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  <element name="FirstMortgage10Member" id="msex_FirstMortgage10Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage22Member" id="msex_FirstMortgage22Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage5Member" id="msex_FirstMortgage5Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="StateRevolvingTrustBond1Member" id="msex_StateRevolvingTrustBond1Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage16Member" id="msex_FirstMortgage16Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="StateRevolvingTrustNote8Member" id="msex_StateRevolvingTrustNote8Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PennsylvaniaPublicUtilitiesCommissioMember" id="msex_PennsylvaniaPublicUtilitiesCommissioMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="DeferredTaxAssetsCustomerAdvances" id="msex_DeferredTaxAssetsCustomerAdvances" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="debit"/>
  <element name="LeaseMaturityDate" id="msex_LeaseMaturityDate" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="MiddlesexWaterCompanyMember" id="msex_MiddlesexWaterCompanyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="SystemOfAccountsPolicyTextBlock" id="msex_SystemOfAccountsPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="TwinLakesMember" id="msex_TwinLakesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="RecentDevelopmentsPolicyTextBlock" id="msex_RecentDevelopmentsPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PurchaseCommitment2Member" id="msex_PurchaseCommitment2Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="CommercialOperatingRevenues" id="msex_CommercialOperatingRevenues" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="FirstMortgage13Member" id="msex_FirstMortgage13Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="SuperstormSandyRelatedCosts" id="msex_SuperstormSandyRelatedCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="PurchaseCommitment1Member" id="msex_PurchaseCommitment1Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PinelandsWastewaterMember" id="msex_PinelandsWastewaterMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="InitialPaymentReceivedFromInsuranceClaim" id="msex_InitialPaymentReceivedFromInsuranceClaim" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="FirstMortgage8Member" id="msex_FirstMortgage8Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="DeferredChargesAndOtherAssets" id="msex_DeferredChargesAndOtherAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="debit"/>
  <element name="ShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateValueUnearnedCompensation" id="msex_ShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateValueUnearnedCompensation" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="CommitmentAndContingenciesLineItems" id="msex_CommitmentAndContingenciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="AllowanceForFundsUsedDuringConstructionRatesTableTextBlock" id="msex_AllowanceForFundsUsedDuringConstructionRatesTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="InterimRates" id="msex_InterimRates" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="ProceedsFromPremiumIssuanceOfLongtermDebt" id="msex_ProceedsFromPremiumIssuanceOfLongtermDebt" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="OrganizationSummaryOfSignificantAccountingPoliciesAndRecentDevelopmentsAbstract" id="msex_OrganizationSummaryOfSignificantAccountingPoliciesAndRecentDevelopmentsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="VestedUnearnedCompensation" id="msex_VestedUnearnedCompensation" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="CommonStockInPlanValue" id="msex_CommonStockInPlanValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="ProjectedAnnualRevenue" id="msex_ProjectedAnnualRevenue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="SecuredDebt4Member" id="msex_SecuredDebt4Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="DeferredTaxLiabilitiesInvestmentTaxCredits" id="msex_DeferredTaxLiabilitiesInvestmentTaxCredits" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="PreliminarySurveyAndInvestigationCharges" id="msex_PreliminarySurveyAndInvestigationCharges" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="debit"/>
  <element name="StateRevolvingTrustBondMember" id="msex_StateRevolvingTrustBondMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="LowCommonStockPrice" id="msex_LowCommonStockPrice" type="num:perShareItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PreferredEquitySecuritiesMember" id="msex_PreferredEquitySecuritiesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="CashPaidDuringYearForAbstract" id="msex_CashPaidDuringYearForAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="ExpectedAmortizedActuarialLoss" id="msex_ExpectedAmortizedActuarialLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="MaximumAnnualRevenuesAllowedUnderFoundationalFiling" id="msex_MaximumAnnualRevenuesAllowedUnderFoundationalFiling" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="FirstMortgage20Member" id="msex_FirstMortgage20Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="NumberOfCustomers" id="msex_NumberOfCustomers" type="xbrli:integerItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="AdoptionOfRightOfUseAsset" id="msex_AdoptionOfRightOfUseAsset" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