BIDDEFORD  The Biddeford and Saco Water Company announced Monday it has joined The Maine Water Company.

Both water companies became subsidiaries of Connecticut Water Service Inc. after regulatory approval was granted Nov. 7 by the Maine Public Utilities Commission.

The Biddeford and Saco Water Company was founded 131 years ago and serves 15,500 customers in Biddeford, Saco, Old Orchard Beach and Scarborough.

The Maine Water Company serves 16,000 customers across the state.

Jerry Mansfield, the retiring president of Biddeford and Saco Water, said joining the Maine Water family “begins a new chapter in our 131-year-old company.”

“Biddeford and Saco Water now will have added financial strength and access to resources to invest in infrastructure so the community can rely on a robust water system for health, public safety and economic development for years to come,” he said.

Judy Wallingford, president of Maine Water, also will serve as president of the Biddeford and Saco Water Company.

Rates will not increase as a result of the transaction, according to the companies. The Biddeford and Saco Water office on Elm Street in Biddeford will remain open.