<SEC-DOCUMENT>0001179110-18-007851.txt : 20180601
<SEC-HEADER>0001179110-18-007851.hdr.sgml : 20180601
<ACCEPTANCE-DATETIME>20180601181903
ACCESSION NUMBER:		0001179110-18-007851
CONFORMED SUBMISSION TYPE:	5/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20171231
FILED AS OF DATE:		20180601
DATE AS OF CHANGE:		20180601

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BAKER DOUGLAS M JR
		CENTRAL INDEX KEY:			0001198753

	FILING VALUES:
		FORM TYPE:		5/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-09328
		FILM NUMBER:		18876338

	MAIL ADDRESS:	
		STREET 1:		370 WBASHA ST NORTH
		CITY:			ST PAUL
		STATE:			MN
		ZIP:			55102

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ECOLAB INC.
		CENTRAL INDEX KEY:			0000031462
		STANDARD INDUSTRIAL CLASSIFICATION:	SOAP, DETERGENT, CLEANING PREPARATIONS, PERFUMES, COSMETICS [2840]
		IRS NUMBER:				410231510
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1 ECOLAB PLACE
		CITY:			SAINT PAUL
		STATE:			MN
		ZIP:			55102
		BUSINESS PHONE:		18002326522

	MAIL ADDRESS:	
		STREET 1:		1 ECOLAB PLACE
		CITY:			SAINT PAUL
		STATE:			MN
		ZIP:			55102

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

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ECONOMICS LABORATORY INC
		DATE OF NAME CHANGE:	19861203
</SEC-HEADER>
<DOCUMENT>
<TYPE>5/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 5/A -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>5/A</documentType>

    <periodOfReport>2017-12-31</periodOfReport>

    <dateOfOriginalSubmission>2018-01-26</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <form3HoldingsReported>0</form3HoldingsReported>

    <form4TransactionsReported>0</form4TransactionsReported>

    <issuer>
        <issuerCik>0000031462</issuerCik>
        <issuerName>ECOLAB INC.</issuerName>
        <issuerTradingSymbol>ECL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001198753</rptOwnerCik>
            <rptOwnerName>BAKER DOUGLAS M JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 ECOLAB PLACE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAINT PAUL</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman and CEO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-12-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>11015</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>452432</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-12-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>6985</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7400</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Wife</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">On January 26, 2018, the reporting person filed a Form 5 to report a disposition of 18,000 shares of the issuer's common stock by a gift on December 8, 2017. The Form 5 inadvertently reported that all 18,000 shares were gifted from shares held by the reporting person in direct ownership form. In fact, as reported in this amendment, the gift was made from 11,015 shares held by the reporting person in direct ownership form and 6,985 shares held in indirect ownership form through his wife.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ David F. Duvick, Attorney-in-Fact for Douglas M. Baker, Jr.</signatureName>
        <signatureDate>2018-06-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
