King County Monthly Sewer Rates King County Wastewater charges a monthly fee for providing wastewater treatment. King County's monthly wastewater fee is billed to the District. In turn, the District passes this fee to the residences, businesses and industries connected to our wastewater collection system to recover the county charge. That amount is based on King County's monthly sewer rate and the number of customers served by the District. The King County wastewater treatment fees and charges are calculated on the same formulas for all customers whether in water/sewer districts, cities or unincorporated King County. No cost distinction is made between utility providers.
King County Sewer Treatment Capacity Charge Since 1990, King County has levied a capacity charge on new connections to the sewer system, which these new customers pay in addition to their monthly sewer bill. The capacity charge helps King County cover the cost of sewer improvement and expansion projects needed to serve new growth. Newly connecting customers are directly billed by King County for the capacity charge.