Exhibit

We hereby consent to the incorporation by reference in the Registration Statements on Form S-8 (Nos. 333-219682, 333-217975, 333-168543 and 333-150381) and Form S-3 (Nos. 333-203949 and 333-209933) of American Water Works Company, Inc. of our report dated February 20, 2018 relating to the financial statements and the effectiveness of internal control over financial reporting, which appears in this Form 10‑K.