Soscol Water Recycling Facility

The Soscol Water Recycling Facility (SWRF) is a state-of-the-art wastewater treatment plant that utilizes many complex processes to produce treated wastewater and recycled water. Wastewater undergoes primary, secondary, and tertiary treatment and disinfection before being released to the Napa River or distributed for irrigation as recycled water.

Suscol Water Recycling Facility

At a Glance

  • Biosolids produced: 1,200 dry tons annually
  • Dry Weather Treatment Capacity: 15.4 million gallons per day
  • Energy produced: 2,975 megawatt hours annually (36% of energy used by the water recycling facility)
  • Hours of operation: 24 hours a day, 365 days a year
  • Methane gas produced: 150,000 cubic feet daily
  • Recycled Water Produced Annually: 650 million gallons annually


Wastewater that enters the treatment plant (influent) is about 99% water and 1% solids. The wastewater flows through a series of treatment processes that screens out large solids, removes smaller solids that sink or float, and then removes smaller materials that are dissolved in the wastewater. This treatment process involves physical, chemical, and biological treatment techniques.

Discharged Wastewater

NapaSan is permitted to discharge treated wastewater to the Napa River from October 1 through June 30.  An average of 12 million gallons per day of treated wastewater is discharged to the Napa River during these months. The rest of the water received by NapaSan during this time period is stored in our treatment ponds or treated and beneficially reused (recycled) for irrigation of landscaping, parks, golf courses, cemeteries, pasture lands, and vineyards.  From July 1 through September 30, discharge to the Napa River is prohibited by NapaSan’s water quality permit and wastewater is either stored in the treatment ponds or treated and beneficially reused for irrigation.  


Interested in a tour of our facility?  Learn about our tour schedule or take our virtual treatment plant tour by clicking here. To schedule an on-site tour of our treatment plant, call 707-258-6002.