Company: AWK
Filing Date: 2025-02-27
Form Type: S-3ASR
Source: 0001410636-25-000050
Chunk: 1

Company: American Water Works Company, Inc.
Filing Date: 2025-02-27
Form: S-3ASR
Chunk 1
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 or interest reinvestment plans, check the following box. ý

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ¨

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ¨

If this Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. ý

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

| Large accelerated filer |     | ý |     | Accelerated filer         | ¨ |
| Non-accelerated filer   |     | ¨ |     | Smaller reporting company | ¨ |
|                         |     |   |     | Emerging growth company   | ¨ |

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ¨

### AMERICAN WATER STOCK DIRECT

#### 4,214,534 Shares
<div align='center'>A dividend reinvestment and direct stock purchase plan for American Water common stock</div>

American Water Works Company, Inc. (“American Water”) is pleased to offer U.S. citizens the opportunity to participate in American Water Stock Direct, a dividend reinvestment and direct stock purchase plan.

American Water Stock Direct offers you the opportunity to:

• Buy shares of American Water common stock conveniently and economically, even