<SEC-DOCUMENT>0001140361-12-044147.txt : 20121018
<SEC-HEADER>0001140361-12-044147.hdr.sgml : 20121018
<ACCEPTANCE-DATETIME>20121018191618
ACCESSION NUMBER:		0001140361-12-044147
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20121016
FILED AS OF DATE:		20121018
DATE AS OF CHANGE:		20121018

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BRYAN GLYNIS
		CENTRAL INDEX KEY:			0001270817

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-11625
		FILM NUMBER:		121151263

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

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PENTAIR LTD
		CENTRAL INDEX KEY:			0000077360
		STANDARD INDUSTRIAL CLASSIFICATION:	SPECIAL INDUSTRY MACHINERY (NO METALWORKING MACHINERY) [3550]
		IRS NUMBER:				981050812
		STATE OF INCORPORATION:			V8
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		FREIER PLATZ 10
		CITY:			SCHAFFHAUSEN
		STATE:			V8
		ZIP:			CH-8200
		BUSINESS PHONE:		763-545-1730

	MAIL ADDRESS:	
		STREET 1:		C/O PENTAIR MANAGEMENT COMPANY
		STREET 2:		5500 WAYZATA BLVD
		CITY:			GOLDEN VALLEY
		STATE:			MN
		ZIP:			55416

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	PENTAIR INC
		DATE OF NAME CHANGE:	19920703

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	PENTAIR INDUSTRIES INC
		DATE OF NAME CHANGE:	19790327
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-10-16</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001270817</rptOwnerCik>
            <rptOwnerName>BRYAN GLYNIS</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5500 WAYZATA BLVD., SUITE 800</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GOLDEN VALLEY</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55416</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2012-10-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8881</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14505</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock Units (Deferred Compensation)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2012-10-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8881.77</value>
                    <footnoteId id="F4"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8881.77</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4570.531</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Plan Agent</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Fractional shares were sold upon the settlement of units.</footnote>
        <footnote id="F2">Phantom stock units convert into common shares on a one-for-one basis.</footnote>
        <footnote id="F3">Includes 1,338 shares that were distributed in settlement of deferred share units.</footnote>
        <footnote id="F4">Represents phantom stock units credited under a deferred compensation plan for non-employee directors over which the reporting person has no current dispositive or voting power.</footnote>
        <footnote id="F5">A portion of the phantom stock units were settled in Pentair common shares on October 16, 2012.  Settlement of the remaining phantom stock units will be in Pentair common shares in accordance with reporting person's irrevocable election.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ John K. Wilson, Attorney-in-Fact for Glynis Bryan</signatureName>
        <signatureDate>2012-10-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
