodwillbySegmentDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#GoodwillandOtherIdentifiableIntangibleAssetsChangesinCarryingAmountofGoodwillbySegmentDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/GoodwillandOtherIdentifiableIntangibleAssetsChangesinCarryingAmountofGoodwillbySegmentDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_4c6cc867-61ef-4bfd-a665-87ff9dce38e0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_39adc752-e4b6-4181-8b50-d010acc96bd8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_4c6cc867-61ef-4bfd-a665-87ff9dce38e0" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_39adc752-e4b6-4181-8b50-d010acc96bd8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_b1d13afb-1187-4922-9818-a36fceaaeda2" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_39adc752-e4b6-4181-8b50-d010acc96bd8" xlink:to="loc_dei_LegalEntityAxis_b1d13afb-1187-4922-9818-a36fceaaeda2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_b1d13afb-1187-4922-9818-a36fceaaeda2_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_b1d13afb-1187-4922-9818-a36fceaaeda2" xlink:to="loc_dei_EntityDomain_b1d13afb-1187-4922-9818-a36fceaaeda2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_a2b501f1-c6b5-46fd-8f85-2bea29feb5c0" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_b1d13afb-1187-4922-9818-a36fceaaeda2" xlink:to="loc_dei_EntityDomain_a2b501f1-c6b5-46fd-8f85-2bea29feb5c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_620d9873-2c50-4762-ad49-a6d31b197919" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_39adc752-e4b6-4181-8b50-d010acc96bd8" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_620d9873-2c50-4762-ad49-a6d31b197919" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_620d9873-2c50-4762-ad49-a6d31b197919_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_620d9873-2c50-4762-ad49-a6d31b197919" xlink:to="loc_us-gaap_SegmentDomain_620d9873-2c50-4762-ad49-a6d31b197919_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_109ffc24-be1e-4eda-b680-3f2e474c4ff9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_620d9873-2c50-4762-ad49-a6d31b197919" xlink:to="loc_us-gaap_SegmentDomain_109ffc24-be1e-4eda-b680-3f2e474c4ff9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_FlowMember_fbf74ad8-961d-466f-a7db-7e3a9a0c03c7" xlink:href="pnr-20231231.xsd#pnr_FlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_109ffc24-be1e-4eda-b680-3f2e474c4ff9" xlink:to="loc_pnr_FlowMember_fbf74ad8-961d-466f-a7db-7e3a9a0c03c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_WaterSolutionsMember_7a32b899-05ac-45de-9610-b201f4c9b9d9" xlink:href="pnr-20231231.xsd#pnr_WaterSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_109ffc24-be1e-4eda-b680-3f2e474c4ff9" xlink:to="loc_pnr_WaterSolutionsMember_7a32b899-05ac-45de-9610-b201f4c9b9d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_PoolMember_0168cc66-e9ed-46de-8c18-3b06efccdb4a" xlink:href="pnr-20231231.xsd#pnr_PoolMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_109ffc24-be1e-4eda-b680-3f2e474c4ff9" xlink:to="loc_pnr_PoolMember_0168cc66-e9ed-46de-8c18-3b06efccdb4a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_21636b36-51c5-4660-9db0-875f13f68576" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_4c6cc867-61ef-4bfd-a665-87ff9dce38e0" xlink:to="loc_us-gaap_GoodwillRollForward_21636b36-51c5-4660-9db0-875f13f68576" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_36b17dfd-f397-4973-84d0-b737f4537072" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_21636b36-51c5-4660-9db0-875f13f68576" xlink:to="loc_us-gaap_Goodwill_36b17dfd-f397-4973-84d0-b737f4537072" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_abdea7bd-39a4-4078-be7f-de5656da384a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillAcquiredDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_21636b36-51c5-4660-9db0-875f13f68576" xlink:to="loc_us-gaap_GoodwillAcquiredDuringPeriod_abdea7bd-39a4-4078-be7f-de5656da384a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillOtherIncreaseDecrease_68bce2ba-90a0-419d-a78b-4af1262ee315" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillOtherIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_21636b36-51c5-4660-9db0-875f13f68576" xlink:to="loc_us-gaap_GoodwillOtherIncreaseDecrease_68bce2ba-90a0-419d-a78b-4af1262ee315" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_a0102349-4fd0-4a5b-8df7-b7a313435768" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_2bf2cf8d-2040-4934-bb76-96ce5e42045c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillPurchaseAccountingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_4c6cc867-61ef-4bfd-a665-87ff9dce38e0" xlink:to="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_2bf2cf8d-2040-4934-bb76-96ce5e42045c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/GoodwillandOtherIdentifiableIntangibleAssetsIdentifiableIntangibleAssetsDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#GoodwillandOtherIdentifiableIntangibleAssetsIdentifiableIntangibleAssetsDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/GoodwillandOtherIdentifiableIntangibleAssetsIdentifiableIntangibleAssetsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_04a8768c-a21a-40a6-978e-aef1ec6729d5" xlink:href="pnr-20231231.xsd#pnr_AcquiredIntangibleAssetsByMajorClassLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ScheduleOfAcquiredIntangibleAssetsByMajorClassTable_144e0958-a18d-4921-8a3f-3d2803032273" xlink:href="pnr-20231231.xsd#pnr_ScheduleOfAcquiredIntangibleAssetsByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_04a8768c-a21a-40a6-978e-aef1ec6729d5" xlink:to="loc_pnr_ScheduleOfAcquiredIntangibleAssetsByMajorClassTable_144e0958-a18d-4921-8a3f-3d2803032273" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_de2d1b11-afc4-4047-9a86-ea4b65da15c8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_ScheduleOfAcquiredIntangibleAssetsByMajorClassTable_144e0958-a18d-4921-8a3f-3d2803032273" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_de2d1b11-afc4-4047-9a86-ea4b65da15c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_de2d1b11-afc4-4047-9a86-ea4b65da15c8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_de2d1b11-afc4-4047-9a86-ea4b65da15c8" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_de2d1b11-afc4-4047-9a86-ea4b65da15c8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_802c1223-9cc2-4353-8ecd-40a0c8a49788" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_de2d1b11-afc4-4047-9a86-ea4b65da15c8" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_802c1223-9cc2-4353-8ecd-40a0c8a49788" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_377fd3df-acf0-49fd-ba0e-2bb055e25ebb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_802c1223-9cc2-4353-8ecd-40a0c8a49788" xlink:to="loc_us-gaap_CustomerRelationshipsMember_377fd3df-acf0-49fd-ba0e-2bb055e25ebb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PatentedTechnologyMember_52a67dff-282f-465e-9ee9-d465c009a07e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PatentedTechnologyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_802c1223-9cc2-4353-8ecd-40a0c8a49788" xlink:to="loc_us-gaap_PatentedTechnologyMember_52a67dff-282f-465e-9ee9-d465c009a07e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_cc780177-6c26-4847-a1ac-0a032d15c650" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_802c1223-9cc2-4353-8ecd-40a0c8a49788" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_cc780177-6c26-4847-a1ac-0a032d15c650" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_6961d2d4-5395-4d9c-97ed-3babc3b12473" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_04a8768c-a21a-40a6-978e-aef1ec6729d5" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_6961d2d4-5395-4d9c-97ed-3babc3b12473" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_7b8d1170-d675-4518-8672-9e5757ef5e40" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_04a8768c-a21a-40a6-978e-aef1ec6729d5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_7b8d1170-d675-4518-8672-9e5757ef5e40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_537f6ef1-ea2c-4ee8-9d69-7862d3ccc43d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_04a8768c-a21a-40a6-978e-aef1ec6729d5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_537f6ef1-ea2c-4ee8-9d69-7862d3ccc43d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ff2d9864-6842-410b-bf52-bbe943df4648" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_04a8768c-a21a-40a6-978e-aef1ec6729d5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ff2d9864-6842-410b-bf52-bbe943df4648" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_33139920-0e14-45a0-8c20-f7e9c5db4d5f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_04a8768c-a21a-40a6-978e-aef1ec6729d5" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_33139920-0e14-45a0-8c20-f7e9c5db4d5f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_a14db903-922d-4e28-a4a3-a6ae642bfbd7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_04a8768c-a21a-40a6-978e-aef1ec6729d5" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_a14db903-922d-4e28-a4a3-a6ae642bfbd7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_c4a8b02e-120e-424b-842f-a398fdf69765" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_04a8768c-a21a-40a6-978e-aef1ec6729d5" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_c4a8b02e-120e-424b-842f-a398fdf69765" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_3ebd792f-d55a-4a1e-91ab-1a98ebd3c7f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_04a8768c-a21a-40a6-978e-aef1ec6729d5" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_3ebd792f-d55a-4a1e-91ab-1a98ebd3c7f2" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/GoodwillandOtherIdentifiableIntangibleAssetsEstimatedFutureAmortizationExpenseforIdentifiableIntangibleAssetsDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#GoodwillandOtherIdentifiableIntangibleAssetsEstimatedFutureAmortizationExpenseforIdentifiableIntangibleAssetsDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/GoodwillandOtherIdentifiableIntangibleAssetsEstimatedFutureAmortizationExpenseforIdentifiableIntangibleAssetsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ExpectedAmortizationExpenseLineItems_4543e043-7340-4fd5-9c15-86abd3f0383b" xlink:href="pnr-20231231.xsd#pnr_ExpectedAmortizationExpenseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ExpectedAmortizationExpenseTable_cd8c593c-7663-4f4a-a401-0b3b670b8703" xlink:href="pnr-20231231.xsd#pnr_ExpectedAmortizationExpenseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnr_ExpectedAmortizationExpenseLineItems_4543e043-7340-4fd5-9c15-86abd3f0383b" xlink:to="loc_pnr_ExpectedAmortizationExpenseTable_cd8c593c-7663-4f4a-a401-0b3b670b8703" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_041157e5-bcff-4882-adef-6179244dfec5" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_ExpectedAmortizationExpenseTable_cd8c593c-7663-4f4a-a401-0b3b670b8703" xlink:to="loc_dei_LegalEntityAxis_041157e5-bcff-4882-adef-6179244dfec5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_041157e5-bcff-4882-adef-6179244dfec5_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_041157e5-bcff-4882-adef-6179244dfec5" xlink:to="loc_dei_EntityDomain_041157e5-bcff-4882-adef-6179244dfec5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_0c66e707-db4a-48df-86e8-0147e7ee9ccb" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_041157e5-bcff-4882-adef-6179244dfec5" xlink:to="loc_dei_EntityDomain_0c66e707-db4a-48df-86e8-0147e7ee9ccb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_db091f71-5b0a-4548-895c-41cb73a92417" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ExpectedAmortizationExpenseLineItems_4543e043-7340-4fd5-9c15-86abd3f0383b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_db091f71-5b0a-4548-895c-41cb73a92417" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_f9518203-ce22-4f38-83dd-6bb33dfe1eee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ExpectedAmortizationExpenseLineItems_4543e043-7340-4fd5-9c15-86abd3f0383b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_f9518203-ce22-4f38-83dd-6bb33dfe1eee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_5b6dad8e-bd77-49d1-825e-ef6bf31108c6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ExpectedAmortizationExpenseLineItems_4543e043-7340-4fd5-9c15-86abd3f0383b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_5b6dad8e-bd77-49d1-825e-ef6bf31108c6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_dbf680fb-d729-47e3-81e5-459084fb8abc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ExpectedAmortizationExpenseLineItems_4543e043-7340-4fd5-9c15-86abd3f0383b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_dbf680fb-d729-47e3-81e5-459084fb8abc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_ba4abd76-5bc7-464c-a090-3b69fc3a386f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ExpectedAmortizationExpenseLineItems_4543e043-7340-4fd5-9c15-86abd3f0383b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_ba4abd76-5bc7-464c-a090-3b69fc3a386f" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/AccumulatedOtherComprehensiveLossDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#AccumulatedOtherComprehensiveLossDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/AccumulatedOtherComprehensiveLossDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_95b07023-cbf6-45b0-8086-3c9a67911828" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_4858b33e-2e21-4e05-8c67-32745547656e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_95b07023-cbf6-45b0-8086-3c9a67911828" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_4858b33e-2e21-4e05-8c67-32745547656e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_c19492b0-3d44-4c6d-b777-4099d77acff0" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_4858b33e-2e21-4e05-8c67-32745547656e" xlink:to="loc_dei_LegalEntityAxis_c19492b0-3d44-4c6d-b777-4099d77acff0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_c19492b0-3d44-4c6d-b777-4099d77acff0_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_c19492b0-3d44-4c6d-b777-4099d77acff0" xlink:to="loc_dei_EntityDomain_c19492b0-3d44-4c6d-b777-4099d77acff0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_e101f5ae-2c94-40f6-a301-334d9a815fab" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_c19492b0-3d44-4c6d-b777-4099d77acff0" xlink:to="loc_dei_EntityDomain_e101f5ae-2c94-40f6-a301-334d9a815fab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax_6948269f-a02a-40fe-8194-fecfac0925d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_95b07023-cbf6-45b0-8086-3c9a67911828" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax_6948269f-a02a-40fe-8194-fecfac0925d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AociLossCashFlowHedgeCumulativeGainLossAfterTax_013b3d45-108a-4343-9963-389e7805daf9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AociLossCashFlowHedgeCumulativeGainLossAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_95b07023-cbf6-45b0-8086-3c9a67911828" xlink:to="loc_us-gaap_AociLossCashFlowHedgeCumulativeGainLossAfterTax_013b3d45-108a-4343-9963-389e7805daf9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_36159b94-8163-4d7f-99ed-4f8caf213831" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_95b07023-cbf6-45b0-8086-3c9a67911828" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_36159b94-8163-4d7f-99ed-4f8caf213831" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/DebtDebtOutstandingandAverageInterestRatesDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#DebtDebtOutstandingandAverageInterestRatesDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/DebtDebtOutstandingandAverageInterestRatesDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_e66425ba-0d79-484a-8a64-c59e9b5b59e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_04abb742-f159-4d98-a802-0ba936647d05" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_e66425ba-0d79-484a-8a64-c59e9b5b59e3" xlink:to="loc_us-gaap_DebtInstrumentTable_04abb742-f159-4d98-a802-0ba936647d05" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_2defcf82-8473-46b4-b3ed-5d029f1208c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_04abb742-f159-4d98-a802-0ba936647d05" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_2defcf82-8473-46b4-b3ed-5d029f1208c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_2defcf82-8473-46b4-b3ed-5d029f1208c3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_2defcf82-8473-46b4-b3ed-5d029f1208c3" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_2defcf82-8473-46b4-b3ed-5d029f1208c3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_474fb07f-4c0a-48e9-ab23-f766a35ca7d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_2defcf82-8473-46b4-b3ed-5d029f1208c3" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_474fb07f-4c0a-48e9-ab23-f766a35ca7d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_044b545b-a641-4811-8251-1dc908ff6b05" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_474fb07f-4c0a-48e9-ab23-f766a35ca7d8" xlink:to="loc_us-gaap_LineOfCreditMember_044b545b-a641-4811-8251-1dc908ff6b05" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TermLoansMember_8037231d-9950-4cb3-9843-911ced86a5d4" xlink:href="pnr-20231231.xsd#pnr_TermLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_474fb07f-4c0a-48e9-ab23-f766a35ca7d8" xlink:to="loc_pnr_TermLoansMember_8037231d-9950-4cb3-9843-911ced86a5d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_b919a29a-cae7-4221-8ee3-884d465f8475" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_474fb07f-4c0a-48e9-ab23-f766a35ca7d8" xlink:to="loc_us-gaap_SeniorNotesMember_b919a29a-cae7-4221-8ee3-884d465f8475" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_e5cda14d-86a3-4593-b8fd-f8a04467e053" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_04abb742-f159-4d98-a802-0ba936647d05" xlink:to="loc_us-gaap_DebtInstrumentAxis_e5cda14d-86a3-4593-b8fd-f8a04467e053" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_e5cda14d-86a3-4593-b8fd-f8a04467e053_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_e5cda14d-86a3-4593-b8fd-f8a04467e053" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_e5cda14d-86a3-4593-b8fd-f8a04467e053_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_febeab01-0166-4501-85a0-e8b77e5ffd64" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_e5cda14d-86a3-4593-b8fd-f8a04467e053" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_febeab01-0166-4501-85a0-e8b77e5ffd64" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TermLoans1033DueIn2024Member_78e5a669-7909-418e-a27a-c75419cc288f" xlink:href="pnr-20231231.xsd#pnr_TermLoans1033DueIn2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_febeab01-0166-4501-85a0-e8b77e5ffd64" xlink:to="loc_pnr_TermLoans1033DueIn2024Member_78e5a669-7909-418e-a27a-c75419cc288f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SeniorNotesFourPointSixFivePercentDueTwentyTwentyFiveMember_c420b80e-58b6-48a1-b562-2ee350186c08" xlink:href="pnr-20231231.xsd#pnr_SeniorNotesFourPointSixFivePercentDueTwentyTwentyFiveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_febeab