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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 OdRzA1woUnRGd7H5+oZwc1ZHb3KtDzk7H02vUdjPsZLmbrBVQmzoNL1L18oZAJ4B
 1DRNmbfaQOYab84Vw8XtmQ==

<SEC-DOCUMENT>0000077360-08-000057.txt : 20080402
<SEC-HEADER>0000077360-08-000057.hdr.sgml : 20080402
<ACCEPTANCE-DATETIME>20080402132953
ACCESSION NUMBER:		0000077360-08-000057
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20080331
FILED AS OF DATE:		20080402
DATE AS OF CHANGE:		20080402

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

	MAIL ADDRESS:	
		STREET 1:		5500 WAYZATA BLVD.
		STREET 2:		SUITE 800
		CITY:			GOLDEN VALLEY
		STATE:			MN
		ZIP:			55416

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

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BORIN MARK C
		CENTRAL INDEX KEY:			0001430408

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-04689
		FILM NUMBER:		08732428

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		763-545-1730

	MAIL ADDRESS:	
		STREET 1:		5500 WAYZATA BOULEVARD
		STREET 2:		SUITE 800
		CITY:			GOLDEN VALLEY
		STATE:			MN
		ZIP:			55416
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2008-03-31</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000077360</issuerCik>
        <issuerName>PENTAIR INC</issuerName>
        <issuerTradingSymbol>PNR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001430408</rptOwnerCik>
            <rptOwnerName>BORIN MARK C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5500 WAYZATA BLVD.</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 800</rptOwnerStreet2>
            <rptOwnerCity>GOLDEN VALLEY</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55416-1261</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CAO, Controller</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <footnotes></footnotes>

    <ownerSignature>
        <signatureName>Louis L. Ainsworth, Attorney-In-Fact</signatureName>
        <signatureDate>2008-04-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>powerofattorney.txt
<DESCRIPTION>POWER OF ATTORNEY LETTER
<TEXT>
POWER OF ATTORNEY
       Know all by these presents that the undersigned hereby
constitutes and appoints Louis L. Ainsworth and John L. Stauch
and Angela D. Lageson, signing singly, the undersigned's
true and lawful attorneys-in-fact to:

(1)	execute for and on behalf of the undersigned, in the
undersigned's capacity as an officer and/or director of Pentair,
Inc. (the "Company"), Forms 3, 4, and 5 in accordance with
Section 16(a) of the Securities Exchange Act of 1934 and the
rules thereunder;

(2)	do and perform any and all acts for and on behalf of the
undersigned which may be necessary or desirable to complete and
execute any such Forms 3, 4, or 5 and timely file such form with
the United States Securities and Exchange Commission and any
stock exchange or similar authority; and

(3)	take any other action of any type whatsoever in connection
with the foregoing which, in the opinion of such attorneys-in-fact,
may be of benefit to, in the best interest of, or legally required
by, the undersigned, it being understood that the documents executed
by such attorneys-in-fact on behalf of the undersigned pursuant to
this power of attorney shall be in such form and shall contain such
terms and conditions as such attorneys-in-fact may approve in such
attorneys-in-fact's discretion.

       The undersigned hereby grants to such attorneys-in-fact
full power and authority to do and perform any and every act and
thing whatsoever requisite, necessary, or proper to be done in the
exercise of any of the rights and powers herein granted, as fully
to all intents and purposes as the undersigned might or could do if
personally present, with full power of substitution or revocation,
hereby ratifying and confirming all that such attorneys-in-fact, or
such attorneys-in-fact's substitute or substitutes, shall lawfully
do or cause to be done by virtue of this power of attorney and the
rights and powers herein granted. The undersigned acknowledges that
the foregoing attorneys-in-fact, in serving in such capacity at the
request of the undersigned, is not assuming, nor is the Company
assuming, any of the undersigned's responsibilities to comply with
Section 16 of the Securities Exchange Act of 1934.  The undersigned
accepts, through his or her signature, the responsibilities
conferred by the power of attorney.

       This power of attorney shall remain in full force and effect
until the undersigned is no longer required to file Forms 3, 4,
and 5 with respect to the undersigned's holdings of and transactions
in securities issued by the Company, unless earlier revoked by the
undersigned in a signed writing delivered to the foregoing
attorneys-in-fact.

       IN WITNESS WHEREOF, the undersigned has caused this power
of attorney to be executed as of this 19th day of March, 2008.


                                          Mark C. Borin
                                          Name of Reporting Person
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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