="OutsideDirectorStockCompensationPlanMember" id="msex_OutsideDirectorStockCompensationPlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="TDOtherMember" id="msex_TDOtherMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="BudgetedConstructionCostForConstructionProgramYearTwo" id="msex_BudgetedConstructionCostForConstructionProgramYearTwo" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="CostOfTreatedWater" id="msex_CostOfTreatedWater" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="ReserveAgainstTangiblePropertyDeductions" id="msex_ReserveAgainstTangiblePropertyDeductions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="EmployeeBenefits" id="msex_EmployeeBenefits" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="LoanAmountInitiallySetUpAsMarketbasedVariableInterestRateTransaction" id="msex_LoanAmountInitiallySetUpAsMarketbasedVariableInterestRateTransaction" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="PercentageOfCorporateTaxRegulatedCompainesPretax" id="msex_PercentageOfCorporateTaxRegulatedCompainesPretax" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage6Member" id="msex_FirstMortgage6Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="WeightedAverageAssumptionsAbstract" id="msex_WeightedAverageAssumptionsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="IncomeTaxesMember" id="msex_IncomeTaxesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="AmortizingSecuredNotesMember" id="msex_AmortizingSecuredNotesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="ReimbursementsReceivedForPreliminarySurveyAndInvestigationCosts" id="msex_ReimbursementsReceivedForPreliminarySurveyAndInvestigationCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="CompensationIncreaseForAbstract" id="msex_CompensationIncreaseForAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="UnearnedRevenuesAndAdvancedServiceFees" id="msex_UnearnedRevenuesAndAdvancedServiceFees" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="ReserveProvision" id="msex_ReserveProvision" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="AllocationOfPlanAssetsTableTextBlock" id="msex_AllocationOfPlanAssetsTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="SecuredDebt5Member" id="msex_SecuredDebt5Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PercentageOfPrincipalWithBondInterestRate" id="msex_PercentageOfPrincipalWithBondInterestRate" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="ImputedInterest" id="msex_ImputedInterest" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="debit"/>
  <element name="IncomeTaxReconciliationTangiblePropertyRepairs" id="msex_IncomeTaxReconciliationTangiblePropertyRepairs" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="EstimatedObligationExpend" id="msex_EstimatedObligationExpend" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="FirstMortgage4Member" id="msex_FirstMortgage4Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PercentOfParticipantsContributionsMatchedByCompanyBelowOnePercentOfParticipantsCompensation" id="msex_PercentOfParticipantsContributionsMatchedByCompanyBelowOnePercentOfParticipantsCompensation" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="InterSegmentEliminationOperatingRevenues" id="msex_InterSegmentEliminationOperatingRevenues" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="FirstMortgage23Member" id="msex_FirstMortgage23Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="StateRevolvingTrustNote6Member" id="msex_StateRevolvingTrustNote6Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgagesSixMember" id="msex_FirstMortgagesSixMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="NewJerseyEconomicDevelopmentAuthorityMember" id="msex_NewJerseyEconomicDevelopmentAuthorityMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage27Member" id="msex_FirstMortgage27Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="TaxEffectOfAbstract" id="msex_TaxEffectOfAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage9Member" id="msex_FirstMortgage9Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PercentageOfOfferingSharesOnDiscountToParticipants" id="msex_PercentageOfOfferingSharesOnDiscountToParticipants" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="CustomersAdvancesForConstructionCacPolicyTextBlock" id="msex_CustomersAdvancesForConstructionCacPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="ThresholdPercentageOfParticipantsCompensationAtWhichMatchingDecreases" id="msex_ThresholdPercentageOfParticipantsCompensationAtWhichMatchingDecreases" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="IncreaseDecreaseInAnnualRatePerCapitaCostOfCoveredHealthcareBenefitsYearsFourAndFive" id="msex_IncreaseDecreaseInAnnualRatePerCapitaCostOfCoveredHealthcareBenefitsYearsFourAndFive" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="StateRevolvingTrustNote11Member" id="msex_StateRevolvingTrustNote11Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="NewConstructionLoansMember" id="msex_NewConstructionLoansMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage24Member" id="msex_FirstMortgage24Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="SourceOfSupplyMember" id="msex_SourceOfSupplyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="DividendReinvestmenPlanSharesIssuedCumulative" id="msex_DividendReinvestmenPlanSharesIssuedCumulative" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage1Member" id="msex_FirstMortgage1Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="ConstructionAdvances" id="msex_ConstructionAdvances" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="AdditionalSharesAuthorizedBySECToBeIssued" id="msex_AdditionalSharesAuthorizedBySECToBeIssued" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant"/>