01-0166-4501-85a0-e8b77e5ffd64" xlink:to="loc_pnr_SeniorNotesFourPointSixFivePercentDueTwentyTwentyFiveMember_c420b80e-58b6-48a1-b562-2ee350186c08" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SeniorNotes4.500duein2029Member_6674aaa3-3060-4125-a552-2473e01db1eb" xlink:href="pnr-20231231.xsd#pnr_SeniorNotes4.500duein2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_febeab01-0166-4501-85a0-e8b77e5ffd64" xlink:to="loc_pnr_SeniorNotes4.500duein2029Member_6674aaa3-3060-4125-a552-2473e01db1eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_A5YearTermLoanFacilityMember_8a890ee3-3e47-4e65-8ca6-6582326f0edb" xlink:href="pnr-20231231.xsd#pnr_A5YearTermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_febeab01-0166-4501-85a0-e8b77e5ffd64" xlink:to="loc_pnr_A5YearTermLoanFacilityMember_8a890ee3-3e47-4e65-8ca6-6582326f0edb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SeniorNotesFivePointNinePercentDueTwentyThirtyTwoMember_c3a4a5ea-4193-4f23-acf4-70d020d477be" xlink:href="pnr-20231231.xsd#pnr_SeniorNotesFivePointNinePercentDueTwentyThirtyTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_febeab01-0166-4501-85a0-e8b77e5ffd64" xlink:to="loc_pnr_SeniorNotesFivePointNinePercentDueTwentyThirtyTwoMember_c3a4a5ea-4193-4f23-acf4-70d020d477be" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_21bcb20e-4493-4a4e-a6fe-07494b59bbbb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_04abb742-f159-4d98-a802-0ba936647d05" xlink:to="loc_us-gaap_CreditFacilityAxis_21bcb20e-4493-4a4e-a6fe-07494b59bbbb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_21bcb20e-4493-4a4e-a6fe-07494b59bbbb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_21bcb20e-4493-4a4e-a6fe-07494b59bbbb" xlink:to="loc_us-gaap_CreditFacilityDomain_21bcb20e-4493-4a4e-a6fe-07494b59bbbb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_766b1f29-48e3-48cb-9719-7cd28c351ee3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_21bcb20e-4493-4a4e-a6fe-07494b59bbbb" xlink:to="loc_us-gaap_CreditFacilityDomain_766b1f29-48e3-48cb-9719-7cd28c351ee3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_cc161610-5607-45a2-8312-d67c02e4bca2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_766b1f29-48e3-48cb-9719-7cd28c351ee3" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_cc161610-5607-45a2-8312-d67c02e4bca2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_3370e35f-5d6e-4dc6-8f07-75ea15bf2597" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_e66425ba-0d79-484a-8a64-c59e9b5b59e3" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_3370e35f-5d6e-4dc6-8f07-75ea15bf2597" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_940c45e5-0e93-4bcc-a2ca-5416725cc024" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_e66425ba-0d79-484a-8a64-c59e9b5b59e3" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_940c45e5-0e93-4bcc-a2ca-5416725cc024" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_2a08849b-b2d6-4295-9c13-ef0ad1e05582" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_e66425ba-0d79-484a-8a64-c59e9b5b59e3" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_2a08849b-b2d6-4295-9c13-ef0ad1e05582" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_a9cdaef8-d8ed-48da-bc53-187e77a318d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_e66425ba-0d79-484a-8a64-c59e9b5b59e3" xlink:to="loc_us-gaap_LongTermDebt_a9cdaef8-d8ed-48da-bc53-187e77a318d8" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/DebtAdditionalInformationDetails" xlink:type="simple" xlink:href="pnr-20231231.xsd#DebtAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/DebtAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_0c7488eb-707c-4a04-ac8a-a67e8cabfb78" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_us-gaap_DebtInstrumentTable_0c7488eb-707c-4a04-ac8a-a67e8cabfb78" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_8b50937b-fe2d-47d6-afe2-9959ce4a0dca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c7488eb-707c-4a04-ac8a-a67e8cabfb78" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_8b50937b-fe2d-47d6-afe2-9959ce4a0dca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_8b50937b-fe2d-47d6-afe2-9959ce4a0dca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_8b50937b-fe2d-47d6-afe2-9959ce4a0dca" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_8b50937b-fe2d-47d6-afe2-9959ce4a0dca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_d7d3da39-1bb7-4434-97d3-c4fd373b5adf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_8b50937b-fe2d-47d6-afe2-9959ce4a0dca" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_d7d3da39-1bb7-4434-97d3-c4fd373b5adf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_9c06ff6c-c238-4020-b6e4-c01c52379826" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_d7d3da39-1bb7-4434-97d3-c4fd373b5adf" xlink:to="loc_us-gaap_LineOfCreditMember_9c06ff6c-c238-4020-b6e4-c01c52379826" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TermLoansMember_1d7cd78c-25b1-474a-bce3-4a5e469b48da" xlink:href="pnr-20231231.xsd#pnr_TermLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_d7d3da39-1bb7-4434-97d3-c4fd373b5adf" xlink:to="loc_pnr_TermLoansMember_1d7cd78c-25b1-474a-bce3-4a5e469b48da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_1dc71eba-727d-408d-b801-5277ed08f7e1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_d7d3da39-1bb7-4434-97d3-c4fd373b5adf" xlink:to="loc_us-gaap_SeniorNotesMember_1dc71eba-727d-408d-b801-5277ed08f7e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_5747a728-56ab-4e3f-b289-39dc277f7c6a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c7488eb-707c-4a04-ac8a-a67e8cabfb78" xlink:to="loc_us-gaap_CreditFacilityAxis_5747a728-56ab-4e3f-b289-39dc277f7c6a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_5747a728-56ab-4e3f-b289-39dc277f7c6a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_5747a728-56ab-4e3f-b289-39dc277f7c6a" xlink:to="loc_us-gaap_CreditFacilityDomain_5747a728-56ab-4e3f-b289-39dc277f7c6a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_f721bdf8-37b8-42f2-9be0-179f530a206b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_5747a728-56ab-4e3f-b289-39dc277f7c6a" xlink:to="loc_us-gaap_CreditFacilityDomain_f721bdf8-37b8-42f2-9be0-179f530a206b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_9e9515a5-0f83-4bee-8691-e7fa0a0f688a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_f721bdf8-37b8-42f2-9be0-179f530a206b" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_9e9515a5-0f83-4bee-8691-e7fa0a0f688a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_c9221887-88b8-4fdc-a226-49fe828c26a8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c7488eb-707c-4a04-ac8a-a67e8cabfb78" xlink:to="loc_us-gaap_DebtInstrumentAxis_c9221887-88b8-4fdc-a226-49fe828c26a8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_c9221887-88b8-4fdc-a226-49fe828c26a8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_c9221887-88b8-4fdc-a226-49fe828c26a8" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_c9221887-88b8-4fdc-a226-49fe828c26a8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_adfb65ab-b811-40ba-ac8d-f969c8fb0033" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_c9221887-88b8-4fdc-a226-49fe828c26a8" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_adfb65ab-b811-40ba-ac8d-f969c8fb0033" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TermLoans1033DueIn2024Member_5aa74413-221d-4587-9b8c-791020ab9153" xlink:href="pnr-20231231.xsd#pnr_TermLoans1033DueIn2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_adfb65ab-b811-40ba-ac8d-f969c8fb0033" xlink:to="loc_pnr_TermLoans1033DueIn2024Member_5aa74413-221d-4587-9b8c-791020ab9153" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_A5YearTermLoanFacilityMember_9b433236-b4d8-418b-80b8-d3a9bfa7bf90" xlink:href="pnr-20231231.xsd#pnr_A5YearTermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_adfb65ab-b811-40ba-ac8d-f969c8fb0033" xlink:to="loc_pnr_A5YearTermLoanFacilityMember_9b433236-b4d8-418b-80b8-d3a9bfa7bf90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SeniorNotesFivePointNinePercentDueTwentyThirtyTwoMember_68b635b8-f820-4b6f-a18e-2716e6ce33c2" xlink:href="pnr-20231231.xsd#pnr_SeniorNotesFivePointNinePercentDueTwentyThirtyTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_adfb65ab-b811-40ba-ac8d-f969c8fb0033" xlink:to="loc_pnr_SeniorNotesFivePointNinePercentDueTwentyThirtyTwoMember_68b635b8-f820-4b6f-a18e-2716e6ce33c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_416ee50e-3c51-4fa2-ad62-4cfad06040d5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c7488eb-707c-4a04-ac8a-a67e8cabfb78" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_416ee50e-3c51-4fa2-ad62-4cfad06040d5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_416ee50e-3c51-4fa2-ad62-4cfad06040d5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_416ee50e-3c51-4fa2-ad62-4cfad06040d5" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_416ee50e-3c51-4fa2-ad62-4cfad06040d5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_6453ef01-63bc-4ea8-a7fa-739109f67f0c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_416ee50e-3c51-4fa2-ad62-4cfad06040d5" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_6453ef01-63bc-4ea8-a7fa-739109f67f0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_OtherCreditFacilitiesMember_6691fd43-6bfe-474d-a90b-c731ee9fc747" xlink:href="pnr-20231231.xsd#pnr_OtherCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_6453ef01-63bc-4ea8-a7fa-739109f67f0c" xlink:to="loc_pnr_OtherCreditFacilitiesMember_6691fd43-6bfe-474d-a90b-c731ee9fc747" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_df5099cd-2809-4559-89e5-40a125faa22f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c7488eb-707c-4a04-ac8a-a67e8cabfb78" xlink:to="loc_srt_RangeAxis_df5099cd-2809-4559-89e5-40a125faa22f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_df5099cd-2809-4559-89e5-40a125faa22f_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_df5099cd-2809-4559-89e5-40a125faa22f" xlink:to="loc_srt_RangeMember_df5099cd-2809-4559-89e5-40a125faa22f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_4f3fdbfa-6a1c-4c32-acbd-2aa8c4c4906d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_df5099cd-2809-4559-89e5-40a125faa22f" xlink:to="loc_srt_RangeMember_4f3fdbfa-6a1c-4c32-acbd-2aa8c4c4906d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_68972194-92eb-4d98-a6ad-ff65d147699f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_4f3fdbfa-6a1c-4c32-acbd-2aa8c4c4906d" xlink:to="loc_srt_MinimumMember_68972194-92eb-4d98-a6ad-ff65d147699f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_ef6cb968-a33f-47c8-9a0f-2ee5eb623543" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_4f3fdbfa-6a1c-4c32-acbd-2aa8c4c4906d" xlink:to="loc_srt_MaximumMember_ef6cb968-a33f-47c8-9a0f-2ee5eb623543" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_46986130-2528-48db-8df5-74971c9c9159" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c7488eb-707c-4a04-ac8a-a67e8cabfb78" xlink:to="loc_srt_CounterpartyNameAxis_46986130-2528-48db-8df5-74971c9c9159" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_46986130-2528-48db-8df5-74971c9c9159_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_46986130-2528-48db-8df5-74971c9c9159" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_46986130-2528-48db-8df5-74971c9c9159_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_cd634e9f-821c-4992-853c-8746a413af4e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_46986130-2528-48db-8df5-74971c9c9159" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_cd634e9f-821c-4992-853c-8746a413af4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_PentairPentairFinanceSRlPFSAMember_7d4b44ff-f3cb-418a-99ce-249139957906" xlink:href="pnr-20231231.xsd#pnr_PentairPentairFinanceSRlPFSAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_cd634e9f-821c-4992-853c-8746a413af4e" xlink:to="loc_pnr_PentairPentairFinanceSRlPFSAMember_7d4b44ff-f3cb-418a-99ce-249139957906" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_aa0bfed1-6eba-4adf-9356-8c407a8e6a4f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c7488eb-707c-4a04-ac8a-a67e8cabfb78" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_aa0bfed1-6eba-4adf-9356-8c407a8e6a4f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_aa0bfed1-6eba-4adf-9356-8c407a8e6a4f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_aa0bfed1-6eba-4adf-9356-8c407a8e6a4f" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_aa0bfed1-6eba-4adf-9356-8c407a8e6a4f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_d5d7483e-be88-46d1-857f-e6f694fe607d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_aa0bfed1-6eba-4adf-9356-8c407a8e6a4f" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_d5d7483e-be88-46d1-857f-e6f694fe607d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_94234fd8-427f-4a2e-9e0d-98c76084d125" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_d5d7483e-be88-46d1-857f-e6f694fe607d" xlink:to="loc_us-gaap_SubsequentEventMember_94234fd8-427f-4a2e-9e0d-98c76084d125" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_7f37b5ae-72d1-4cc6-808e-9c4fd22200a8" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c7488eb-707c-4a04-ac8a-a67e8cabfb78" xlink:to="loc_srt_StatementScenarioAxis_7f37b5ae-72d1-4cc6-808e-9c4fd22200a8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_7f37b5ae-72d1-4cc6-808e-9c4fd22200a8_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_7f37b5ae-72d1-4cc6-808e-9c4fd22200a8" xlink:to="loc_srt_ScenarioUnspecifiedDomain_7f37b5ae-72d1-4cc6-808e-9c4fd22200a8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_257e5576-ffa9-4957-872d-971361c71050" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_7f37b5ae-72d1-4cc6-808e-9c4fd22200a8" xlink:to="loc_srt_ScenarioUnspecifiedDomain_257e5576-ffa9-4957-872d-971361c71050" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_6672c553-8c0c-40d7-b100-0561ab9025c2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_257e5576-ffa9-4957-872d-971361c71050" xlink:to="loc_srt_ScenarioForecastMember_6672c553-8c0c-40d7-b100-0561ab9025c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_b89a6793-f086-4652-b6fc-635ea8606b5d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_b89a6793-f086-4652-b6fc-635ea8606b5d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_2868785f-baf4-4a09-8508-0e1190a1e1c7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_2868785f-baf4-4a09-8508-0e1190a1e1c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_5575c23d-0b6e-4935-9ed0-4d5c735e746d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_5575c23d-0b6e-4935-9ed0-4d5c735e746d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_LineofCreditFacilityAccordionFeatureIncreaseLimit_611c1f3e-29b0-4cb2-8aaf-68e709970d45" xlink:href="pnr-20231231.xsd#pnr_LineofCreditFacilityAccordionFeatureIncreaseLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_pnr_LineofCreditFacilityAccordionFeatureIncreaseLimit_611c1f3e-29b0-4cb2-8aaf-68e709970d45" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPayment_8cabedb0-8ed4-4573-ac84-a78b6c326c28" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentPeriodicPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPayment_8cabedb0-8ed4-4573-ac84-a78b6c326c28" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_ed855ebb-757f-494b-8ee9-065ac4bcbc5b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_ed855ebb-757f-494b-8ee9-065ac4bcbc5b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DebtInstrumentCovenantUnrestrictedCash_327dd92d-d4eb-4b60-a77a-8070fb80527e" xlink:href="pnr-20231231.xsd#pnr_DebtInstrumentCovenantUnrestrictedCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_pnr_DebtInstrumentCovenantUnrestrictedCash_327dd92d-d4eb-4b60-a77a-8070fb80527e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DebtInstrumentLeverageRatioCovenant_9216964e-d410-43d7-bce0-eda71691486f" xlink:href="pnr-20231231.xsd#pnr_DebtInstrumentLeverageRatioCovenant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_pnr_DebtInstrumentLeverageRatioCovenant_9216964e-d410-43d7-bce0-eda71691486f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DebtInstrumentCovenantNumberOfTestingPeriods_bf48332a-a9aa-4587-a88b-1143cc04d4a9" xlink:href="pnr-20231231.xsd#pnr_DebtInstrumentCovenantNumberOfTestingPeriods"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_pnr_DebtInstrumentCovenantNumberOfTestingPeriods_bf48332a-a9aa-4587-a88b-1143cc04d4a9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DebtInstrumentEBITDARatioCovenant_21f5507d-0ffb-423a-b22a-92deaa0509e6" xlink:href="pnr-20231231.xsd#pnr_DebtInstrumentEBITDARatioCovenant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_pnr_DebtInstrumentEBITDARatioCovenant_21f5507d-0ffb-423a-b22a-92deaa0509e6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_4279b295-6f01-480f-b52f-aef11e300d1f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_us-gaap_LineOfCredit_4279b295-6f01-480f-b52f-aef11e300d1f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_26bdc0f2-99f7-47e6-8326-8297007c8805" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9146c468-7fda-4c9a-b73d-ad8e948e0d46" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_26bdc0f2-99f7-47e6-8326-8297007c8805" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/DerivativesandFinancialInstrumentsAdditionalInformationDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#DerivativesandFinancialInstrumentsAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/DerivativesandFinancialInstrumentsAdditionalInformationDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:href="pnr-20231231.xsd#pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureTable_8c932d67-f505-4217-8836-bbb72683dfb6" xlink:href="pnr-20231231.xsd#pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureTable_8c932d67-f505-4217-8836-bbb72683dfb6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_ffd40ff9-3090-4128-8b8c-427fa0066943" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureTable_8c932d67-f505-4217-8836-bbb72683dfb6" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_ffd40ff9-3090-4128-8b8c-427fa0066943" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_ffd40ff9-3090-4128-8b8c-427fa0066943_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_ffd40ff9-3090-4128-8b8c-427fa0066943" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_ffd40ff9-3090-4128-8b8c-427fa0066943_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_58432fa1-7a26-45f4-9b5b-68069b0973b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_ffd40ff9-3090-4128-8b8c-427fa0066943" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_58432fa1-7a26-45f4-9b5b-68069b0973b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_cb968714-682a-44f1-be97-2b999d95ab7b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_58432fa1-7a26-45f4-9b5b-68069b0973b8" xlink:to="loc_us-gaap_SeniorNotesMember_cb968714-682a-44f1-be97-2b999d95ab7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_3faeaa81-63a3-4f87-9b3d-161cb49ff5b7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureTable_8c932d67-f505-4217-8836-bbb72683dfb6" