The Washington Suburban Sanitary Commission wants to raise Prince George’s and Montgomery County residents’ water bills 7.5 percent, or an average of $4.86 per month, beginning in July.

The increase is the result of a $265.9 million, or 22.3 percent, increase in the agency’s budget for fiscal 2013. The vast majority of the hike — $230.9 million — would go toward a proposed $796.9 million construction budget.