Northborough sewer customers' bills due on Dec. 2 will include a 20 percent rate hike.
The water and sewer commission approved the increase, which affects about 4,200 customers, on Sept. 24 to "cover the cost" of running the department, according to a notice of utility rate adjustment. The notice will go out with the next bills, Public Works Director Dan Nason said Monday.
The board's decision came after an Aug. 27 public hearing on the proposal, according to the notice.
Northborough funds its water and sewer services through "self-supporting enterprise funds allowed under" state law, the notice states.
"Water and sewer rates must be adequate to finance each fund's operating and maintenance costs, debt service obligations and capital improvements," the notice states.
The commission also voted not to increase the water rates.