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_3faeaa81-63a3-4f87-9b3d-161cb49ff5b7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_3faeaa81-63a3-4f87-9b3d-161cb49ff5b7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_3faeaa81-63a3-4f87-9b3d-161cb49ff5b7" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_3faeaa81-63a3-4f87-9b3d-161cb49ff5b7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_2b1a5626-179f-423c-86a9-0f897d08ef39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_3faeaa81-63a3-4f87-9b3d-161cb49ff5b7" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_2b1a5626-179f-423c-86a9-0f897d08ef39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_81ec5ddc-6a92-4354-8757-7c4e6fcce224" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2b1a5626-179f-423c-86a9-0f897d08ef39" xlink:to="loc_us-gaap_ForeignExchangeContractMember_81ec5ddc-6a92-4354-8757-7c4e6fcce224" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrencySwapMember_06ef8426-6357-4379-80fc-f7b123957698" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CurrencySwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2b1a5626-179f-423c-86a9-0f897d08ef39" xlink:to="loc_us-gaap_CurrencySwapMember_06ef8426-6357-4379-80fc-f7b123957698" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_CrossCurrencySwapOneMember_fdb7f59e-4697-4029-9976-d4acd6f4e555" xlink:href="pnr-20231231.xsd#pnr_CrossCurrencySwapOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CurrencySwapMember_06ef8426-6357-4379-80fc-f7b123957698" xlink:to="loc_pnr_CrossCurrencySwapOneMember_fdb7f59e-4697-4029-9976-d4acd6f4e555" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_CrossCurrencySwapsTwoMember_954739d0-8924-4509-9183-86d608ca0f4b" xlink:href="pnr-20231231.xsd#pnr_CrossCurrencySwapsTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CurrencySwapMember_06ef8426-6357-4379-80fc-f7b123957698" xlink:to="loc_pnr_CrossCurrencySwapsTwoMember_954739d0-8924-4509-9183-86d608ca0f4b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_InterestRateSwapAndInterestRateCollarMember_1c50b767-dc49-40fb-ab91-31c4521560a5" xlink:href="pnr-20231231.xsd#pnr_InterestRateSwapAndInterestRateCollarMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2b1a5626-179f-423c-86a9-0f897d08ef39" xlink:to="loc_pnr_InterestRateSwapAndInterestRateCollarMember_1c50b767-dc49-40fb-ab91-31c4521560a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_de005dc4-ee05-405d-a9ee-8fc5b1275efa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_InterestRateSwapAndInterestRateCollarMember_1c50b767-dc49-40fb-ab91-31c4521560a5" xlink:to="loc_us-gaap_InterestRateSwapMember_de005dc4-ee05-405d-a9ee-8fc5b1275efa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_InterestRateCollarMember_ebaca405-cd18-4d90-8baf-74f7013d7b76" xlink:href="pnr-20231231.xsd#pnr_InterestRateCollarMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_InterestRateSwapAndInterestRateCollarMember_1c50b767-dc49-40fb-ab91-31c4521560a5" xlink:to="loc_pnr_InterestRateCollarMember_ebaca405-cd18-4d90-8baf-74f7013d7b76" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_1995a992-5631-47f8-a377-839438c13e2e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureTable_8c932d67-f505-4217-8836-bbb72683dfb6" xlink:to="loc_srt_StatementScenarioAxis_1995a992-5631-47f8-a377-839438c13e2e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_1995a992-5631-47f8-a377-839438c13e2e_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_1995a992-5631-47f8-a377-839438c13e2e" xlink:to="loc_srt_ScenarioUnspecifiedDomain_1995a992-5631-47f8-a377-839438c13e2e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_b656e960-095f-4a7d-b7f2-1cfca980c47a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_1995a992-5631-47f8-a377-839438c13e2e" xlink:to="loc_srt_ScenarioUnspecifiedDomain_b656e960-095f-4a7d-b7f2-1cfca980c47a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_60ef69b8-f8da-4050-a20d-a68ab2d51dbc" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_b656e960-095f-4a7d-b7f2-1cfca980c47a" xlink:to="loc_srt_ScenarioForecastMember_60ef69b8-f8da-4050-a20d-a68ab2d51dbc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_0bebd695-eb23-4ebd-b0c2-9c3b03874fb8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureTable_8c932d67-f505-4217-8836-bbb72683dfb6" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_0bebd695-eb23-4ebd-b0c2-9c3b03874fb8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_0bebd695-eb23-4ebd-b0c2-9c3b03874fb8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_0bebd695-eb23-4ebd-b0c2-9c3b03874fb8" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_0bebd695-eb23-4ebd-b0c2-9c3b03874fb8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_b0bdf760-e8ff-48d1-9a07-a107d4de59a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_0bebd695-eb23-4ebd-b0c2-9c3b03874fb8" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_b0bdf760-e8ff-48d1-9a07-a107d4de59a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_4179e6c2-21d2-414a-97be-4136043510b3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_b0bdf760-e8ff-48d1-9a07-a107d4de59a9" xlink:to="loc_us-gaap_SubsequentEventMember_4179e6c2-21d2-414a-97be-4136043510b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_e99d2a70-4f1f-4a4e-9c40-88b900d5f955" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureTable_8c932d67-f505-4217-8836-bbb72683dfb6" xlink:to="loc_us-gaap_HedgingDesignationAxis_e99d2a70-4f1f-4a4e-9c40-88b900d5f955" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_e99d2a70-4f1f-4a4e-9c40-88b900d5f955_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_e99d2a70-4f1f-4a4e-9c40-88b900d5f955" xlink:to="loc_us-gaap_HedgingDesignationDomain_e99d2a70-4f1f-4a4e-9c40-88b900d5f955_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_24091332-8ce5-4336-9049-7258a5a4ce12" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_e99d2a70-4f1f-4a4e-9c40-88b900d5f955" xlink:to="loc_us-gaap_HedgingDesignationDomain_24091332-8ce5-4336-9049-7258a5a4ce12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_817d9972-f63d-42c7-a19f-998a057c7242" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_24091332-8ce5-4336-9049-7258a5a4ce12" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_817d9972-f63d-42c7-a19f-998a057c7242" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_075a4c76-030e-408d-a98a-be6215627ae7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureTable_8c932d67-f505-4217-8836-bbb72683dfb6" xlink:to="loc_us-gaap_VariableRateAxis_075a4c76-030e-408d-a98a-be6215627ae7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_075a4c76-030e-408d-a98a-be6215627ae7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_075a4c76-030e-408d-a98a-be6215627ae7" xlink:to="loc_us-gaap_VariableRateDomain_075a4c76-030e-408d-a98a-be6215627ae7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_f21c74e2-9b86-43d2-90ab-055e2a565969" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_075a4c76-030e-408d-a98a-be6215627ae7" xlink:to="loc_us-gaap_VariableRateDomain_f21c74e2-9b86-43d2-90ab-055e2a565969" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember_d60e607d-60b0-4fc8-9716-b01bf1151e20" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_f21c74e2-9b86-43d2-90ab-055e2a565969" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember_d60e607d-60b0-4fc8-9716-b01bf1151e20" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_613b8a5a-bac5-4a72-92ba-8083a0c984e3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureTable_8c932d67-f505-4217-8836-bbb72683dfb6" xlink:to="loc_srt_RangeAxis_613b8a5a-bac5-4a72-92ba-8083a0c984e3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_613b8a5a-bac5-4a72-92ba-8083a0c984e3_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_613b8a5a-bac5-4a72-92ba-8083a0c984e3" xlink:to="loc_srt_RangeMember_613b8a5a-bac5-4a72-92ba-8083a0c984e3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_70e3fe41-6ea0-463a-9923-84a59d4705c9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_613b8a5a-bac5-4a72-92ba-8083a0c984e3" xlink:to="loc_srt_RangeMember_70e3fe41-6ea0-463a-9923-84a59d4705c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_687f3874-50ac-44f1-b1b6-3da48ea59f23" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_70e3fe41-6ea0-463a-9923-84a59d4705c9" xlink:to="loc_srt_MinimumMember_687f3874-50ac-44f1-b1b6-3da48ea59f23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_c15855e1-a519-495b-ba3a-99555b3fdf46" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_70e3fe41-6ea0-463a-9923-84a59d4705c9" xlink:to="loc_srt_MaximumMember_c15855e1-a519-495b-ba3a-99555b3fdf46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityNotionalAmount_68576b84-e630-43fc-a106-5c4e3ad235ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilityNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_us-gaap_DerivativeLiabilityNotionalAmount_68576b84-e630-43fc-a106-5c4e3ad235ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_0a97934b-79c3-4239-8b36-874e6fec60ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_us-gaap_DerivativeNotionalAmount_0a97934b-79c3-4239-8b36-874e6fec60ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax_f1c3de8a-a62d-480f-9cd5-4ffbdef85bc3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax_f1c3de8a-a62d-480f-9cd5-4ffbdef85bc3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_PaymentsFromHedge_d89b1983-da1c-4dfd-bdfe-5955040a1db4" xlink:href="pnr-20231231.xsd#pnr_PaymentsFromHedge"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_pnr_PaymentsFromHedge_d89b1983-da1c-4dfd-bdfe-5955040a1db4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_PaymentsFromHedgeInvestingActivities_eb0ba187-9c5b-4dfa-8257-76a9359b87c7" xlink:href="pnr-20231231.xsd#pnr_PaymentsFromHedgeInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_pnr_PaymentsFromHedgeInvestingActivities_eb0ba187-9c5b-4dfa-8257-76a9359b87c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromHedgeInvestingActivities_588cfe62-6de6-41be-9244-c5d2ede76c8f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromHedgeInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_us-gaap_ProceedsFromHedgeInvestingActivities_588cfe62-6de6-41be-9244-c5d2ede76c8f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ProceedsFromHedge_296d4e55-a31a-422b-ab7a-d57200aa2a61" xlink:href="pnr-20231231.xsd#pnr_ProceedsFromHedge"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_pnr_ProceedsFromHedge_296d4e55-a31a-422b-ab7a-d57200aa2a61" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ProceedsFromHedgeOperatingActivities_6e8863e1-ddde-42ff-b11b-7dafd14b3d64" xlink:href="pnr-20231231.xsd#pnr_ProceedsFromHedgeOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_pnr_ProceedsFromHedgeOperatingActivities_6e8863e1-ddde-42ff-b11b-7dafd14b3d64" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromHedgeFinancingActivities_aed0935d-ac1d-4dc2-98f0-de91e9e1b2c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromHedgeFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_us-gaap_ProceedsFromHedgeFinancingActivities_aed0935d-ac1d-4dc2-98f0-de91e9e1b2c9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeBasisSpreadOnVariableRate_d37cf208-c90d-444f-9823-8115b595b462" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeBasisSpreadOnVariableRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_us-gaap_DerivativeBasisSpreadOnVariableRate_d37cf208-c90d-444f-9823-8115b595b462" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTermOfContract_1d57290d-117e-4140-9a19-a981252ee6f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_us-gaap_DerivativeTermOfContract_1d57290d-117e-4140-9a19-a981252ee6f2" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AociLossCashFlowHedgeCumulativeGainLossAfterTax_dab44cef-f6cc-4000-b52a-82ac2ff9b4ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AociLossCashFlowHedgeCumulativeGainLossAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DerivativeInstrumentsAndHedgingActivitiesDisclosureLineItems_a26d25cc-9481-41b7-84ca-734764710f9b" xlink:to="loc_us-gaap_AociLossCashFlowHedgeCumulativeGainLossAfterTax_dab44cef-f6cc-4000-b52a-82ac2ff9b4ea" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/DerivativesandFinancialInstrumentsRecordedAmountsandEstimatedFairValuesofLongtermDebtandDerivativeFinancialInstrumentsDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#DerivativesandFinancialInstrumentsRecordedAmountsandEstimatedFairValuesofLongtermDebtandDerivativeFinancialInstrumentsDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/DerivativesandFinancialInstrumentsRecordedAmountsandEstimatedFairValuesofLongtermDebtandDerivativeFinancialInstrumentsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_b93bc0af-3f10-439c-bb4c-74f2609d0797" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_9c251509-9aba-49c1-8eb3-47acb83c31a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_b93bc0af-3f10-439c-bb4c-74f2609d0797" xlink:to="loc_us-gaap_DerivativeTable_9c251509-9aba-49c1-8eb3-47acb83c31a9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_11c76e4f-9df0-416c-9038-8617aecd7ece" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_9c251509-9aba-49c1-8eb3-47acb83c31a9" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_11c76e4f-9df0-416c-9038-8617aecd7ece" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_11c76e4f-9df0-416c-9038-8617aecd7ece_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_11c76e4f-9df0-416c-9038-8617aecd7ece" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_11c76e4f-9df0-416c-9038-8617aecd7ece_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_8a999d3a-77c5-494b-abb3-7f7ae8476bc9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_11c76e4f-9df0-416c-9038-8617aecd7ece" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_8a999d3a-77c5-494b-abb3-7f7ae8476bc9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_bcab5a5f-d1ce-4a7d-b995-6a46304817be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_8a999d3a-77c5-494b-abb3-7f7ae8476bc9" xlink:to="loc_us-gaap_SeniorNotesMember_bcab5a5f-d1ce-4a7d-b995-6a46304817be" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_84609892-bc6d-46fb-89a2-835dc61e275e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_9c251509-9aba-49c1-8eb3-47acb83c31a9" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_84609892-bc6d-46fb-89a2-835dc61e275e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_84609892-bc6d-46fb-89a2-835dc61e275e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_84609892-bc6d-46fb-89a2-835dc61e275e" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_84609892-bc6d-46fb-89a2-835dc61e275e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e799abb7-7067-45dc-ad30-736c3284c345" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_84609892-bc6d-46fb-89a2-835dc61e275e" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e799abb7-7067-45dc-ad30-736c3284c345" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_d52fa3fc-eac5-42b0-80dc-627da125dd54" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e799abb7-7067-45dc-ad30-736c3284c345" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_d52fa3fc-eac5-42b0-80dc-627da125dd54" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_eae8ac27-b442-4dae-a436-c7d5070d2403" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e799abb7-7067-45dc-ad30-736c3284c345" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_eae8ac27-b442-4dae-a436-c7d5070d2403" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_1d680bcc-158b-405b-93d5-b4841d87af02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e799abb7-7067-45dc-ad30-736c3284c345" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_1d680bcc-158b-405b-93d5-b4841d87af02" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtPercentageBearingVariableInterestAmount_6c7c4ffd-6c7f-4d7f-ba7c-eed67c110455" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtPercentageBearingVariableInterestAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_b93bc0af-3f10-439c-bb4c-74f2609d0797" xlink:to="loc_us-gaap_LongtermDebtPercentageBearingVariableInterestAmount_6c7c4ffd-6c7f-4d7f-ba7c-eed67c110455" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtPercentageBearingFixedInterestAmount_6aa23026-532e-4499-9b94-25b9f2b54221" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtPercentageBearingFixedInterestAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_b93bc0af-3f10-439c-bb4c-74f2609d0797" xlink:to="loc_us-gaap_LongtermDebtPercentageBearingFixedInterestAmount_6aa23026-532e-4499-9b94-25b9f2b54221" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_cff6e6ff-cc4a-4c70-aa53-a3817ba4b732" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_b93bc0af-3f10-439c-bb4c-74f2609d0797" xlink:to="loc_us-gaap_LongTermDebt_cff6e6ff-cc4a-4c70-aa53-a3817ba4b732" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/DerivativesandFinancialInstrumentsAssetsandLiabilitiesMeasuredatFairValueDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#DerivativesandFinancialInstrumentsAssetsandLiabilitiesMeasuredatFairValueDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/DerivativesandFinancialInstrumentsAssetsandLiabilitiesMeasuredatFairValueDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_04609406-9ceb-4a3f-876b-0f4bdeca09af" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_d0cd51cf-1f8a-41f0-81cf-b29dd63afe97" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_04609406-9ceb-4a3f-876b-0f4bdeca09af" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_d0cd51cf-1f8a-41f0-81cf-b29dd63afe97" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_b885c07e-1c04-4a23-911c-e1843994744a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_d0cd51cf-1f8a-41f0-81cf-b29dd63afe97" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_b885c07e-1c04-4a23-911c-e1843994744a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b885c07e-1c04-4a23-911c-e1843994744a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_b885c07e-1c04-4a23-911c-e1843994744a" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b885c07e-1c04-4a23-911c-e1843994744a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ed877d0b-4240-4b6c-a7df-205364a223fd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_b885c07e-1c04-4a23-911c-e1843994744a" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ed877d0b-4240-4b6c-a7df-205364a223fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_d634feb4-34b3-401f-9552-d47ba8909edc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ed877d0b-4240-4b6c-a7df-205364a223fd" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_d634feb4-34b3-401f-9552-d47ba8909edc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_4289f543-a506-4b9f-9072-3513b1653ff6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ed877d0b-4240-4b6c-a7df-205364a223fd" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_4289f543-a506-4b9f-9072-3513b1653ff6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_01b5e21d-bcf6-4b28-8cf1-418e20ba3c20" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ed877d0b-4240-4b6c-a7df-205364a223fd" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_01b5e21d-bcf6-4b28-8cf1-418e20ba3c20" