Exhibit 32.2

AMERICAN WATER WORKS COMPANY, INC.

CERTIFICATION

PURSUANT TO 18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the annual report of American Water Works Company, Inc. (the “Company”) on Form 10-K for the period ended December 31, 2008, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Ellen C. Wolf, Senior Vice President and Chief Financial Officer, of the Company, hereby certify pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

(1) The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 as amended; and

(2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

By:	/S/    ELLEN C. WOLF
	Ellen C. Wolf Senior Vice President and Chief Financial Officer (Principal Financial and Accounting Officer) February 27, 2009