American Water Works Co., the biggest publicly traded water utility in the U.S., said its Pennsylvania unit today began work replacing more than 10 miles of aging water pipes in the Pittsburgh area.

Costs of the upgrades and network improvements that will improve pressure and boost fire protection for residents will be about $13.4 million, the company said in a statement. Some of the water mains are more than 100 years old, it said.

American Water is based in Voorhees, N.J., and its Pennsylvania subsidiary is the largest water utility in that state.

To contact the reporter on this story: Randall Hackley in London at rhackley@bloomberg.net

To contact the editor responsible for this story: Randall Hackley at rhackley@bloomberg.net