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_a780f909-3d6b-47f8-9360-670dcf8f93ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ed877d0b-4240-4b6c-a7df-205364a223fd" xlink:to="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_a780f909-3d6b-47f8-9360-670dcf8f93ea" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_6f6d9dce-e07f-4e8f-ad4c-a88ba78ecae6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_d0cd51cf-1f8a-41f0-81cf-b29dd63afe97" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_6f6d9dce-e07f-4e8f-ad4c-a88ba78ecae6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_6f6d9dce-e07f-4e8f-ad4c-a88ba78ecae6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_6f6d9dce-e07f-4e8f-ad4c-a88ba78ecae6" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_6f6d9dce-e07f-4e8f-ad4c-a88ba78ecae6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_c9210026-f4ce-4747-97a3-4a489de664c2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_6f6d9dce-e07f-4e8f-ad4c-a88ba78ecae6" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_c9210026-f4ce-4747-97a3-4a489de664c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_235f4990-afd2-4479-84ee-2df9fba5a569" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_c9210026-f4ce-4747-97a3-4a489de664c2" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_235f4990-afd2-4479-84ee-2df9fba5a569" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_InterestRateContractAssetsFairValueDisclosure_5357a437-46f9-4dbc-81fe-8a5f7805dcc8" xlink:href="pnr-20231231.xsd#pnr_InterestRateContractAssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_04609406-9ceb-4a3f-876b-0f4bdeca09af" xlink:to="loc_pnr_InterestRateContractAssetsFairValueDisclosure_5357a437-46f9-4dbc-81fe-8a5f7805dcc8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyContractAssetFairValueDisclosure_03a5c23a-7577-4e5b-8586-544d5d778960" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignCurrencyContractAssetFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_04609406-9ceb-4a3f-876b-0f4bdeca09af" xlink:to="loc_us-gaap_ForeignCurrencyContractAssetFairValueDisclosure_03a5c23a-7577-4e5b-8586-544d5d778960" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_544e589a-3edc-4f63-bdf9-cc5b7f72cf83" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_04609406-9ceb-4a3f-876b-0f4bdeca09af" xlink:to="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_544e589a-3edc-4f63-bdf9-cc5b7f72cf83" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DeferredCompensationPlanAssetsFairValueDisclosure_94e598e2-d1d4-4ed2-9beb-4b58fdec8c31" xlink:href="pnr-20231231.xsd#pnr_DeferredCompensationPlanAssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_04609406-9ceb-4a3f-876b-0f4bdeca09af" xlink:to="loc_pnr_DeferredCompensationPlanAssetsFairValueDisclosure_94e598e2-d1d4-4ed2-9beb-4b58fdec8c31" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_66cc9192-ff63-44d4-8c77-4f5a981448ad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_04609406-9ceb-4a3f-876b-0f4bdeca09af" xlink:to="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_66cc9192-ff63-44d4-8c77-4f5a981448ad" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/IncomeTaxesIncomeLossBeforeIncomeTaxesandNoncontrollingInterestDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#IncomeTaxesIncomeLossBeforeIncomeTaxesandNoncontrollingInterestDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/IncomeTaxesIncomeLossBeforeIncomeTaxesandNoncontrollingInterestDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnr_IncomeTaxesLineItems_4149bda8-3bf8-4170-8c0f-052eacc15db6" xlink:href="pnr-20231231.xsd#pnr_IncomeTaxesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_IncomeTaxesTable_31f71d70-0f65-495b-8202-cfe895c52b13" xlink:href="pnr-20231231.xsd#pnr_IncomeTaxesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnr_IncomeTaxesLineItems_4149bda8-3bf8-4170-8c0f-052eacc15db6" xlink:to="loc_pnr_IncomeTaxesTable_31f71d70-0f65-495b-8202-cfe895c52b13" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_1892b2ce-5d2c-4664-b05f-f9ea3dd7d1e5" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_IncomeTaxesTable_31f71d70-0f65-495b-8202-cfe895c52b13" xlink:to="loc_dei_LegalEntityAxis_1892b2ce-5d2c-4664-b05f-f9ea3dd7d1e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_1892b2ce-5d2c-4664-b05f-f9ea3dd7d1e5_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_1892b2ce-5d2c-4664-b05f-f9ea3dd7d1e5" xlink:to="loc_dei_EntityDomain_1892b2ce-5d2c-4664-b05f-f9ea3dd7d1e5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_0ac3fa4f-59ca-4ce5-bcc6-100502e6e34b" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_1892b2ce-5d2c-4664-b05f-f9ea3dd7d1e5" xlink:to="loc_dei_EntityDomain_0ac3fa4f-59ca-4ce5-bcc6-100502e6e34b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_86ff12c6-482c-4a03-8318-fa04937dc2d2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_4149bda8-3bf8-4170-8c0f-052eacc15db6" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_86ff12c6-482c-4a03-8318-fa04937dc2d2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_bf97b184-f039-46eb-a6d9-cc2bd9a13b68" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_4149bda8-3bf8-4170-8c0f-052eacc15db6" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_bf97b184-f039-46eb-a6d9-cc2bd9a13b68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_bfd16728-89aa-472c-be72-0cce0a690c92" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_4149bda8-3bf8-4170-8c0f-052eacc15db6" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_bfd16728-89aa-472c-be72-0cce0a690c92" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_5e7696b2-d012-4a27-9aad-1b0fe3145d1e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_4149bda8-3bf8-4170-8c0f-052eacc15db6" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_5e7696b2-d012-4a27-9aad-1b0fe3145d1e" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/IncomeTaxesNarrativeDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#IncomeTaxesNarrativeDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/IncomeTaxesNarrativeDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:href="pnr-20231231.xsd#pnr_IncomeTaxesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_IncomeTaxesTable_093547a8-cfd8-46df-8a4e-1f2cbb4bcd48" xlink:href="pnr-20231231.xsd#pnr_IncomeTaxesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_pnr_IncomeTaxesTable_093547a8-cfd8-46df-8a4e-1f2cbb4bcd48" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_1d4dbf5e-8f79-4286-abe9-dfc6194fa772" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_IncomeTaxesTable_093547a8-cfd8-46df-8a4e-1f2cbb4bcd48" xlink:to="loc_srt_RangeAxis_1d4dbf5e-8f79-4286-abe9-dfc6194fa772" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_1d4dbf5e-8f79-4286-abe9-dfc6194fa772_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_1d4dbf5e-8f79-4286-abe9-dfc6194fa772" xlink:to="loc_srt_RangeMember_1d4dbf5e-8f79-4286-abe9-dfc6194fa772_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f87fc43a-c3b4-4169-9472-c5d18a180a0b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_1d4dbf5e-8f79-4286-abe9-dfc6194fa772" xlink:to="loc_srt_RangeMember_f87fc43a-c3b4-4169-9472-c5d18a180a0b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_c84b7080-767f-4690-b164-e14d50c71fdd" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f87fc43a-c3b4-4169-9472-c5d18a180a0b" xlink:to="loc_srt_MinimumMember_c84b7080-767f-4690-b164-e14d50c71fdd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_b588d158-68b7-4b00-8111-015bc7098a40" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f87fc43a-c3b4-4169-9472-c5d18a180a0b" xlink:to="loc_srt_MaximumMember_b588d158-68b7-4b00-8111-015bc7098a40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodAxis_3b6c23e9-45ab-4992-9d5a-1ed0509d6461" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TaxPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_IncomeTaxesTable_093547a8-cfd8-46df-8a4e-1f2cbb4bcd48" xlink:to="loc_us-gaap_TaxPeriodAxis_3b6c23e9-45ab-4992-9d5a-1ed0509d6461" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodDomain_3b6c23e9-45ab-4992-9d5a-1ed0509d6461_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TaxPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxPeriodAxis_3b6c23e9-45ab-4992-9d5a-1ed0509d6461" xlink:to="loc_us-gaap_TaxPeriodDomain_3b6c23e9-45ab-4992-9d5a-1ed0509d6461_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodDomain_a470d9cc-32c2-4ed7-a9dd-a1a3aa1a5b29" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TaxPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxPeriodAxis_3b6c23e9-45ab-4992-9d5a-1ed0509d6461" xlink:to="loc_us-gaap_TaxPeriodDomain_a470d9cc-32c2-4ed7-a9dd-a1a3aa1a5b29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxYear2017Member_190d423f-1be5-4b36-91aa-c1822ad75941" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TaxYear2017Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_a470d9cc-32c2-4ed7-a9dd-a1a3aa1a5b29" xlink:to="loc_us-gaap_TaxYear2017Member_190d423f-1be5-4b36-91aa-c1822ad75941" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxYear2023Member_b3a3fbcb-feb9-4ce6-a117-75bba9fc727e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TaxYear2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_a470d9cc-32c2-4ed7-a9dd-a1a3aa1a5b29" xlink:to="loc_us-gaap_TaxYear2023Member_b3a3fbcb-feb9-4ce6-a117-75bba9fc727e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_e18c75d9-1726-43ea-81cd-e954715c495f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_e18c75d9-1726-43ea-81cd-e954715c495f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_99426706-b4f7-41f5-85e6-94941839dc8d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_99426706-b4f7-41f5-85e6-94941839dc8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible_d2956eba-f935-4c79-89ef-70924535de6e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible_d2956eba-f935-4c79-89ef-70924535de6e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued_c67cee22-edf2-481f-b8ab-115aa31531a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued_c67cee22-edf2-481f-b8ab-115aa31531a3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued_aa4ddba9-c3b3-4b0a-a088-947d5bf8d8da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued_aa4ddba9-c3b3-4b0a-a088-947d5bf8d8da" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign_0c070a01-6008-4bce-a0b1-81a80c94e2e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign_0c070a01-6008-4bce-a0b1-81a80c94e2e4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_b8fdde33-7dd6-47da-addd-46578b88c4e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_b8fdde33-7dd6-47da-addd-46578b88c4e6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsValuationAllowance_2f25bc75-8c8f-460b-81b4-b845af4b724f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLossCarryforwardsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_us-gaap_OperatingLossCarryforwardsValuationAllowance_2f25bc75-8c8f-460b-81b4-b845af4b724f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsForeign_b625a150-fb17-4435-8068-8b5bfa93798c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsForeign"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsForeign_b625a150-fb17-4435-8068-8b5bfa93798c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DeferredTaxAssetsOperatingLossCarryforwardsForeignjurisdictionswithunlimitedtaxlosscarryforwardperiods_06386ed1-bace-419e-85e1-f599b7195956" xlink:href="pnr-20231231.xsd#pnr_DeferredTaxAssetsOperatingLossCarryforwardsForeignjurisdictionswithunlimitedtaxlosscarryforwardperiods"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_pnr_DeferredTaxAssetsOperatingLossCarryforwardsForeignjurisdictionswithunlimitedtaxlosscarryforwardperiods_06386ed1-bace-419e-85e1-f599b7195956" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocalNotSubjectToExpiration_4db8ba00-fffa-4699-8054-d1976528240c" xlink:href="pnr-20231231.xsd#pnr_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocalNotSubjectToExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_pnr_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocalNotSubjectToExpiration_4db8ba00-fffa-4699-8054-d1976528240c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal_30965a26-6c55-48b5-8aa8-4cb1260a0237" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal_30965a26-6c55-48b5-8aa8-4cb1260a0237" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilityNotRecognizedAmountOfUnrecognizedDeferredTaxLiabilityUndistributedEarningsOfForeignSubsidiaries_73d03bce-26f6-4960-ada1-a18b6a4bf185" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilityNotRecognizedAmountOfUnrecognizedDeferredTaxLiabilityUndistributedEarningsOfForeignSubsidiaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_IncomeTaxesLineItems_3fc04cda-1052-445d-a034-c30283a70c86" xlink:to="loc_us-gaap_DeferredTaxLiabilityNotRecognizedAmountOfUnrecognizedDeferredTaxLiabilityUndistributedEarningsOfForeignSubsidiaries_73d03bce-26f6-4960-ada1-a18b6a4bf185" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BenefitPlansObligationsandFundedStatusDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#BenefitPlansObligationsandFundedStatusDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BenefitPlansObligationsandFundedStatusDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_868d4321-c415-47d1-9228-752844325818" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_18c7dd14-6298-4669-ab17-19d12e81361c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_868d4321-c415-47d1-9228-752844325818" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_18c7dd14-6298-4669-ab17-19d12e81361c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_c7fa1786-7051-46fc-8309-dbdfef74e195" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_18c7dd14-6298-4669-ab17-19d12e81361c" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_c7fa1786-7051-46fc-8309-dbdfef74e195" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_c7fa1786-7051-46fc-8309-dbdfef74e195_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_c7fa1786-7051-46fc-8309-dbdfef74e195" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_c7fa1786-7051-46fc-8309-dbdfef74e195_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_72a39595-cbd1-4a06-b3f7-7ec063533ebb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_c7fa1786-7051-46fc-8309-dbdfef74e195" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_72a39595-cbd1-4a06-b3f7-7ec063533ebb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_634cfbb0-9d9b-49e6-8498-a588fcfe7f34" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_72a39595-cbd1-4a06-b3f7-7ec063533ebb" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_634cfbb0-9d9b-49e6-8498-a588fcfe7f34" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_9c8aaa4a-6072-4614-842a-0c4c71a996c1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_72a39595-cbd1-4a06-b3f7-7ec063533ebb" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_9c8aaa4a-6072-4614-842a-0c4c71a996c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ec85c46e-ebdc-4d3b-92f5-0e1aff85732d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_868d4321-c415-47d1-9228-752844325818" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ec85c46e-ebdc-4d3b-92f5-0e1aff85732d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_fc418113-1224-4b1d-b46e-8158f842de31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ec85c46e-ebdc-4d3b-92f5-0e1aff85732d" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_fc418113-1224-4b1d-b46e-8158f842de31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_c8b559b6-c278-455f-ba50-6403d91bc732" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ec85c46e-ebdc-4d3b-92f5-0e1aff85732d" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_c8b559b6-c278-455f-ba50-6403d91bc732" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_5af4121f-10f3-41de-bd17-9c8c1fa750bf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ec85c46e-ebdc-4d3b-92f5-0e1aff85732d" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_5af4121f-10f3-41de-bd17-9c8c1fa750bf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DefinedBenefitPlanRecognizedActuarialNetGainsLosses_5d03a81a-c413-401e-af86-4c2e9590fda8" xlink:href="pnr-20231231.xsd#pnr_DefinedBenefitPlanRecognizedActuarialNetGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ec85c46e-ebdc-4d3b-92f5-0e1aff85732d" xlink:to="loc_pnr_DefinedBenefitPlanRecognizedActuarialNetGainsLosses_5d03a81a-c413-401e-af86-4c2e9590fda8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_03074178-ee18-4f49-952f-250350d4fb1e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ec85c46e-ebdc-4d3b-92f5-0e1aff85732d" xlink:to="loc_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_03074178-ee18-4f49-952f-250350d4fb1e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_609075b5-e368-49e8-8e69-97ea1e1d94e8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ec85c46e-ebdc-4d3b-92f5-0e1aff85732d" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_609075b5-e368-49e8-8e69-97ea1e1d94e8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_49299217-30d6-421d-ba1a-901ce2925235" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_edf9c279-eb61-4602-ac54-cc8ebcca0765" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_868d4321-c415-47d1-9228-752844325818" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_edf9c279-eb61-4602-ac54-cc8ebcca0765" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_f2a85fd8-ccc9-487a-92c3-89cc7877667b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_edf9c279-eb61-4602-ac54-cc8ebcca0765" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_f2a85fd8-ccc9-487a-92c3-89cc7877667b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_fa7180f5-fcb2-4416-81c4-495e24b20ff8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_edf9c279-eb61-4602-ac54-cc8ebcca0765" xlink:to="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_fa7180f5-fcb2-4416-81c4-495e24b20ff8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_59cb0d4f-869f-41f0-b94e-fcffcda71e9a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_edf9c279-eb61-4602-ac54-cc8ebcca0765" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_59cb0d4f-869f-41f0-b94e-fcffcda71e9a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss_58f748bd-1276-4ec3-8041-729027fb6e8a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_edf9c279-eb61-4602-ac54-cc8ebcca0765" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss_58f748bd-1276-4ec3-8041-729027fb6e8a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_46b38bac-472f-4ed8-9496-7a177d48f26c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_edf9c279-eb61-4602-ac54-cc8ebcca0765" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_46b38bac-472f-4ed8-9496-7a177d48f26c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_9301aad4-d93e-4e71-96c3-446829ccced0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlanAbstract_3c18ce04-69fb-4a99-9173-014ec758c9e0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlanAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_868d4321-c415-47d1-9228-752844325818" xlink:to="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlanAbstract_3c18ce04-69fb-4a99-9173-014ec758c9e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_fbb29cd4-81f4-43e9-8963-77f8756d9b18" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlanAbstract_3c18ce04-69fb-4a99-9173-014ec758c9e0" xlink:to="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_fbb29cd4-81f4-43e9-8963-77f8756d9b18" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BenefitPlansAmountsRecordedinConsolidatedBalanceSheetsDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#BenefitPlansAmountsRecordedinConsolidatedBalanceSheetsDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BenefitPlansAmountsRecordedinConsolidatedBalanceSheetsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_64b2ca04-f163-4d2c-a62d-9380ead01b15" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_669a2fb3-2405-42f6-9be6-162c72511ef0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_64b2ca04-f163-4d2c-a62d-9380ead01b15" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_669a2fb3-2405-42f6-9be6-162c72511ef0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_e7ce90d4-ba47-4548-b5bd-5d6866fc6ae8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_669a2fb3-2405-42f6-9be6-162c72511ef0" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_e7ce90d4-ba47-4548-b5bd-5d6866fc6ae8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_e7ce90d4-ba47-4548-b5bd-5d6866fc6ae8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_e7ce90d4-ba47-4548-b5bd-5d6866fc6ae8" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_e7ce90d4-ba47-4548-b5bd-5d6866fc6ae8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_8d2e6821-dae4-4dc6-a5c0-5d40b47432c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_e7ce90d4-ba47-4548-b5bd-5d6866fc6ae8" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_8d2e6821-dae4-4dc6-a5c0-5d40b47432c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_665a7fb3-e612-4e03-8c44-a3a3e94789df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_8d2e6821-dae4-4dc6-a5c0-5d40b47432c4" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_665a7fb3-e612-4e03-8c44-a3a3e94789df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_1fcb38a9-1d2d-4a6e-9efa-c9989604debc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_8d2e6821-dae4-4dc6-a5c0-5d40b47432c4" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_1fcb38a9-1d2d-4a6e-9efa-c9989604debc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities_8fc26513-aa62-4481-8b76-7644ff39caad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_64b2ca04-f163-4d2c-a62d-9380ead01b15" xlink:to="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities_8fc26513-aa62-4481-8b76-7644ff39caad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_533808ed-c911-44fb-89d9-cee47ef4cdf5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_64b2ca04-f163-4d2c-a62d-9380ead01b15" xlink:to="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_533808ed-c911-44fb-89d9-cee47ef4cdf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent_525f19bf-2f10-415d-9489-528f1d222ee3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_64b2ca04-f163-4d2c-a62d-9380ead01b15" xlink:to="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent_525f19bf-2f10-415d-9489-528f1d222ee3" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BenefitPlansNarrativeDetails" xlink:type="simple" xlink:href="pnr-20231231.xsd#BenefitPlansNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BenefitPlansNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f806dc4c-fdf4-4d33-a7d0-29469b923350" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_32606b8d-11ff-42f0-9d93-7a0912a6538b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f806dc4c-fdf4-4d33-a7d0-29469b923350" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_32606b8d-11ff-42f0-9d93-7a0912a6538b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_b2a8760f-c643-4464-be65-e4ea70d15d06" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_32606b8d-11ff-42f0-9d93-7a0912a6538b" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_b2a8760f-c643-4464-be65-e4ea70d15d06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_b2a8760f-c643-4464-be65-e4ea70d15d06_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_b2a8760f-c643-4464-be65-e4ea70d15d06" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_b2a8760f-c643-4464-be65-e4ea70d15d06_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_0dca16e6-cebf-4a34-840e-bd6018c3df90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_b2a8760f-c643-4464-be65-e4ea70d15d06" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_0dca16e6-cebf-4a34-840e-bd6018c3df90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_3b8d71df-8316-421c-bec9-dac590b724c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_0dca16e6-cebf-4a34-840e-bd6018c3df90" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_3b8d71df-8316-421c-bec9-dac590b724c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DefinedContributionPensionandOtherPostretirementPlansAxis_ec533787-cad8-4817-a630-a80be22c7581" xlink:href="pnr-20231231.xsd#pnr_DefinedContributionPensionandOtherPostretirementPlansAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_32606b8d-11ff-42f0-9d93-7a0912a6538b" xlink:to="loc_pnr_DefinedContributionPensionandOtherPostretirementPlansAxis_ec533787-cad8-4817-a630-a80be22c7581" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DefinedContributionPensionAndOtherPostretirementPlansDomain_ec533787-cad8-4817-a630-a80be22c7581_default" xlink:href="pnr-20231231.xsd#pnr_DefinedContributionPensionAndOtherPostretirementPlansDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_pnr_DefinedContributionPensionandOtherPostretirementPlansAxis_ec533787-cad8-4817-a630-a80be22c7581" xlink:to="loc_pnr_DefinedContributionPensionAndOtherPostretirementPlansDomain_ec533787-cad8-4817-a630-a80be22c7581_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DefinedContributionPensionAndOtherPostretirementPlansDomain_e4285b11-2bbe-4908-a7de-22da8a6ba2e6" xlink:href="pnr-20231231.xsd#pnr_DefinedContributionPensionAndOtherPostretirementPlansDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_pnr_DefinedContributionPensionandOtherPostretirementPlansAxis_ec533787-cad8-4817-a630-a80be22c7581" xlink:to="loc_pnr_DefinedContributionPensionAndOtherPostretirementPlansDomain_e4285b11-2bbe-4908-a7de-22da8a6ba2e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_A401KPlanLegacyGroupOneMember_3145ad80-6491-4990-86b6-7abb8b8a193e" xlink:href="pnr-20231231.xsd#pnr_A401KPlanLegacyGroupOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DefinedContributionPensionAndOtherPostretirementPlansDomain_e4285b11-2bbe-4908-a7de-22da8a6ba2e6" xlink:to="loc_pnr_A401KPlanLegacyGroupOneMember_3145ad80-6491-4990-86b6-7abb8b8a193e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_A401KPlanLegacyGroupTwoMember_659b5aae-cf6f-447d-8d54-96ad2ca7da7f" xlink:href="pnr-20231231.xsd#pnr_A401KPlanLegacyGroupTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DefinedContributionPensionAndOtherPostretirementPlansDomain_e4285b11-2bbe-4908-a7de-22da8a6ba2e6" xlink:to="loc_pnr_A401KPlanLegacyGroupTwoMember_659b5aae-cf6f-447d-8d54-96ad2ca7da7f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_Flow401KPlanMember_545da198-6254-4382-b849-a9a723f5257d" xlink:href="pnr-20231231.xsd#pnr_Flow401KPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_DefinedContributionPensionAndOtherPostretirementPlansDomain_e4285b11-2bbe-4908-a7de-22da8a6ba2e6" xlink:to="loc_pnr_Flow401KPlanMember_545da198-6254-4382-b849-a9a723f5257d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation_873ff091-4280-47b3-8513-549b8b0df0fa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f806dc4c-fdf4-4d33-a7d0-29469b923350" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation_873ff091-4280-47b3-8513-549b8b0df0fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_HistoricalRateOfReturnOnPlanAssets_f81332a2-3b65-471e-8761-40cc322c63fb" xlink:href="pnr-20231231.xsd#pnr_HistoricalRateOfReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f806dc4c-fdf4-4d33-a7d0-29469b923350" xlink:to="loc_pnr_HistoricalRateOfReturnOnPlanAssets_f81332a2-3b65-471e-8761-40cc322c63fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_22a5ba54-1095-4f70-b6fd-4622d4f28d42" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f806dc4c-fdf4-4d33-a7d0-29469b923350" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_22a5ba54-1095-4f70-b6fd-4622d4f28d42" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear_6426e285-6d81-4ed1-86bf-caa691f81529" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f806dc4c-fdf4-4d33-a7d0-29469b923350" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear_6426e285-6d81-4ed1-86bf-caa691f81529" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_e9aa581a-4c54-4634-9c02-4116ad4960d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f806dc4c-fdf4-4d33-a7d0-29469b923350" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_e9aa581a-4c54-4634-9c02-4116ad4960d4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent_45225df3-2efa-4097-8211-23590245b662" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f806dc4c-fdf4-4d33-a7d0-29469b923350" xlink:to="loc_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent_45225df3-2efa-4097-8211-23590245b662" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeBenefitsAndShareBasedCompensation_a0bebc29-8ffd-4029-a17e-038791ba1075" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeBenefitsAndShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f806dc4c-fdf4-4d33-a7d0-29469b923350" xlink:to="loc_us-gaap_EmployeeBenefitsAndShareBasedCompensation_a0bebc29-8ffd-4029-a17e-038791ba1075" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDeferredCompensationArrangementsLiabilityCurrent_82d8f4b9-33dc-4acb-8e30-3bed859cb10e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherDeferredCompensationArrangementsLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f806dc4c-fdf4-4d33-a7d0-29469b923350" xlink:to="loc_us-gaap_OtherDeferredCompensationArrangementsLiabilityCurrent_82d8f4b9-33dc-4acb-8e30-3bed859cb10e" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BenefitPlansScheduleofAssumptionsDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#BenefitPlansScheduleofAssumptionsDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BenefitPlansScheduleofAssumptionsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_9bf6ebaa-b3ee-4e67-bb15-44235a406325" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_fcf750b5-7e70-4d5a-b3df-37cd31d33b5a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_9bf6ebaa-b3ee-4e67-bb15-44235a406325" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_fcf750b5-7e70-4d5a-b3df-37cd31d33b5a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_b63f05b3-1d23-4afe-b005-0327b1bb1ca4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_fcf750b5-7e70-4d5a-b3df-37cd31d33b5a" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_b63f05b3-1d23-4afe-b005-0327b1bb1ca4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_b63f05b3-1d23-4afe-b005-0327b1bb1ca4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_b63f05b3-1d23-4afe-b005-0327b1bb1ca4" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_b63f05b3-1d23-4afe-b005-0327b1bb1ca4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_3b43a41f-8c62-4625-a435-8fe656eb8dc2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_b63f05b3-1d23-4afe-b005-0327b1bb1ca4" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_3b43a41f-8c62-4625-a435-8fe656eb8dc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_703bd558-a076-44cd-8fbf-b77cc9d16657" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_3b43a41f-8c62-4625-a435-8fe656eb8dc2" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_703bd558-a076-44cd-8fbf-b77cc9d16657" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_ce2c8dcb-142f-4edf-9f8e-6be738d83195" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_3b43a41f-8c62-4625-a435-8fe656eb8dc2" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_ce2c8dcb-142f-4edf-9f8e-6be738d83195" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_c40ba24e-59fb-49c3-a510-7d287d01caef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_9bf6ebaa-b3ee-4e67-bb15-44235a406325" xlink:to="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_c40ba24e-59fb-49c3-a510-7d287d01caef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_a5bd56bd-7cd5-4966-b449-654c4d03555d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_c40ba24e-59fb-49c3-a510-7d287d01caef" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_a5bd56bd-7cd5-4966-b449-654c4d03555d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease_3045a962-80f8-41a2-9164-23100e6bfb59" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_c40ba24e-59fb-49c3-a510-7d287d01caef" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease_3045a962-80f8-41a2-9164-23100e6bfb59" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_42dbfcf7-7183-4630-a3f9-dd6a77cce313" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_9bf6ebaa-b3ee-4e67-bb15-44235a406325" xlink:to="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_42dbfcf7-7183-4630-a3f9-dd6a77cce313" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_08cb181e-df99-43f2-aef1-3b1fe7c83c62" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_42dbfcf7-7183-4630-a3f9-dd6a77cce313" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_08cb181e-df99-43f2-aef1-3b1fe7c83c62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_2d465f4d-103a-4e97-b770-bf9e10523643" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_42dbfcf7-7183-4630-a3f9-dd6a77cce313" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_2d465f4d-103a-4e97-b770-bf9e10523643" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease_99b8832a-f78d-401e-88a0-5f7b172558e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_42dbfcf7-7183-4630-a3f9-dd6a77cce313" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease_99b8832a-f78d-401e-88a0-5f7b172558e6" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BenefitPlansActualOverallAssetAllocationforUSAndNonUSPlansasComparedtoInvestmentPolicyGoalsDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#BenefitPlansActualOverallAssetAllocationforUSAndNonUSPlansasComparedtoInvestmentPolicyGoalsDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BenefitPlansActualOverallAssetAllocationforUSAndNonUSPlansasComparedtoInvestmentPolicyGoalsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d2459bbe-448a-406e-86c9-37e4b8ffe106" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_e81dda45-137d-40f1-b77d-a708d9390ed6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d2459bbe-448a-406e-86c9-37e4b8ffe106" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_e81dda45-137d-40f1-b77d-a708d9390ed6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_26817c97-7f50-412b-bc42-51ea91644ccb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_e81dda45-137d-40f1-b77d-a708d9390ed6" xlink:to="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_26817c97-7f50-412b-bc42-51ea91644ccb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_26817c97-7f50-412b-bc42-51ea91644ccb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_26817c97-7f50-412b-bc42-51ea91644ccb" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_26817c97-7f50-412b-bc42-51ea91644ccb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_0c568c68-bad7-436c-879b-fa84c4032ce8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_26817c97-7f50-412b-bc42-51ea91644ccb" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_0c568c68-bad7-436c-879b-fa84c4032ce8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FixedIncomeSecuritiesMember_b0e0a5f9-db20-4f55-aac0-1462d23a50e0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FixedIncomeSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_0c568c68-bad7-436c-879b-fa84c4032ce8" xlink:to="loc_us-gaap_FixedIncomeSecuritiesMember_b0e0a5f9-db20-4f55-aac0-1462d23a50e0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_OtherSecuritiesMember_7fe2e161-f69e-444a-97aa-634f33f62291" xlink:href="pnr-20231231.xsd#pnr_OtherSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_0c568c68-bad7-436c-879b-fa84c4032ce8" xlink:to="loc_pnr_OtherSecuritiesMember_7fe2e161-f69e-444a-97aa-634f33f62291" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsAbstract_55707beb-c160-4aa2-a770-a86b7994da65" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d2459bbe-448a-406e-86c9-37e4b8ffe106" xlink:to="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsAbstract_55707beb-c160-4aa2-a770-a86b7994da65" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations_3b0a35f2-af0e-4de8-9ff4-3f41ed080335" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsAbstract_55707beb-c160-4aa2-a770-a86b7994da65" xlink:to="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations_3b0a35f2-af0e-4de8-9ff4-3f41ed080335" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract_971428bb-e53c-4522-ac15-b9168a8e97ed" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d2459bbe-448a-406e-86c9-37e4b8ffe106" xlink:to="loc_us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract_971428bb-e53c-4522-ac15-b9168a8e97ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage_23f5d9ab-a2a3-4b5a-8ef4-b86a54f61207" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract_971428bb-e53c-4522-ac15-b9168a8e97ed" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage_23f5d9ab-a2a3-4b5a-8ef4-b86a54f61207" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BenefitPlansPlanAssetsUsingFairValueMethodologiesDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#BenefitPlansPlanAssetsUsingFairValueMethodologiesDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BenefitPlansPlanAssetsUsingFairValueMethodologiesDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4d65498e-ee6b-4894-908f-94a1224f040d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_4aa9dba7-c834-42ae-948a-199b15ab2728" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4d65498e-ee6b-4894-908f-94a1224f040d" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_4aa9dba7-c834-42ae-948a-199b15ab2728" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_c50e2485-0eab-4ccc-a045-a157ec4661a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_4aa9dba7-c834-42ae-948a-199b15ab2728" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_c50e2485-0eab-4ccc-a045-a157ec4661a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_c50e2485-0eab-4ccc-a045-a157ec4661a0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_c50e2485-0eab-4ccc-a045-a157ec4661a0" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_c50e2485-0eab-4ccc-a045-a157ec4661a0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_f97ba859-49c3-4ab8-8a98-a483e77ec1b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_c50e2485-0eab-4ccc-a045-a157ec4661a0" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_f97ba859-49c3-4ab8-8a98-a483e77ec1b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel12And3Member_b25b0d93-aa15-431e-9711-7521881584a