<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2014-10-24</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001324518</issuerCik>
        <issuerName>Williams Partners L.P.</issuerName>
        <issuerTradingSymbol>WPZ</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001483096</rptOwnerCik>
            <rptOwnerName>ACCESS MIDSTREAM PARTNERS LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>525 CENTRAL PARK DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>OKLAHOMA CITY</rptOwnerCity>
            <rptOwnerState>OK</rptOwnerState>
            <rptOwnerZipCode>73105</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>COMMON UNITS (LIMITED PARTNER INTERESTS)</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Access Midstream Partners, L.P. (&quot;ACMP&quot;) is deemed to have beneficial ownership over the 279,472,244 Common Units and 26,475,507 Class D Units of the Issuer held by Williams Gas Pipeline Company, LLC (&quot;WGP&quot;, and such held units, &quot;WGP Held Units&quot;), as a result of entering into that certain Support Agreement dated October 24, 2014, with WGP and the Issuer, pursuant to which, in part, WGP granted a proxy over the WGP Held Units to ACMP to vote in favor of, and otherwise agreed to consent to, the Merger and Merger Agreement (as defined below). (Continued in Footnote 2)</footnote>
        <footnote id="F2">On October 24, 2014, an Agreement and Plan of Merger (the &quot;Merger Agreement&quot;) was entered into among ACMP, its general partner-Access Midstream Partners GP, L.L.C.-, the Issuer, the Issuer's general partner-Williams Partners GP LLC-and VHMS LLC, a wholly owned subsidiary of ACMP (&quot;Merger Sub&quot;). Pursuant to the Merger Agreement, Merger Sub will be merged and into the Issuer, with the Issuer being the surviving partnership and ACMP becoming the sole limited partner of the Issuer (the &quot;Merger&quot;).</footnote>
        <footnote id="F3">ACMP does not have any pecuniary interest in any of the WGP Held Units and beneficial ownership over the WGP Held Units is expressly disclaimed.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ J. Mike Stice, Chief Executive Officer of Access Midstream Partners, L.P.</signatureName>
        <signatureDate>2014-10-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
