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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0000077360-04-000003.txt : 20040106
<SEC-HEADER>0000077360-04-000003.hdr.sgml : 20040106
<ACCEPTANCE-DATETIME>20040106160837
ACCESSION NUMBER:		0000077360-04-000003
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040102
FILED AS OF DATE:		20040106

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PENTAIR INC
		CENTRAL INDEX KEY:			0000077360
		STANDARD INDUSTRIAL CLASSIFICATION:	SPECIAL INDUSTRY MACHINERY (NO METALWORKING MACHINERY) [3550]
		IRS NUMBER:				410907434
		STATE OF INCORPORATION:			MN
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		5500 WAYZATA BLVD.
		STREET 2:		SUITE 800
		CITY:			GOLDEN VALLEY
		STATE:			MN
		ZIP:			55416
		BUSINESS PHONE:		763-545-1730

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	PENTAIR INDUSTRIES INC
		DATE OF NAME CHANGE:	19790327

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BROWN CHARLES M
		CENTRAL INDEX KEY:			0001258947

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-11625
		FILM NUMBER:		04510324

	BUSINESS ADDRESS:	
		STREET 1:		5500 WAYZATA BLVD
		STREET 2:		STE 800
		CITY:			GOLDEN VALLEY
		STATE:			MN
		ZIP:			55416
		BUSINESS PHONE:		7635451730
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>c0001258947d20040106f4f.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<ownershipDocument><schemaVersion>X0201</schemaVersion>    <documentType>4</documentType><periodOfReport>2004-01-02</periodOfReport><notSubjectToSection16>0</notSubjectToSection16><issuer><issuerCik>0000077360</issuerCik><issuerName>PENTAIR INC</issuerName>        <issuerTradingSymbol>PNR</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001258947</rptOwnerCik><rptOwnerName>BROWN CHARLES M</rptOwnerName></reportingOwnerId><reportingOwnerAddress><rptOwnerStreet1>5500 WAYZATA BLVD.</rptOwnerStreet1><rptOwnerStreet2>SUITE 800</rptOwnerStreet2><rptOwnerCity>GOLDEN VALLEY</rptOwnerCity><rptOwnerState>MN</rptOwnerState><rptOwnerZipCode>55416-1259</rptOwnerZipCode><rptOwnerStateDescription></rptOwnerStateDescription></reportingOwnerAddress><reportingOwnerRelationship><isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>President, COO Tools Group</officerTitle><otherText></otherText></reportingOwnerRelationship></repor
tingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2004-01-02</value></transactionDate><deemedExecutionDate></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F1"/></transactionCoding><transactionTimeliness><value></value></transactionTimeliness><transactionAmounts><transactionShares><value>8000</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>15000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></nonDerivative
Transaction></nonDerivativeTable><derivativeTable><derivativeTransaction><securityTitle><value>Employee Stock Option (right to buy)</value></securityTitle><conversionOrExercisePrice><value>45.76</value></conversionOrExercisePrice><transactionDate><value>2004-01-02</value></transactionDate><deemedExecutionDate></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F2"/></transactionCoding><transactionAmounts><transactionShares><value>35000</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2005-01-02</value><footnoteId id="F3"/></exerciseDate><expirationDate><value>2014-01-02</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares
><value>35000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>35000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">Restricted stock granted pursuant to the Pentair, Inc. Omnibus Stock Incentive Plan.  Shares remain subject to a vesting condition under the stock incentive plan.</footnote><footnote id="F2">Employee stock option granted pursuant to the Pentair, Inc. Omnibus Stock Incentive Plan.</footnote><footnote id="F3">One-third of the stock options become exercisable on the first, second, and third anniversary of the grant.</footnote></footnotes><ownerSignature><signatureName>Louis L. Ainsworth, Attorney-in-Fact</signatureName><signatureDate>2004-01-06</signatureDate></ownerSignature></owner
shipDocument>

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