UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 8-K

Current Report

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): January 17, 2012

American Water Works Company, Inc.

(Exact name of registrant as specified in its charter)

Commission File Number: 001-34028

1025 Laurel Oak Road

Voorhees, NJ 08043

(Address of principal executive offices, including zip code)

(856) 346-8200

(Registrant’s telephone number, including area code)

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Item 2.02. Results of Operations and Financial Condition

On January 17, 2012, American Water Works Company, Inc. (the “Company”) issued a press release announcing its earnings guidance estimate for 2012, and its expected 2011 earnings range. A copy of the press release is furnished as Exhibit 99.1 to this report and is incorporated by reference herein.

The Company has also furnished as Exhibit 99.2 to this report and incorporated by reference herein a copy of the slide presentation it will be providing to investors in connection with the conference call that Jeffry E. Sterba, President and Chief Executive Office and other representatives from the Company have scheduled with investors. The conference call will be webcast at 9:00 a.m., EST, on January 18, 2011 and available in the investor relations section of the Company’s web site at www.amwater.com.

Cautionary Statement Concerning Forward-Looking Statements

The earnings guidance set forth in this report constitutes a forward-looking statement within the meaning of the safe harbor provisions of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These forward-looking statements are predictions based on our current expectations and assumptions regarding our 2012 financial performance, including earnings. Actual results could differ materially because of factors such as the decisions of governmental and regulatory bodies, including decisions to raise or lower rates; the timeliness of regulatory commissions’ actions concerning rates; changes in laws, governmental regulations and policies, including environmental, health and water quality and public utility regulations and policies; weather conditions, patterns or events, including drought or abnormally high rainfall; changes in customer demand for, and patterns of use of, water, such as may result from conservation efforts; our ability to appropriately maintain current infrastructure and manage the expansion of our business; our ability to obtain permits for projects; changes in our capital requirements; our ability to control operating expenses and to achieve efficiencies in our operations; our ability to obtain adequate and cost-effective supplies of chemicals, electricity, fuel, water and other raw materials that are required for our operations; our ability to acquire successfully and integrate water and wastewater systems that are complementary to our operations and the growth of our business; cost overruns relating to improvements or the expansion of our operations; changes in general economic, business and financial market conditions; significant changes to our business processes and corresponding technology; access to sufficient capital on satisfactory terms; fluctuations in interest rates; restrictive covenants in or changes to the credit ratings on our current or future debt that could increase our financing costs or affect our ability to borrow, make payments on debt or pay dividends; fluctuations in the value of benefit plan assets and liabilities that could increase our cost and funding requirements; the incurrence of impairment charges; migration of customers into or out of our service territories; difficulty in obtaining insurance at acceptable rates and on acceptable terms and conditions; ability to retain and attract qualified employees; and civil disturbance, labor strikes or terrorist threats or acts or public apprehension about future disturbances or terrorist threats or acts.

For further information regarding risks and uncertainties associated with American Water’s business, please refer to American Water’s annual, quarterly and periodic SEC filings. Except as explicitly set forth in this report, the Company undertakes no duty to update the forward-looking statement contained in this report.

The information in this Current Report, including Exhibits 99.1 and 99.2, shall not be deemed “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 and shall not be incorporated into any registration statement or other document filed pursuant to the Securities Act of 1933, except as shall be expressly set forth by specific reference in such filing.

Signature(s)

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.