  <element name="RightOfUseAssetsCurrent" id="msex_RightOfUseAssetsCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="debit"/>
  <element name="PreliminarySurveyAndInvestigationPsiCostsPolicyTextBlock" id="msex_PreliminarySurveyAndInvestigationPsiCostsPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="StateRevolvingTrustNote2Member" id="msex_StateRevolvingTrustNote2Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="StateRevolvingTrustNote9Member" id="msex_StateRevolvingTrustNote9Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="NewJerseyInfrastructureBankThreeMember" id="msex_NewJerseyInfrastructureBankThreeMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="HighCommonStockPrice" id="msex_HighCommonStockPrice" type="num:perShareItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PercentOfOperatingRevenues" id="msex_PercentOfOperatingRevenues" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="IndustrialOperatingRevenues" id="msex_IndustrialOperatingRevenues" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="StateRevolvingTrustNote5Member" id="msex_StateRevolvingTrustNote5Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage30Member" id="msex_FirstMortgage30Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage12Member" id="msex_FirstMortgage12Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="NonregualtedContractOperationsRevenue" id="msex_NonregualtedContractOperationsRevenue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="AmountOfDrawnExpectedRemaining" id="msex_AmountOfDrawnExpectedRemaining" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="PercentageOfPrincipalWithStatedInterestRate" id="msex_PercentageOfPrincipalWithStatedInterestRate" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="ExpectedAmortizedPriorServiceCredit" id="msex_ExpectedAmortizedPriorServiceCredit" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="PreferredStockConvertibleConversionPrice" id="msex_PreferredStockConvertibleConversionPrice" type="num:perShareItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PercentOfTotalAssets" id="msex_PercentOfTotalAssets" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgagesFiveMember" id="msex_FirstMortgagesFiveMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="OriginallyFiledBaseWaterRateIncrease" id="msex_OriginallyFiledBaseWaterRateIncrease" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="FirstMortgage32Member" id="msex_FirstMortgage32Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="ReclassificationOfUnamortizedDebtExpenseDueToNewAccountingStandard" id="msex_ReclassificationOfUnamortizedDebtExpenseDueToNewAccountingStandard" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="EntityClosingMarketPricePerShare" id="msex_EntityClosingMarketPricePerShare" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant"/>
  <element name="BudgetedConstructionCostForConstructionProgramYearOne" id="msex_BudgetedConstructionCostForConstructionProgramYearOne" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="DividendReinvestmentCommonStockPurchasePlanMember" id="msex_DividendReinvestmentCommonStockPurchasePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="OrganizationSummaryOfSignificantAccountingPoliciesAndRecentDevelopmentsLineItems" id="msex_OrganizationSummaryOfSignificantAccountingPoliciesAndRecentDevelopmentsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage18Member" id="msex_FirstMortgage18Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="OperationsAndMaintenanceExpenseAndOtherIncomeExpenseNet" id="msex_OperationsAndMaintenanceExpenseAndOtherIncomeExpenseNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="SecuredDebt7April2Member" id="msex_SecuredDebt7April2Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage28Member" id="msex_FirstMortgage28Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="AmountsExpectedToBeAmortizedFromRegulatoryAssetsTableTextBlock" id="msex_AmountsExpectedToBeAmortizedFromRegulatoryAssetsTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="StateRevolvingTrustNoteMember" id="msex_StateRevolvingTrustNoteMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="ConstructionLoanMember" id="msex_ConstructionLoanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PercentageOfConsumerPriceIndex" id="msex_PercentageOfConsumerPriceIndex" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="EstimatedIncrementalBorrowingRate" id="msex_EstimatedIncrementalBorrowingRate" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant"/>
