Residents of Prince George's and Montgomery counties will see their rates for water use jump by 8 percent starting July 1, raising the average customer's quarterly bill by $11.25.

Meeting jointly, the councils of the two counties agreed to the increase yesterday as they approved a $913.7 million budget for the Washington Suburban Sanitary Commission, which provides water and sewer service to 1.8 million customers in the counties.

The budget will fund the utility's operations as well as the replacement of 27 miles of water lines and 51 miles of sewer pipes.

By state law, the utility's budget must be submitted for consideration to the Montgomery and Prince George's councils. The utility has six commissioners, who make up the governing body of the utility. The executives of the two counties each appoint three.

The commissioners agreed in February to an 8 percent increase after the members who represent the counties clashed over a proposal by the utility to raise rates by 9.5 percent. Utility managers also wanted to impose a monthly $20 fee devoted to replacing the system's 10,800 miles of underground water and sewer pipes. The managers said there is a desperate need to take action to prevent breaks.

With the 9.5 percent increase and the fee, water bills would have risen 50 percent starting in July. Commissioners rejected the fee in February.