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel12And3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_f97ba859-49c3-4ab8-8a98-a483e77ec1b1" xlink:to="loc_us-gaap_FairValueInputsLevel12And3Member_b25b0d93-aa15-431e-9711-7521881584a3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_037c1075-883e-4418-8526-df1e59db710a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLevel12And3Member_b25b0d93-aa15-431e-9711-7521881584a3" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_037c1075-883e-4418-8526-df1e59db710a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_154312bb-78f3-4437-829d-d8722c44cd3f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLevel12And3Member_b25b0d93-aa15-431e-9711-7521881584a3" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_154312bb-78f3-4437-829d-d8722c44cd3f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_45379b90-375c-416c-83be-c10f77d075d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLevel12And3Member_b25b0d93-aa15-431e-9711-7521881584a3" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_45379b90-375c-416c-83be-c10f77d075d9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_23b81b54-6fc3-4b1d-a664-a2fa84bf8f31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_f97ba859-49c3-4ab8-8a98-a483e77ec1b1" xlink:to="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_23b81b54-6fc3-4b1d-a664-a2fa84bf8f31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_18f07eb6-2357-4ee8-846c-cf42202a5ac8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_4aa9dba7-c834-42ae-948a-199b15ab2728" xlink:to="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_18f07eb6-2357-4ee8-846c-cf42202a5ac8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_18f07eb6-2357-4ee8-846c-cf42202a5ac8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_18f07eb6-2357-4ee8-846c-cf42202a5ac8" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_18f07eb6-2357-4ee8-846c-cf42202a5ac8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_b7931744-ee58-48f9-9ce3-5f4788ce36ec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_18f07eb6-2357-4ee8-846c-cf42202a5ac8" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_b7931744-ee58-48f9-9ce3-5f4788ce36ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanCashAndCashEquivalentsMember_56445a9f-9c60-44f8-b78d-5d2ca87291fa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_b7931744-ee58-48f9-9ce3-5f4788ce36ec" xlink:to="loc_us-gaap_DefinedBenefitPlanCashAndCashEquivalentsMember_56445a9f-9c60-44f8-b78d-5d2ca87291fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherInvestmentsMember_280c1bc5-6e6f-4dd2-ac60-9be49c6e4e72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherInvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_b7931744-ee58-48f9-9ce3-5f4788ce36ec" xlink:to="loc_us-gaap_OtherInvestmentsMember_280c1bc5-6e6f-4dd2-ac60-9be49c6e4e72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_ce2294ba-f399-48c3-8636-66664596f72d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4d65498e-ee6b-4894-908f-94a1224f040d" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_ce2294ba-f399-48c3-8636-66664596f72d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/BenefitPlansEstimatedfuturebenefitpaymentsDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#BenefitPlansEstimatedfuturebenefitpaymentsDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/BenefitPlansEstimatedfuturebenefitpaymentsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_c340c7ca-026c-4dd8-a0f5-7b2f123ff25c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_43cdc144-c45e-465e-8a8f-7730fe7aec1d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_c340c7ca-026c-4dd8-a0f5-7b2f123ff25c" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_43cdc144-c45e-465e-8a8f-7730fe7aec1d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_9cf7daa8-f5b5-4865-b710-92f020b60741" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_43cdc144-c45e-465e-8a8f-7730fe7aec1d" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_9cf7daa8-f5b5-4865-b710-92f020b60741" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_9cf7daa8-f5b5-4865-b710-92f020b60741_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_9cf7daa8-f5b5-4865-b710-92f020b60741" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_9cf7daa8-f5b5-4865-b710-92f020b60741_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_d532b8c5-281b-4d58-b0f6-3fa55ec3dc87" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_9cf7daa8-f5b5-4865-b710-92f020b60741" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_d532b8c5-281b-4d58-b0f6-3fa55ec3dc87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_b41c5ab9-2d7b-4ca2-b00b-adad2509c3f4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_d532b8c5-281b-4d58-b0f6-3fa55ec3dc87" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_b41c5ab9-2d7b-4ca2-b00b-adad2509c3f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_c04d410a-4232-46e3-9c58-b7d0a98567c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_d532b8c5-281b-4d58-b0f6-3fa55ec3dc87" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_c04d410a-4232-46e3-9c58-b7d0a98567c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_8971200e-0ee8-45e1-910f-3df817105eec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_c340c7ca-026c-4dd8-a0f5-7b2f123ff25c" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_8971200e-0ee8-45e1-910f-3df817105eec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_3eefabea-a9eb-4515-92b4-c2f41e8e3540" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_c340c7ca-026c-4dd8-a0f5-7b2f123ff25c" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_3eefabea-a9eb-4515-92b4-c2f41e8e3540" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_a704c2ae-af18-4ac9-9339-ce1f0a6d525f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_c340c7ca-026c-4dd8-a0f5-7b2f123ff25c" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_a704c2ae-af18-4ac9-9339-ce1f0a6d525f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_d827e617-bf98-426c-896d-360bf2178822" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_c340c7ca-026c-4dd8-a0f5-7b2f123ff25c" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_d827e617-bf98-426c-896d-360bf2178822" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_73247172-ee91-4d19-b5ba-0a6cc4663484" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_c340c7ca-026c-4dd8-a0f5-7b2f123ff25c" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_73247172-ee91-4d19-b5ba-0a6cc4663484" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DefinedBenefitPlanExpectedFutureBenefitPaymentsAfterYearFive_fbb44b1f-0f49-4344-b49e-8efc218bebbd" xlink:href="pnr-20231231.xsd#pnr_DefinedBenefitPlanExpectedFutureBenefitPaymentsAfterYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_c340c7ca-026c-4dd8-a0f5-7b2f123ff25c" xlink:to="loc_pnr_DefinedBenefitPlanExpectedFutureBenefitPaymentsAfterYearFive_fbb44b1f-0f49-4344-b49e-8efc218bebbd" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/ShareholdersEquityDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#ShareholdersEquityDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/ShareholdersEquityDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnr_StockholdersEquityNoteDisclosureLineItems_e6cc1460-5d97-4ddc-b6e5-cc7d6cfed22e" xlink:href="pnr-20231231.xsd#pnr_StockholdersEquityNoteDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_StockholdersEquityNoteDisclosureTable_d890948c-13e5-4c3f-9d5d-db3506a9e864" xlink:href="pnr-20231231.xsd#pnr_StockholdersEquityNoteDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_e6cc1460-5d97-4ddc-b6e5-cc7d6cfed22e" xlink:to="loc_pnr_StockholdersEquityNoteDisclosureTable_d890948c-13e5-4c3f-9d5d-db3506a9e864" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_FuturedividendsAxis_0acf97be-3737-49dc-9a5e-a6f9475248f3" xlink:href="pnr-20231231.xsd#pnr_FuturedividendsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureTable_d890948c-13e5-4c3f-9d5d-db3506a9e864" xlink:to="loc_pnr_FuturedividendsAxis_0acf97be-3737-49dc-9a5e-a6f9475248f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_FuturedividendsDomain_0acf97be-3737-49dc-9a5e-a6f9475248f3_default" xlink:href="pnr-20231231.xsd#pnr_FuturedividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_pnr_FuturedividendsAxis_0acf97be-3737-49dc-9a5e-a6f9475248f3" xlink:to="loc_pnr_FuturedividendsDomain_0acf97be-3737-49dc-9a5e-a6f9475248f3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_FuturedividendsDomain_ca339050-66ee-446b-92f8-7c85448a646c" xlink:href="pnr-20231231.xsd#pnr_FuturedividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_pnr_FuturedividendsAxis_0acf97be-3737-49dc-9a5e-a6f9475248f3" xlink:to="loc_pnr_FuturedividendsDomain_ca339050-66ee-446b-92f8-7c85448a646c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_e449841d-96bf-47d6-b80d-d960e9b35848" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureTable_d890948c-13e5-4c3f-9d5d-db3506a9e864" xlink:to="loc_srt_StatementScenarioAxis_e449841d-96bf-47d6-b80d-d960e9b35848" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_e449841d-96bf-47d6-b80d-d960e9b35848_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_e449841d-96bf-47d6-b80d-d960e9b35848" xlink:to="loc_srt_ScenarioUnspecifiedDomain_e449841d-96bf-47d6-b80d-d960e9b35848_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_f5ac7895-6666-4356-bd1e-0589ee51d4da" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_e449841d-96bf-47d6-b80d-d960e9b35848" xlink:to="loc_srt_ScenarioUnspecifiedDomain_f5ac7895-6666-4356-bd1e-0589ee51d4da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_bdf81ed6-6189-469a-9bf1-fc7f5677493b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureTable_d890948c-13e5-4c3f-9d5d-db3506a9e864" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_bdf81ed6-6189-469a-9bf1-fc7f5677493b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_bdf81ed6-6189-469a-9bf1-fc7f5677493b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_bdf81ed6-6189-469a-9bf1-fc7f5677493b" xlink:to="loc_us-gaap_EquityComponentDomain_bdf81ed6-6189-469a-9bf1-fc7f5677493b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_35896f28-4358-4a6e-9860-7e4deeec7fe4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_bdf81ed6-6189-469a-9bf1-fc7f5677493b" xlink:to="loc_us-gaap_EquityComponentDomain_35896f28-4358-4a6e-9860-7e4deeec7fe4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_8d439295-7224-46f0-8745-d939f98bc9af" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_35896f28-4358-4a6e-9860-7e4deeec7fe4" xlink:to="loc_us-gaap_CommonStockMember_8d439295-7224-46f0-8745-d939f98bc9af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_664d4f40-78d3-466c-a6d9-4f2e52de3dc0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_35896f28-4358-4a6e-9860-7e4deeec7fe4" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_664d4f40-78d3-466c-a6d9-4f2e52de3dc0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis_ab880aa2-6c4c-4a48-b620-740efc10d518" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareRepurchaseProgramAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureTable_d890948c-13e5-4c3f-9d5d-db3506a9e864" xlink:to="loc_us-gaap_ShareRepurchaseProgramAxis_ab880aa2-6c4c-4a48-b620-740efc10d518" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_ab880aa2-6c4c-4a48-b620-740efc10d518_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_ab880aa2-6c4c-4a48-b620-740efc10d518" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_ab880aa2-6c4c-4a48-b620-740efc10d518_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_b17811c3-b48b-486e-b96b-df08fffeb9f0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_ab880aa2-6c4c-4a48-b620-740efc10d518" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_b17811c3-b48b-486e-b96b-df08fffeb9f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_December2020ShareRepurchaseProgramMember_5bb1d10c-f272-4254-b439-4709948f6a1f" xlink:href="pnr-20231231.xsd#pnr_December2020ShareRepurchaseProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_b17811c3-b48b-486e-b96b-df08fffeb9f0" xlink:to="loc_pnr_December2020ShareRepurchaseProgramMember_5bb1d10c-f272-4254-b439-4709948f6a1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_a7874c25-ce18-46c0-b2de-8bb85f70b430" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_e6cc1460-5d97-4ddc-b6e5-cc7d6cfed22e" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_a7874c25-ce18-46c0-b2de-8bb85f70b430" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_2ba80d31-23f4-4d2b-b2c5-658f63ff4053" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_e6cc1460-5d97-4ddc-b6e5-cc7d6cfed22e" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_2ba80d31-23f4-4d2b-b2c5-658f63ff4053" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_8c7644c7-6377-446a-bd7c-682d38c10827" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_e6cc1460-5d97-4ddc-b6e5-cc7d6cfed22e" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_8c7644c7-6377-446a-bd7c-682d38c10827" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_6dc3df92-c0b6-481d-a279-1c35abf53e9d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_e6cc1460-5d97-4ddc-b6e5-cc7d6cfed22e" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_6dc3df92-c0b6-481d-a279-1c35abf53e9d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_dceda43f-ca40-47bc-8c48-bff2d6c8494a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_e6cc1460-5d97-4ddc-b6e5-cc7d6cfed22e" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_dceda43f-ca40-47bc-8c48-bff2d6c8494a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_82bc3ada-2338-4ecc-bf3b-8b15dcff5672" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_e6cc1460-5d97-4ddc-b6e5-cc7d6cfed22e" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_82bc3ada-2338-4ecc-bf3b-8b15dcff5672" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_IncreaseDecreasetoQuarterlyDividendRate_7165e6b2-8b70-49d4-b33d-55e49a937338" xlink:href="pnr-20231231.xsd#pnr_IncreaseDecreasetoQuarterlyDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_e6cc1460-5d97-4ddc-b6e5-cc7d6cfed22e" xlink:to="loc_pnr_IncreaseDecreasetoQuarterlyDividendRate_7165e6b2-8b70-49d4-b33d-55e49a937338" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableAmountPerShare_4032d343-19e1-4dad-a59c-0b1d1648b094" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsPayableAmountPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_e6cc1460-5d97-4ddc-b6e5-cc7d6cfed22e" xlink:to="loc_us-gaap_DividendsPayableAmountPerShare_4032d343-19e1-4dad-a59c-0b1d1648b094" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableCurrent_c1338b94-effa-44e9-b672-ff588c6f6560" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_e6cc1460-5d97-4ddc-b6e5-cc7d6cfed22e" xlink:to="loc_us-gaap_DividendsPayableCurrent_c1338b94-effa-44e9-b672-ff588c6f6560" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareCashPaid_63bb5033-d0b5-4629-b241-d070db8ac255" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockDividendsPerShareCashPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_e6cc1460-5d97-4ddc-b6e5-cc7d6cfed22e" xlink:to="loc_us-gaap_CommonStockDividendsPerShareCashPaid_63bb5033-d0b5-4629-b241-d070db8ac255" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/SharePlansSharebasedcompensationexpenseDetails" xlink:type="simple" xlink:href="pnr-20231231.xsd#SharePlansSharebasedcompensationexpenseDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/SharePlansSharebasedcompensationexpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_45e93efb-23a7-422b-8e91-43a00f92f584" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_2d7ffe3d-7a75-4209-b017-0ac6ab1661d5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_45e93efb-23a7-422b-8e91-43a00f92f584" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_2d7ffe3d-7a75-4209-b017-0ac6ab1661d5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_baeee069-5d07-4cdb-830d-24f53978933e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_2d7ffe3d-7a75-4209-b017-0ac6ab1661d5" xlink:to="loc_us-gaap_AwardTypeAxis_baeee069-5d07-4cdb-830d-24f53978933e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_baeee069-5d07-4cdb-830d-24f53978933e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_baeee069-5d07-4cdb-830d-24f53978933e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_baeee069-5d07-4cdb-830d-24f53978933e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_afecc651-2965-474b-99ae-a99b4e25ba9f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_baeee069-5d07-4cdb-830d-24f53978933e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_afecc651-2965-474b-99ae-a99b4e25ba9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_74a52224-4823-4482-9fd9-933bfdffbe53" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_afecc651-2965-474b-99ae-a99b4e25ba9f" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_74a52224-4823-4482-9fd9-933bfdffbe53" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockOptionMember_8f6c04b3-ee14-45c3-8bde-2a80bdaec600" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_afecc651-2965-474b-99ae-a99b4e25ba9f" xlink:to="loc_us-gaap_StockOptionMember_8f6c04b3-ee14-45c3-8bde-2a80bdaec600" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_2f0434f5-4293-4a5a-bb4b-164e408f1827" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_afecc651-2965-474b-99ae-a99b4e25ba9f" xlink:to="loc_us-gaap_PerformanceSharesMember_2f0434f5-4293-4a5a-bb4b-164e408f1827" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_2adb1fa6-2a3b-4901-b209-3f5999e30257" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_45e93efb-23a7-422b-8e91-43a00f92f584" xlink:to="loc_us-gaap_ShareBasedCompensation_2adb1fa6-2a3b-4901-b209-3f5999e30257" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/SharePlansAdditionalInformationDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#SharePlansAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/SharePlansAdditionalInformationDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_901f2d9f-e5e6-4b43-a124-455cbb04c746" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_adb65eb4-6b4b-432d-9246-f6260a996bc1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_901f2d9f-e5e6-4b43-a124-455cbb04c746" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_adb65eb4-6b4b-432d-9246-f6260a996bc1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_1431de0e-7831-47d4-9efb-c8547cedf330" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_adb65eb4-6b4b-432d-9246-f6260a996bc1" xlink:to="loc_us-gaap_AwardTypeAxis_1431de0e-7831-47d4-9efb-c8547cedf330" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1431de0e-7831-47d4-9efb-c8547cedf330_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_1431de0e-7831-47d4-9efb-c8547cedf330" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1431de0e-7831-47d4-9efb-c8547cedf330_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3fea93a1-dff9-426f-bbac-8c5414261419" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_1431de0e-7831-47d4-9efb-c8547cedf330" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3fea93a1-dff9-426f-bbac-8c5414261419" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