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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-08-02</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000276720</issuerCik>
        <issuerName>PURE CYCLE CORP</issuerName>
        <issuerTradingSymbol>PCYO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001409045</rptOwnerCik>
            <rptOwnerName>Epker Arthur G III</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O PURE CYCLE CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>8451 DELAWARE ST.</rptOwnerStreet2>
            <rptOwnerCity>THORNTON</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80260</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Non-Statutory Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>7.61</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-08-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-08-02</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Grant pursuant to the 2004 Incentive Plan approved by Pure Cycle's Stockholders.</footnote>
        <footnote id="F2">1/2 on 8/2/2008 and 1/2 on 8/2/2009.</footnote>
        <footnote id="F3">In addition to the options granted to Mr. Epker, 2,617,939 shares of common stock are held directly by PAR Investment Partners, L.P. (&quot;PIP&quot;). PAR Capital Management, Inc. (&quot;PCM&quot;), as the general partner of PAR Group, L.P., which is the general partner of PIP, has investment discretion and voting control over shares held by PIP. No stockholder, director, officer of employee of PCM has beneficial ownership (within the meaning of Rule 13d-3 promulgated under the Exchange Act) of any shares held by PIP. The shares held by PIP are part of a portfolio managed by Mr. Epker. As an employee of PCM, Mr. Epker has the authority to trade the securities held by PIP.</footnote>
    </footnotes>

    <remarks>Pursuant to a Power of Attorney filed as Exhibit 24 to a Form 3 filed with the Commission on August 8, 2007.</remarks>

    <ownerSignature>
        <signatureName>Arthur G. Epker III, by Mark W. Harding as Attorney-in-Fact (see Remarks)</signatureName>
        <signatureDate>2007-08-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
