X0306 4 2016-03-10 0000031462 ECOLAB INC. ECL 0000902012 GATES WILLIAM H III ONE MICROSOFT WAY REDMOND WA 98052 1 Common Stock 2016-03-10 4 P 0 457375.0000 105.4291 A 28377769.0000 I by Cascade Investment, L.L.C. Common Stock 2016-03-10 4 P 0 42624.0000 104.5927 A 28420393.0000 I by Cascade Investment, L.L.C. This transaction was executed in multiple trades at prices ranging from $104.9700 to $105.6400. The price set forth above reflects the weighted-average price per share. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transactions were effected. For purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, Mr. Gates, as the sole member of Cascade Investment, L.L.C. and co-trustee of Bill & Melinda Gates Foundation Trust ("Trust"), may be deemed to beneficially own more than 10% of the common stock of the Issuer. Mr. Gates has no pecuniary interest in the shares held by the Trust. Neither the filing of this Form 4 nor any of its contents shall be deemed an admission that Mr. Gates and any other person or persons constitute a "group" under Section 13(d) and Mr. Gates expressly disclaims membership in a group. This transaction was executed in multiple trades at prices ranging from $103.9650 to $104.9600. The price set forth above reflects the weighted-average price per share. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transactions were effected. /s/ Alan Heuberger, Attorney-in-fact for William H. Gates III 2016-03-14