These local agencies own and operate independent collection systems, which include pipelines and pump stations to collect and carry wastewater flows in their service area to King County's regional system for treatment and disposal. The local agencies have 30-year agreements with King County for this service. King County owns and operates the regional treatment plants, pipelines, pump stations, and other related facilities.

The county does not bill individual property owners for sewer service. Instead, it charges the local agencies an amount that is based on the county's monthly rate and the number of customers the agency serves. In turn, the local agencies bill their customers to recover the county charge plus the amount needed to operate and maintain their collection systems.

Local sewer agencies served by King County Wastewater Treatment Division