The Sanitary Sewer Utility operates and maintains the City's sewer collection lines and pump stations.

King County Sewer Project in Black Diamond
Growth in Black Diamond is projected to reach approximately 20,000 residents by 2025. As the City's wastewater conveyance and treatment provider, King County must build additional wastewater capacity in Black Diamond to accommodate the projected growth. To learn more about the King County project, please click here to go directly to the King County site.

Sewer (effective January 1, 2010)
Sewer rate is based on charges from King County Metro, Soos Creek Water & Sewer District, and Black Diamond Sewer plus water consumption.

Monthly charge
King County Metro $31.90
Soos Creek Water & Sewer District $ 3.87
Black Diamond Sewer $15.29
Total $51.06

For each additional commercial users, multi-family residences and mobile home parks served by the same water meter, there will be a charge of $10.00 per unit.
Water consumed in excess of 750 cubic feet per month, a rate of $4.27 per one hundred cubic feet will be charged.

The City has hired PacWest Engineering to update the Sewer Comprehensive Plan

The City of Black Diamond is working on new Development Standards.