_77ba30b9-32b2-4e29-8d3f-5761f483c244" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3fea93a1-dff9-426f-bbac-8c5414261419" xlink:to="loc_us-gaap_EmployeeStockOptionMember_77ba30b9-32b2-4e29-8d3f-5761f483c244" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_RestrictedStockAndRestrictedStockUnitsRSUsMember_562a09de-0555-4948-b1c2-cf5f222c4c98" xlink:href="pnr-20231231.xsd#pnr_RestrictedStockAndRestrictedStockUnitsRSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3fea93a1-dff9-426f-bbac-8c5414261419" xlink:to="loc_pnr_RestrictedStockAndRestrictedStockUnitsRSUsMember_562a09de-0555-4948-b1c2-cf5f222c4c98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_c170d312-684a-4a37-a847-53c95ba8672e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_RestrictedStockAndRestrictedStockUnitsRSUsMember_562a09de-0555-4948-b1c2-cf5f222c4c98" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_c170d312-684a-4a37-a847-53c95ba8672e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockOptionMember_347a892a-3392-4910-be00-3d8da372be6b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3fea93a1-dff9-426f-bbac-8c5414261419" xlink:to="loc_us-gaap_StockOptionMember_347a892a-3392-4910-be00-3d8da372be6b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockAppreciationRightsSARSMember_cc96441e-debe-46f3-96b7-8f26db2e5dbb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockAppreciationRightsSARSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3fea93a1-dff9-426f-bbac-8c5414261419" xlink:to="loc_us-gaap_StockAppreciationRightsSARSMember_cc96441e-debe-46f3-96b7-8f26db2e5dbb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_ac341d00-0b3f-4e52-a146-769f6f4ceb90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3fea93a1-dff9-426f-bbac-8c5414261419" xlink:to="loc_us-gaap_PerformanceSharesMember_ac341d00-0b3f-4e52-a146-769f6f4ceb90" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_cad85a60-b282-4877-b716-bd455889847f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_adb65eb4-6b4b-432d-9246-f6260a996bc1" xlink:to="loc_us-gaap_VestingAxis_cad85a60-b282-4877-b716-bd455889847f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_cad85a60-b282-4877-b716-bd455889847f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_cad85a60-b282-4877-b716-bd455889847f" xlink:to="loc_us-gaap_VestingDomain_cad85a60-b282-4877-b716-bd455889847f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_bd7ee360-3d3d-4cc3-bb94-d343369fd8bf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_cad85a60-b282-4877-b716-bd455889847f" xlink:to="loc_us-gaap_VestingDomain_bd7ee360-3d3d-4cc3-bb94-d343369fd8bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_051f860c-e5e8-4d3b-b896-d1a52179e24c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_bd7ee360-3d3d-4cc3-bb94-d343369fd8bf" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_051f860c-e5e8-4d3b-b896-d1a52179e24c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_6f9cb670-7035-4cd6-b353-054ace42d9b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_bd7ee360-3d3d-4cc3-bb94-d343369fd8bf" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_6f9cb670-7035-4cd6-b353-054ace42d9b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_dcb43566-27d1-4123-9df2-5abc6cf6a857" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationAwardTrancheThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_bd7ee360-3d3d-4cc3-bb94-d343369fd8bf" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_dcb43566-27d1-4123-9df2-5abc6cf6a857" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ShareIncentivePlansAbstract_f1065b1e-e25f-42d3-a69f-b1adb796abcb" xlink:href="pnr-20231231.xsd#pnr_ShareIncentivePlansAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_901f2d9f-e5e6-4b43-a124-455cbb04c746" xlink:to="loc_pnr_ShareIncentivePlansAbstract_f1065b1e-e25f-42d3-a69f-b1adb796abcb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_113eae8c-46fa-4ce8-bbed-e4c454e6995b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ShareIncentivePlansAbstract_f1065b1e-e25f-42d3-a69f-b1adb796abcb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_113eae8c-46fa-4ce8-bbed-e4c454e6995b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_bb914fe7-dcbe-4ee6-b87f-b478d0aa2d74" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_901f2d9f-e5e6-4b43-a124-455cbb04c746" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_bb914fe7-dcbe-4ee6-b87f-b478d0aa2d74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_668174bc-cd7e-4364-870b-49ea95bb2cac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_901f2d9f-e5e6-4b43-a124-455cbb04c746" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_668174bc-cd7e-4364-870b-49ea95bb2cac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiryPeriodFromDateOfGrant_ce6bcda0-eef5-459a-9635-714d0ade3140" xlink:href="pnr-20231231.xsd#pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiryPeriodFromDateOfGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_901f2d9f-e5e6-4b43-a124-455cbb04c746" xlink:to="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiryPeriodFromDateOfGrant_ce6bcda0-eef5-459a-9635-714d0ade3140" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_5e27bd2b-4b3f-4d2e-b27d-48bb2bb090c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_901f2d9f-e5e6-4b43-a124-455cbb04c746" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_5e27bd2b-4b3f-4d2e-b27d-48bb2bb090c0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_6cfd1a88-97af-4da3-a463-b17ec05100d2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_5e27bd2b-4b3f-4d2e-b27d-48bb2bb090c0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_6cfd1a88-97af-4da3-a463-b17ec05100d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_82082acf-ce3c-42f8-a391-f02b9134d746" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_5e27bd2b-4b3f-4d2e-b27d-48bb2bb090c0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_82082acf-ce3c-42f8-a391-f02b9134d746" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_8921e7d1-435e-46f8-93e3-069ae62485c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_5e27bd2b-4b3f-4d2e-b27d-48bb2bb090c0" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_8921e7d1-435e-46f8-93e3-069ae62485c3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_31d1c8f1-9b29-46b7-bd73-6bfa254b1cc9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_5e27bd2b-4b3f-4d2e-b27d-48bb2bb090c0" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_31d1c8f1-9b29-46b7-bd73-6bfa254b1cc9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromExerciseOfStockOptions_3a282f6e-2779-4c2d-9e67-766ba66e695f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromExerciseOfStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_5e27bd2b-4b3f-4d2e-b27d-48bb2bb090c0" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromExerciseOfStockOptions_3a282f6e-2779-4c2d-9e67-766ba66e695f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_35b966a3-cdf5-495e-83e0-a200fbefb1b3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_901f2d9f-e5e6-4b43-a124-455cbb04c746" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_35b966a3-cdf5-495e-83e0-a200fbefb1b3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_9fe1befa-36fc-4c57-b0b8-b6fd59c235a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_35b966a3-cdf5-495e-83e0-a200fbefb1b3" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_9fe1befa-36fc-4c57-b0b8-b6fd59c235a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_35eff564-257e-486f-b8ae-2486d217e61a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_35b966a3-cdf5-495e-83e0-a200fbefb1b3" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_35eff564-257e-486f-b8ae-2486d217e61a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_ec93b095-ac5a-4d23-94d2-2a977509416d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_35b966a3-cdf5-495e-83e0-a200fbefb1b3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_ec93b095-ac5a-4d23-94d2-2a977509416d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_4bb618d5-2cb2-4098-b4b6-a987f81488ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_35b966a3-cdf5-495e-83e0-a200fbefb1b3" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_4bb618d5-2cb2-4098-b4b6-a987f81488ef" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_5ee21de4-19c9-477c-affa-2cc21acb7d8b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_901f2d9f-e5e6-4b43-a124-455cbb04c746" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_5ee21de4-19c9-477c-affa-2cc21acb7d8b" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/SharePlansStockOptionActivityDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#SharePlansStockOptionActivityDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/SharePlansStockOptionActivityDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d38c65c-5df3-4ec1-95c6-2a917f4d6978" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a47b0d2e-ecdd-4601-81eb-668d2188e76d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d38c65c-5df3-4ec1-95c6-2a917f4d6978" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a47b0d2e-ecdd-4601-81eb-668d2188e76d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_759e2b29-b324-484e-887f-e17c23eb4c0f" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a47b0d2e-ecdd-4601-81eb-668d2188e76d" xlink:to="loc_dei_LegalEntityAxis_759e2b29-b324-484e-887f-e17c23eb4c0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_759e2b29-b324-484e-887f-e17c23eb4c0f_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_759e2b29-b324-484e-887f-e17c23eb4c0f" xlink:to="loc_dei_EntityDomain_759e2b29-b324-484e-887f-e17c23eb4c0f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_8b48e68b-8871-48b2-8f95-bbb09c3cc814" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_759e2b29-b324-484e-887f-e17c23eb4c0f" xlink:to="loc_dei_EntityDomain_8b48e68b-8871-48b2-8f95-bbb09c3cc814" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_52e7bc7e-4c38-4c51-afbb-10f41d71b44e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d38c65c-5df3-4ec1-95c6-2a917f4d6978" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_52e7bc7e-4c38-4c51-afbb-10f41d71b44e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_3068c29d-13f4-413b-987b-b691948ee56c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_52e7bc7e-4c38-4c51-afbb-10f41d71b44e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_3068c29d-13f4-413b-987b-b691948ee56c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_ff3b0274-c299-4d61-99f1-16638a3815c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_52e7bc7e-4c38-4c51-afbb-10f41d71b44e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_ff3b0274-c299-4d61-99f1-16638a3815c0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_24462465-3c01-4b24-8582-4827cc0e1d8d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_52e7bc7e-4c38-4c51-afbb-10f41d71b44e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_24462465-3c01-4b24-8582-4827cc0e1d8d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_944b65da-bedc-4840-8e8d-a4d82108727b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_f962c28b-9016-4817-a0ef-51d38c8cbb22" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d38c65c-5df3-4ec1-95c6-2a917f4d6978" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_f962c28b-9016-4817-a0ef-51d38c8cbb22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_5b583712-db92-43c1-8b25-736e15e0d6ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d38c65c-5df3-4ec1-95c6-2a917f4d6978" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_5b583712-db92-43c1-8b25-736e15e0d6ae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageExercisePriceAbstract_cc4e3d18-4589-4237-8733-b3ed590f63e5" xlink:href="pnr-20231231.xsd#pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageExercisePriceAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d38c65c-5df3-4ec1-95c6-2a917f4d6978" xlink:to="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageExercisePriceAbstract_cc4e3d18-4589-4237-8733-b3ed590f63e5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_b218b96b-0761-4524-8d55-0273bdaf1ad0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageExercisePriceAbstract_cc4e3d18-4589-4237-8733-b3ed590f63e5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_b218b96b-0761-4524-8d55-0273bdaf1ad0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_356e5b43-e5dd-4b8d-9498-1fe2253001f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageExercisePriceAbstract_cc4e3d18-4589-4237-8733-b3ed590f63e5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_356e5b43-e5dd-4b8d-9498-1fe2253001f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_d2d68db7-c905-416d-9338-e0071c204c45" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageExercisePriceAbstract_cc4e3d18-4589-4237-8733-b3ed590f63e5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_d2d68db7-c905-416d-9338-e0071c204c45" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_e6a3192a-3aa7-4abb-90a4-fc18b3fd5fa3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_bf6fcb04-9123-4782-8f99-dcbd199f3941" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d38c65c-5df3-4ec1-95c6-2a917f4d6978" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_bf6fcb04-9123-4782-8f99-dcbd199f3941" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_7426d66c-0096-4429-8363-40039db7f651" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d38c65c-5df3-4ec1-95c6-2a917f4d6978" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_7426d66c-0096-4429-8363-40039db7f651" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_92d50fce-2e76-4f0d-b6e3-18a871427a14" xlink:href="pnr-20231231.xsd#pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d38c65c-5df3-4ec1-95c6-2a917f4d6978" xlink:to="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_92d50fce-2e76-4f0d-b6e3-18a871427a14" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_5c2e5e00-f563-4a81-a8b9-5f0f2a906ebf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_92d50fce-2e76-4f0d-b6e3-18a871427a14" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_5c2e5e00-f563-4a81-a8b9-5f0f2a906ebf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_68d82c46-b872-47e6-8a26-99a56b17cb63" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_92d50fce-2e76-4f0d-b6e3-18a871427a14" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_68d82c46-b872-47e6-8a26-99a56b17cb63" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_8eb32cc2-93f5-4bbc-b67e-79d598a597c7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_92d50fce-2e76-4f0d-b6e3-18a871427a14" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_8eb32cc2-93f5-4bbc-b67e-79d598a597c7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract_5e681f60-4b41-4d59-968c-7ae804a789d8" xlink:href="pnr-20231231.xsd#pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d38c65c-5df3-4ec1-95c6-2a917f4d6978" xlink:to="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract_5e681f60-4b41-4d59-968c-7ae804a789d8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_83c643f4-f759-4713-a043-6ce380fc264c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract_5e681f60-4b41-4d59-968c-7ae804a789d8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_83c643f4-f759-4713-a043-6ce380fc264c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_6bd06cd0-ea41-4b9a-b775-e787789ebf07" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract_5e681f60-4b41-4d59-968c-7ae804a789d8" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_6bd06cd0-ea41-4b9a-b775-e787789ebf07" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_48ad91a4-12df-43e9-897e-221539c98991" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract_5e681f60-4b41-4d59-968c-7ae804a789d8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_48ad91a4-12df-43e9-897e-221539c98991" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/SharePlansRestrictedStockUnitsDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#SharePlansRestrictedStockUnitsDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/SharePlansRestrictedStockUnitsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bea56bfb-a842-4237-9132-6b394d183820" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_33942250-8b46-4b56-b2d8-28ea796014f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bea56bfb-a842-4237-9132-6b394d183820" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_33942250-8b46-4b56-b2d8-28ea796014f8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_8d1f60bd-93cd-4183-a639-3b73d3b44d44" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_33942250-8b46-4b56-b2d8-28ea796014f8" xlink:to="loc_us-gaap_AwardTypeAxis_8d1f60bd-93cd-4183-a639-3b73d3b44d44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8d1f60bd-93cd-4183-a639-3b73d3b44d44_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_8d1f60bd-93cd-4183-a639-3b73d3b44d44" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8d1f60bd-93cd-4183-a639-3b73d3b44d44_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6581c277-3149-411f-9c2a-6b7fa8ae5aa8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_8d1f60bd-93cd-4183-a639-3b73d3b44d44" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6581c277-3149-411f-9c2a-6b7fa8ae5aa8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_b9ea6239-dc2a-4b85-a6f0-9a7f60dac8ff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6581c277-3149-411f-9c2a-6b7fa8ae5aa8" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_b9ea6239-dc2a-4b85-a6f0-9a7f60dac8ff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_0f76a8fa-1852-44de-a95c-82e18a25c2ed" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bea56bfb-a842-4237-9132-6b394d183820" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_0f76a8fa-1852-44de-a95c-82e18a25c2ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_e95f6ea5-6bae-446a-8cb8-db3b8b4aef40" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_0f76a8fa-1852-44de-a95c-82e18a25c2ed" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_e95f6ea5-6bae-446a-8cb8-db3b8b4aef40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_ec023db2-62fe-476d-be79-01b07a41eb45" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_0f76a8fa-1852-44de-a95c-82e18a25c2ed" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_ec023db2-62fe-476d-be79-01b07a41eb45" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_491f8918-a5cd-419e-8b9f-1156daf3ce87" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_0f76a8fa-1852-44de-a95c-82e18a25c2ed" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_491f8918-a5cd-419e-8b9f-1156daf3ce87" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_7a94af52-eb34-4d21-9883-0dad4501fa80" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_498df01f-1e96-4185-85d8-a4f6dc46e2ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bea56bfb-a842-4237-9132-6b394d183820" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_498df01f-1e96-4185-85d8-a4f6dc46e2ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_137dcd7a-22c4-4a6b-a77b-6c8f680ba017" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_498df01f-1e96-4185-85d8-a4f6dc46e2ee" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