• Email
  • Print

Water Pollution Control Plant

The Donald M. Somers Water Pollution Control Plant is an advanced wastewater treatment facility where wastewater from residences and businesses in Sunnyvale flows for treatment before being discharged to the San Francisco Bay. The water is processed to standards set by the San Francisco Regional Water Quality Control Board.

Improvement Program

Originally constructed in 1956, the Plant is one of the oldest wastewater treatment facilities on the West Coast. In 2014, the City began construction on upgrades that are part of a 20-year improvement program to bring much-needed repairs to the Plant and accommodate new regulations and technology.

Stay up-to-date on Program Progress

Sunnyvale Cleanwater Program

Learn About the Plant's History

Timeline and Overview


The Water Pollution Control Plant:

  • Occupies 16.6 acres at 1444 Borregas Ave. and maintains 440 acres of treatment ponds (oxidation ponds).
  • Uses a unique controlled-ponding system in its treatment process.
  • Produces an average of 0.8 million gallons of recycled water per day for more than 100 customers under the Recycled Water Program.
  • Produces more than 2,500 dry tons of nutrient-rich "biosolids" in a typical year, the majority of which are applied to agricultural fields as fertilizer.
  • Utilizes "biogas" (methane) produced in its anaerobic digesters and the adjacent landfill to satisfy the majority of its operational energy demands.

The Plant Process

The Plant is a three-step (tertiary) treatment facility that removes pollutants from wastewater to make it clean enough to safely discharge into San Francisco Bay or recycle for non-potable uses. The Plant produces and delivers about 300 million gallons of recycled water per year.

Last Updated: Jul 9, 2021