FREEPORT — The Maine Public Utilities Commission has approved a 9 percent rate increase for water system users in town, the commission announced today.

Effective Aug. 1, it’s the first rate increase since 2003 and applies to 960 customers in town, according to Aqua Maine, the public water utility that owns and operates the system.

“We continue to replace aging infrastructure throughout this system, and have made nearly $650,000 of capital improvements since the last time rates were increased,” said Judy Wallingford, president of Aqua Maine.

The increase doesn’t apply to 250 public water users in the village of South Freeport, which has a separate system that is operated but not owned by Aqua Maine.

With the increase, the average quarterly bill for a customer using 1,500 cubic feet of water will be $76.08, an increase of $7.77, according to Aqua Maine.

The commission also approved a reduction in the volume that qualifies for minimum base charges, from 1,200 to 300 cubic feet per quarter.

The commission’s review confirmed that the rate changes were necessary for Aqua Maine to continue providing “an adequately safe and reliable level of service to its customers,” said Tom Welch, commission chairman.

“It is always difficult for customers to bear increases in rates for essential services,” Welch said, adding that the increases may encourage water conservation and help reduce costs in the long run.

The water systems in Freeport and South Freeport are two of 20 systems in Maine that are owned or operated by Aqua Maine. It’s part of Aqua America, which provides water and wastewater services to more than 3 million customers in 12 states.

The commission approved similar increases for Aqua Maine in Skowhegan and Millinocket.