  <element name="TariffRateToRecoverAdditionalAnnualCosts" id="msex_TariffRateToRecoverAdditionalAnnualCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="ResidentialCommercialIndustrialAndFireProtectionRevenue" id="msex_ResidentialCommercialIndustrialAndFireProtectionRevenue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="FirstMortgage2Member" id="msex_FirstMortgage2Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgageBondsFairValueDisclosure" id="msex_FirstMortgageBondsFairValueDisclosure" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="DeferredAbstract" id="msex_DeferredAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="RateBase" id="msex_RateBase" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="CostOfPurchasedWaterAbstract" id="msex_CostOfPurchasedWaterAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="StateRevolvingNotesFairValueDisclosure" id="msex_StateRevolvingNotesFairValueDisclosure" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="AmortizationOfCompensationExpenseUnearnedCompensation" id="msex_AmortizationOfCompensationExpenseUnearnedCompensation" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="ChangeInFairValueOfPlanAssetsAbstract" id="msex_ChangeInFairValueOfPlanAssetsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage29Member" id="msex_FirstMortgage29Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="DeferredTaxLiabilitiesUtilityPlantRelated" id="msex_DeferredTaxLiabilitiesUtilityPlantRelated" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="TotalCommonEquity" id="msex_TotalCommonEquity" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="DiscountRateForAbstract" id="msex_DiscountRateForAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="ConvertibleDollar8PreferredSeriesStockDividends" id="msex_ConvertibleDollar8PreferredSeriesStockDividends" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="FirstMortgage17Member" id="msex_FirstMortgage17Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="TidewaterUtilitiesIncMember" id="msex_TidewaterUtilitiesIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="BaseRateAmount" id="msex_BaseRateAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="credit"/>
  <element name="EscrowAccountMaintainedFor2008RestrictedStockPlan" id="msex_EscrowAccountMaintainedFor2008RestrictedStockPlan" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PinelandsCompanyMember" id="msex_PinelandsCompanyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="RightOfUseAssetAtLeaseInception" id="msex_RightOfUseAssetAtLeaseInception" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="debit"/>
  <element name="PercentageOfStockThatMayBeRedeemedInGivenCalanderYear" id="msex_PercentageOfStockThatMayBeRedeemedInGivenCalanderYear" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant"/>
  <element name="SecuredDebt1Member" id="msex_SecuredDebt1Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="ConvertiblePreferredStockSeries8Member" id="msex_ConvertiblePreferredStockSeries8Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PercentOfParticipantsContributionsMatchedByCompanyAboveOnePercentOfParticipantsCompensation" id="msex_PercentOfParticipantsContributionsMatchedByCompanyAboveOnePercentOfParticipantsCompensation" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="TDServicesMember" id="msex_TDServicesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PercentageOfPrincipalWithMarketInterestRate" id="msex_PercentageOfPrincipalWithMarketInterestRate" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="ConvertiblePreferredStockSeries7Member" id="msex_ConvertiblePreferredStockSeries7Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage11Member" id="msex_FirstMortgage11Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="UnearnedCompensationAbstract" id="msex_UnearnedCompensationAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="OtherLoanSourceMaximumBorrowingCapacity" id="msex_OtherLoanSourceMaximumBorrowingCapacity" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="DecreaseInPensionAndOtherPostretirementDefinedBenefitPlansLiabilities" id="msex_DecreaseInPensionAndOtherPostretirementDefinedBenefitPlansLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="instant" xbrli:balance="credit"/>
  <element name="CurrentAbstract" id="msex_CurrentAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="IncrementalCommonSharesAttributableToConversionOfDollar7PreferredSeriesStock" id="msex_IncrementalCommonSharesAttributableToConversionOfDollar7PreferredSeriesStock" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="WastewaterCollectionMember" id="msex_WastewaterCollectionMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage31Member" id="msex_FirstMortgage31Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="PumpingMember" id="msex_PumpingMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="FirstMortgage21Member" id="msex_FirstMortgage21Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="IncreaseInBaseRatesRevenuePerYearPercent" id="msex_IncreaseInBaseRatesRevenuePerYearPercent" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="OrganizationSummaryOfSignificantAccountingPoliciesAndRecentDevelopmentsTable" id="msex_OrganizationSummaryOfSignificantAccountingPoliciesAndRecentDevelopmentsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" abstract="true" nillable="true" xbrli:periodType="duration"/>
  <element name="TermOfAgreement" id="msex_TermOfAgreement" type="xbrli:durationItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
  <element name="DeobligatedPrincipalPayments" id="msex_DeobligatedPrincipalPayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" xbrli:balance="debit"/>
  <element name="NewJerseyInfrastructureBankMember" id="msex_NewJerseyInfrastructureBankMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration"/>
</schema>