_137dcd7a-22c4-4a6b-a77b-6c8f680ba017" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_147e4c7e-6a5a-4910-8157-c4657358ef9d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_498df01f-1e96-4185-85d8-a4f6dc46e2ee" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_147e4c7e-6a5a-4910-8157-c4657358ef9d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_60796a5c-b74b-4aa4-a003-fb3e145b3668" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_498df01f-1e96-4185-85d8-a4f6dc46e2ee" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_60796a5c-b74b-4aa4-a003-fb3e145b3668" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_efac2e33-f339-403f-9a42-d4f7fefa3bf7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/SharePlansPerformanceStockunitsDetails" xlink:type="simple" xlink:href="pnr-20231231.xsd#SharePlansPerformanceStockunitsDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/SharePlansPerformanceStockunitsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b89301bc-8b47-440d-8122-ab65f7330007" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1e256d55-99cf-4a42-b02a-8631e51e5005" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b89301bc-8b47-440d-8122-ab65f7330007" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1e256d55-99cf-4a42-b02a-8631e51e5005" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_acb82078-b5ce-47d6-8865-77b2dec87add" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1e256d55-99cf-4a42-b02a-8631e51e5005" xlink:to="loc_us-gaap_AwardTypeAxis_acb82078-b5ce-47d6-8865-77b2dec87add" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_acb82078-b5ce-47d6-8865-77b2dec87add_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_acb82078-b5ce-47d6-8865-77b2dec87add" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_acb82078-b5ce-47d6-8865-77b2dec87add_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_faf69ce4-09d9-4ed9-aace-a6c48321feb3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_acb82078-b5ce-47d6-8865-77b2dec87add" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_faf69ce4-09d9-4ed9-aace-a6c48321feb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_677987c7-a062-4c89-b8be-7fbc6bbb5626" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_faf69ce4-09d9-4ed9-aace-a6c48321feb3" xlink:to="loc_us-gaap_PerformanceSharesMember_677987c7-a062-4c89-b8be-7fbc6bbb5626" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_d0090353-7c20-47cd-b1fe-b06073b0823b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b89301bc-8b47-440d-8122-ab65f7330007" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_d0090353-7c20-47cd-b1fe-b06073b0823b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e243af5c-1faa-46d2-93a1-b58ee212e1ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b89301bc-8b47-440d-8122-ab65f7330007" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e243af5c-1faa-46d2-93a1-b58ee212e1ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_58d20831-4b36-4cbe-8cfe-7fff8118b94c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e243af5c-1faa-46d2-93a1-b58ee212e1ef" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_58d20831-4b36-4cbe-8cfe-7fff8118b94c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_9f72482f-6d59-4c8e-99ed-a219432b188e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e243af5c-1faa-46d2-93a1-b58ee212e1ef" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_9f72482f-6d59-4c8e-99ed-a219432b188e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_37e6b94a-18cc-411a-aafc-f6a2ac985d31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e243af5c-1faa-46d2-93a1-b58ee212e1ef" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_37e6b94a-18cc-411a-aafc-f6a2ac985d31" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_12df6d61-4757-42a8-9165-05a25ddac925" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_9e262c57-195b-444c-8641-c5b6bb57104b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b89301bc-8b47-440d-8122-ab65f7330007" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_9e262c57-195b-444c-8641-c5b6bb57104b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_6a3ec40c-feaa-497a-aa3d-f2c3ab1cda7f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_9e262c57-195b-444c-8641-c5b6bb57104b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_6a3ec40c-feaa-497a-aa3d-f2c3ab1cda7f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_957b9bf7-ecd3-4021-953e-269de8e580ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_9e262c57-195b-444c-8641-c5b6bb57104b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_957b9bf7-ecd3-4021-953e-269de8e580ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_42da12f9-1944-4cb9-805f-d91d25f4431f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_9e262c57-195b-444c-8641-c5b6bb57104b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_42da12f9-1944-4cb9-805f-d91d25f4431f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_c0d02707-5818-4b42-9785-3532aa24824d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/SegmentInformationFinancialInformationByReportableSegmentDetail" xlink:type="simple" xlink:href="pnr-20231231.xsd#SegmentInformationFinancialInformationByReportableSegmentDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/SegmentInformationFinancialInformationByReportableSegmentDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_009354b7-9e3f-4fd4-b599-d8f4282c0c3c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_2321e713-bf55-4d25-a807-42e706acfa90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_009354b7-9e3f-4fd4-b599-d8f4282c0c3c" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_2321e713-bf55-4d25-a807-42e706acfa90" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_9b6fbe9a-5853-4383-9031-3205d789e83b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_2321e713-bf55-4d25-a807-42e706acfa90" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_9b6fbe9a-5853-4383-9031-3205d789e83b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_9b6fbe9a-5853-4383-9031-3205d789e83b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_9b6fbe9a-5853-4383-9031-3205d789e83b" xlink:to="loc_us-gaap_SegmentDomain_9b6fbe9a-5853-4383-9031-3205d789e83b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_1aa2e386-0b40-4546-97ee-b85f0e0f0886" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_9b6fbe9a-5853-4383-9031-3205d789e83b" xlink:to="loc_us-gaap_SegmentDomain_1aa2e386-0b40-4546-97ee-b85f0e0f0886" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_FlowMember_44a81a2d-b925-454f-83e9-784a306d948f" xlink:href="pnr-20231231.xsd#pnr_FlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1aa2e386-0b40-4546-97ee-b85f0e0f0886" xlink:to="loc_pnr_FlowMember_44a81a2d-b925-454f-83e9-784a306d948f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_WaterSolutionsMember_c3eaeaef-83fe-4b0f-8dbf-ee2c2d2eb07b" xlink:href="pnr-20231231.xsd#pnr_WaterSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1aa2e386-0b40-4546-97ee-b85f0e0f0886" xlink:to="loc_pnr_WaterSolutionsMember_c3eaeaef-83fe-4b0f-8dbf-ee2c2d2eb07b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_PoolMember_b520675e-d2cf-4099-baaf-38510958f07e" xlink:href="pnr-20231231.xsd#pnr_PoolMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1aa2e386-0b40-4546-97ee-b85f0e0f0886" xlink:to="loc_pnr_PoolMember_b520675e-d2cf-4099-baaf-38510958f07e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateMember_181bbcc4-8839-48aa-8370-552aff071278" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1aa2e386-0b40-4546-97ee-b85f0e0f0886" xlink:to="loc_us-gaap_CorporateMember_181bbcc4-8839-48aa-8370-552aff071278" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_6accaf75-f22b-4e78-8b7c-9652edb87914" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_2321e713-bf55-4d25-a807-42e706acfa90" xlink:to="loc_srt_MajorCustomersAxis_6accaf75-f22b-4e78-8b7c-9652edb87914" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_6accaf75-f22b-4e78-8b7c-9652edb87914_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_6accaf75-f22b-4e78-8b7c-9652edb87914" xlink:to="loc_srt_NameOfMajorCustomerDomain_6accaf75-f22b-4e78-8b7c-9652edb87914_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_7a32e403-a91a-46f6-8aeb-d32512a36d0d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_6accaf75-f22b-4e78-8b7c-9652edb87914" xlink:to="loc_srt_NameOfMajorCustomerDomain_7a32e403-a91a-46f6-8aeb-d32512a36d0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_CustomerOneMember_f0cb0197-ad7c-492a-be9a-569ec4a3daa4" xlink:href="pnr-20231231.xsd#pnr_CustomerOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_7a32e403-a91a-46f6-8aeb-d32512a36d0d" xlink:to="loc_pnr_CustomerOneMember_f0cb0197-ad7c-492a-be9a-569ec4a3daa4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_e59e8cd1-5a93-487e-85c2-6b5131133d5f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_2321e713-bf55-4d25-a807-42e706acfa90" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_e59e8cd1-5a93-487e-85c2-6b5131133d5f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_e59e8cd1-5a93-487e-85c2-6b5131133d5f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_e59e8cd1-5a93-487e-85c2-6b5131133d5f" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_e59e8cd1-5a93-487e-85c2-6b5131133d5f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_9e94ab0c-25a9-43ff-9865-cb9a5cde56b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_e59e8cd1-5a93-487e-85c2-6b5131133d5f" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_9e94ab0c-25a9-43ff-9865-cb9a5cde56b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueNetMember_3a67fe52-0d1e-4710-9594-09946ca13584" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SalesRevenueNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_9e94ab0c-25a9-43ff-9865-cb9a5cde56b4" xlink:to="loc_us-gaap_SalesRevenueNetMember_3a67fe52-0d1e-4710-9594-09946ca13584" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_b61cc56c-f84b-43d9-b0b2-2a66ec2ee4a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_2321e713-bf55-4d25-a807-42e706acfa90" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_b61cc56c-f84b-43d9-b0b2-2a66ec2ee4a1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_b61cc56c-f84b-43d9-b0b2-2a66ec2ee4a1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_b61cc56c-f84b-43d9-b0b2-2a66ec2ee4a1" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_b61cc56c-f84b-43d9-b0b2-2a66ec2ee4a1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_24669508-c804-442e-b529-7e8df601bbde" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_b61cc56c-f84b-43d9-b0b2-2a66ec2ee4a1" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_24669508-c804-442e-b529-7e8df601bbde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_467913f3-4a39-4889-9f36-98ab520d6537" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_24669508-c804-442e-b529-7e8df601bbde" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_467913f3-4a39-4889-9f36-98ab520d6537" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_e3c6c48b-d7fa-446a-9781-6fab34dee2e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_009354b7-9e3f-4fd4-b599-d8f4282c0c3c" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_e3c6c48b-d7fa-446a-9781-6fab34dee2e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SegmentIncomeLoss_a33b4944-6aea-44d8-9a35-901aaa33c815" xlink:href="pnr-20231231.xsd#pnr_SegmentIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_009354b7-9e3f-4fd4-b599-d8f4282c0c3c" xlink:to="loc_pnr_SegmentIncomeLoss_a33b4944-6aea-44d8-9a35-901aaa33c815" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_faf29ddb-9bde-432c-baea-9be77fe8b817" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_009354b7-9e3f-4fd4-b599-d8f4282c0c3c" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_faf29ddb-9bde-432c-baea-9be77fe8b817" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_18e8675e-2dcd-4c28-9a54-d65c8f61ab29" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_009354b7-9e3f-4fd4-b599-d8f4282c0c3c" xlink:to="loc_us-gaap_Assets_18e8675e-2dcd-4c28-9a54-d65c8f61ab29" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_855a7299-f536-4bb9-bb69-1640f99677c6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentExpenditureAdditionToLongLivedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_009354b7-9e3f-4fd4-b599-d8f4282c0c3c" xlink:to="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_855a7299-f536-4bb9-bb69-1640f99677c6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_d6ff4b2b-04d0-4cd2-8473-c7979541d49b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_009354b7-9e3f-4fd4-b599-d8f4282c0c3c" xlink:to="loc_us-gaap_Depreciation_d6ff4b2b-04d0-4cd2-8473-c7979541d49b" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/SegmentInformationReconciliationofIncomefromContinuingOperationsfromSegmentstoConsolidatedDetails" xlink:type="simple" xlink:href="pnr-20231231.xsd#SegmentInformationReconciliationofIncomefromContinuingOperationsfromSegmentstoConsolidatedDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/SegmentInformationReconciliationofIncomefromContinuingOperationsfromSegmentstoConsolidatedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_32aa44aa-32dd-4ad7-bdb8-f1b2b60ea763" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_32aa44aa-32dd-4ad7-bdb8-f1b2b60ea763" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_5944e89d-3fc5-4edf-8782-21e4a3ddaac5" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_32aa44aa-32dd-4ad7-bdb8-f1b2b60ea763" xlink:to="loc_srt_ConsolidationItemsAxis_5944e89d-3fc5-4edf-8782-21e4a3ddaac5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_5944e89d-3fc5-4edf-8782-21e4a3ddaac5_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_5944e89d-3fc5-4edf-8782-21e4a3ddaac5" xlink:to="loc_srt_ConsolidationItemsDomain_5944e89d-3fc5-4edf-8782-21e4a3ddaac5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_6d9bfbca-086f-4e29-878d-f6671d623423" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_5944e89d-3fc5-4edf-8782-21e4a3ddaac5" xlink:to="loc_srt_ConsolidationItemsDomain_6d9bfbca-086f-4e29-878d-f6671d623423" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_ef679815-ae50-4635-bb84-76850ab5af6f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_6d9bfbca-086f-4e29-878d-f6671d623423" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_ef679815-ae50-4635-bb84-76850ab5af6f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SegmentIncomeLoss_1237a894-f827-46d9-bb5a-86f358e08803" xlink:href="pnr-20231231.xsd#pnr_SegmentIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_pnr_SegmentIncomeLoss_1237a894-f827-46d9-bb5a-86f358e08803" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_b8862234-e096-4d45-a6ae-08f88cc2d11f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_us-gaap_RestructuringCharges_b8862234-e096-4d45-a6ae-08f88cc2d11f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TransformationCosts_e839b4e9-4d4b-4dc6-b305-d9334131bd0a" xlink:href="pnr-20231231.xsd#pnr_TransformationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_pnr_TransformationCosts_e839b4e9-4d4b-4dc6-b305-d9334131bd0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_InventoryStepUpRelatedToMerger_788004bc-97ea-4d25-8230-028270571301" xlink:href="pnr-20231231.xsd#pnr_InventoryStepUpRelatedToMerger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_pnr_InventoryStepUpRelatedToMerger_788004bc-97ea-4d25-8230-028270571301" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPensionAndPostretirementObligations_17880789-8dd2-4aa2-9a14-122bf8289e57" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInPensionAndPostretirementObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_us-gaap_IncreaseDecreaseInPensionAndPostretirementObligations_17880789-8dd2-4aa2-9a14-122bf8289e57" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_c3af0880-3c0d-4b71-b205-a37c59413386" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_us-gaap_AssetImpairmentCharges_c3af0880-3c0d-4b71-b205-a37c59413386" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_5c798e66-bbc1-4a22-9414-e9e01ffa3329" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSaleOfBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_5c798e66-bbc1-4a22-9414-e9e01ffa3329" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessExitCosts1_4a49b6bd-7eca-4488-a141-80839639b954" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessExitCosts1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_us-gaap_BusinessExitCosts1_4a49b6bd-7eca-4488-a141-80839639b954" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_Dealrelatedcostsandexpenses_b7c66bad-e665-46ff-a4b1-39941ec3d3e3" xlink:href="pnr-20231231.xsd#pnr_Dealrelatedcostsandexpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_pnr_Dealrelatedcostsandexpenses_b7c66bad-e665-46ff-a4b1-39941ec3d3e3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_LegalSettlementAndAccrualAdjustments_5b13eead-9b45-4cbd-9455-7ddb23512cf0" xlink:href="pnr-20231231.xsd#pnr_LegalSettlementAndAccrualAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_pnr_LegalSettlementAndAccrualAdjustments_5b13eead-9b45-4cbd-9455-7ddb23512cf0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_9391dab1-5121-4c56-8639-afc0e98d00b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_9391dab1-5121-4c56-8639-afc0e98d00b9" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRevenueExpenseNet_3c313bf3-dade-4fb4-9d48-631eae411a80" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRevenueExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_us-gaap_InterestRevenueExpenseNet_3c313bf3-dade-4fb4-9d48-631eae411a80" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherExpenses_0a11fd58-b4e8-4b07-a067-c072c746b2f0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_us-gaap_OtherExpenses_0a11fd58-b4e8-4b07-a067-c072c746b2f0" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_d009862d-9536-466f-bbb3-147363edd651" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_df58392c-68ec-42be-94f2-1d83849bf5d7" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_d009862d-9536-466f-bbb3-147363edd651" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-roles-2023.xsd#eedm"/>
  <link:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsMiscellaneousNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsMiscellaneousNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_OtherAssetsMiscellaneousNoncurrent" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#AwardTypeOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockOptionMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_StockOptionMember" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_PerformanceSharesMember" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_RestrictedStockAndRestrictedStockUnitsRSUsMember_d36c1955-4ef6-4426-80c8-d50b6675164e" xlink:href="pnr-20231231.xsd#pnr_RestrictedStockAndRestrictedStockUnitsRSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_pnr_RestrictedStockAndRestrictedStockUnitsRSUsMember_d36c1955-4ef6-4426-80c8-d50b6675164e" xlink:type="arc" order="7"/>
  </link:definitionLink>
</link:linkbase>
