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    <submissionType>D</submissionType>

    <testOrLive>LIVE</testOrLive>

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        <entityName>NanoH2O, Inc.</entityName>
        <issuerAddress>
            <street1>750 LAIRPORT STREET</street1>
            <city>EL SEGUNDO</city>
            <stateOrCountry>CA</stateOrCountry>
            <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
            <zipCode>90245</zipCode>
        </issuerAddress>
        <issuerPhoneNumber>424 218-4000</issuerPhoneNumber>
        <jurisdictionOfInc>DELAWARE</jurisdictionOfInc>
        <issuerPreviousNameList>
            <value>None</value>
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        <edgarPreviousNameList>
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        <entityType>Corporation</entityType>
        <yearOfInc>
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            <value>2005</value>
        </yearOfInc>
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                <firstName>Jeffrey</firstName>
                <lastName>Green</lastName>
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                <street1>750 Lairport Street</street1>
                <city>El Segundo</city>
                <stateOrCountry>CA</stateOrCountry>
                <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
                <zipCode>90245</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Director</relationship>
                <relationship>Promoter</relationship>
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            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Gilad</firstName>
                <lastName>Almogy</lastName>
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                <street1>881 Northampton Drive</street1>
                <city>Palo Alto</city>
                <stateOrCountry>CA</stateOrCountry>
                <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
                <zipCode>94303</zipCode>
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            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
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            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Brian</firstName>
                <lastName>Hinman</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Oak Investment Partners, LP</street1>
                <street2>525 University Avenue, Suite 1300</street2>
                <city>Palo Alto</city>
                <stateOrCountry>CA</stateOrCountry>
                <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
                <zipCode>94301</zipCode>
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            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
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            <relationshipClarification></relationshipClarification>
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        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Samir</firstName>
                <lastName>Kaul</lastName>
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            <relatedPersonAddress>
                <street1>c/o Khosla Ventures</street1>
                <street2>3000 Sand Hill Road, Building 3, Suite 1</street2>
                <city>Menlo Park</city>
                <stateOrCountry>CA</stateOrCountry>
                <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
                <zipCode>90425</zipCode>
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                <relationship>Director</relationship>
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            <relatedPersonName>
                <firstName>James</firstName>
                <middleName>A.C.</middleName>
                <lastName>McDermott</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Rusheen Capital Partners, LLC</street1>
                <street2>2372 Mandeville Canyon Road</street2>
                <city>Los Angeles</city>
                <stateOrCountry>CA</stateOrCountry>
                <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
                <zipCode>90047</zipCode>
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                <relationship>Director</relationship>
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            <relationshipClarification></relationshipClarification>
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        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Robert</firstName>
                <lastName>Burk</lastName>
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            <relatedPersonAddress>
                <street1>750 Lairport Street</street1>
                <city>El Segundo</city>
                <stateOrCountry>CA</stateOrCountry>
                <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
                <zipCode>90245</zipCode>
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            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Promoter</relationship>
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        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>CJ</firstName>
                <lastName>Kurth</lastName>
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            <relatedPersonAddress>
                <street1>750 Lairport Street</street1>
                <city>El Segundo</city>
                <stateOrCountry>CA</stateOrCountry>
                <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
                <zipCode>90245</zipCode>
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            <relatedPersonRelationshipList>
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        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Jasandra</firstName>
                <lastName>Nyker</lastName>
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            <relatedPersonAddress>
                <street1>c/o PCG Clean Energy &amp; Technology Fund</street1>
                <street2>1200 Prospect Street, Suite 200</street2>
                <city>La Jolla</city>
                <stateOrCountry>CA</stateOrCountry>
                <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
                <zipCode>92037</zipCode>
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        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Michael</firstName>
                <lastName>DeMartino</lastName>
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            <relatedPersonAddress>
                <street1>750 Lairport Street</street1>
                <city>El Segundo</city>
                <stateOrCountry>CA</stateOrCountry>
                <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
                <zipCode>90245</zipCode>
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        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Nicholas</firstName>
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                <stateOrCountry>CA</stateOrCountry>
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                <zipCode>90245</zipCode>
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            <relatedPersonRelationshipList>
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            <relationshipClarification></relationshipClarification>
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        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>John</firstName>
                <lastName>Tomescu</lastName>
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            <relatedPersonAddress>
                <street1>750 Lairport Street</street1>
                <city>El Segundo</city>
                <stateOrCountry>CA</stateOrCountry>
                <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
                <zipCode>90245</zipCode>
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            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
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            <relationshipClarification></relationshipClarification>
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    <offeringData>
        <industryGroup>
            <industryGroupType>Environmental Services</industryGroupType>
        </industryGroup>
        <issuerSize>
            <revenueRange>No Revenues</revenueRange>
        </issuerSize>
        <federalExemptionsExclusions>
            <item>06</item>
        </federalExemptionsExclusions>
        <typeOfFiling>
            <newOrAmendment>
                <isAmendment>false</isAmendment>
            </newOrAmendment>
            <dateOfFirstSale>
                <value>2010-06-01</value>
            </dateOfFirstSale>
        </typeOfFiling>
        <durationOfOffering>
            <moreThanOneYear>false</moreThanOneYear>
        </durationOfOffering>
        <typesOfSecuritiesOffered>
            <isEquityType>true</isEquityType>
        </typesOfSecuritiesOffered>
        <businessCombinationTransaction>
            <isBusinessCombinationTransaction>false</isBusinessCombinationTransaction>
            <clarificationOfResponse></clarificationOfResponse>
        </businessCombinationTransaction>
        <minimumInvestmentAccepted>0</minimumInvestmentAccepted>
        <salesCompensationList></salesCompensationList>
        <offeringSalesAmounts>
            <totalOfferingAmount>49999997</totalOfferingAmount>
            <totalAmountSold>10000001</totalAmountSold>
            <totalRemaining>39999996</totalRemaining>
            <clarificationOfResponse></clarificationOfResponse>
        </offeringSalesAmounts>
        <investors>
            <hasNonAccreditedInvestors>false</hasNonAccreditedInvestors>
            <totalNumberAlreadyInvested>4</totalNumberAlreadyInvested>
        </investors>
        <salesCommissionsFindersFees>
            <salesCommissions>
                <dollarAmount>0</dollarAmount>
            </salesCommissions>
            <findersFees>
                <dollarAmount>0</dollarAmount>
            </findersFees>
            <clarificationOfResponse></clarificationOfResponse>
        </salesCommissionsFindersFees>
        <useOfProceeds>
            <grossProceedsUsed>
                <dollarAmount>0</dollarAmount>
            </grossProceedsUsed>
            <clarificationOfResponse></clarificationOfResponse>
        </useOfProceeds>
        <signatureBlock>
            <authorizedRepresentative>false</authorizedRepresentative>
            <signature>
                <issuerName>NanoH2O, Inc.</issuerName>
                <signatureName>Jeffrey Green</signatureName>
                <nameOfSigner>Jeffrey Green</nameOfSigner>
                <signatureTitle>Chief Executive Officer</signatureTitle>
                <signatureDate>2010-06-09</signatureDate>
            </signature>
        </signatureBlock>
    </offeringData>
</edgarSubmission>
