Residents and businesses in Montgomery and Prince George’s counties will pay 5.5 percent more for water and sewer service starting July 1 under a utility rate increase approved by both county councils Thursday.

The increase affects customers of the Washington Suburban Sanitary Commission (WSSC), which provides water and sewer service for nearly 2 million people in the Maryland suburbs.

Under the rate increase, a customer who uses 210 gallons of water daily would pay about $4 more per month, WSSC officials said. The increase, which comes after WSSC rates have soared 50 percent over the past six years, is the lowest since 2007, officials said.

WSSC officials say the $1.3 billion operating and capital budget for fiscal 2015 will focus on financing water and sewer pipe reconstruction and repairing other aging infrastructure. That includes funding to inspect, repair and replace large valves.

A broken 48-year-old valve led WSSC officials last summer to declare a water emergency for a large swath of Prince George’s County during a heat wave. Businesses closed and residents scrambled for water for two days before the valve was fixed in time to prevent an outage.

The WSSC’s six-member board of commissioners is expected to formally adopt the budget, including the rate increase, May 21.

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