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

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2006-11-29</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000811271</issuerCik>
        <issuerName>WORLDWATER &amp; POWER CORP</issuerName>
        <issuerTradingSymbol>WWAT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000808326</rptOwnerCik>
            <rptOwnerName>EMCORE CORP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>145 BELMONT DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>SOMERSET</rptOwnerStreet2>
            <rptOwnerCity>NEW JERSEY</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>08873</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Series D Preferred Convertible Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>.276</value>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>48928570</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Warrants to purchase Series D Preferred Convertible Stock</value>
                <footnoteId id="F3"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>.317</value>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2006-11-29</value>
            </exerciseDate>
            <expirationDate>
                <value>2016-11-29</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5050440</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The Series D Preferred Convertible Stock is convertible at any time, at the holder's election, and has no expiration date.</footnote>
        <footnote id="F2">Subject to adjustment as set forth in the Certificate of Designation.</footnote>
        <footnote id="F3">The Warrants may be exercised for 505,044 shares of Series D Preferred Convertible Stock, which is convertible into 5,050,440 shares of common stock</footnote>
        <footnote id="F4">Subject to adjustment as provided in the Warrant.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Howard W. Brodie</signatureName>
        <signatureDate>2006-12-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
