American Water Works (AWK) S-3ASR Automatic shelf registration

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form S-3 of our report dated February 28, 2012 relating to the financial statements and the effectiveness of internal control over financial reporting, which appears in American Water Works Company, Inc.’s Annual Report on Form 10-K for the year ended December 31, 2011. We also consent to the reference to us under the heading “Experts” in such Registration Statement.

/s/ PricewaterhouseCoopers LLP

Philadelphia, Pennsylvania

May 4, 2012