How does the Islands sewer system work?
A sanitary sewer pipe, partially buried in Lake Washington five to ten feet offshore, surrounds Mercer Island. Sewage is transported by gravity from the upland elevations down to the lakeline. Once in the lakeline, sewage is conveyed around the Island by City-owned pump stations to two King County pump stations and from there, across Lake Washington to the regional sewage treatment plant in Renton.
