How It Works

  • It starts with seawater used for cooling the Encina Power Station.
  • The seawater is treated with a pretreatment system to remove microscopic impurities.
  • Chemicals are added for further purification and the water is sent through a reverse osmosis (RO) system, a series of filtration membranes that removes the salt and any remaining impurities.
  • One of every two gallons of processed seawater becomes ultra high quality fresh water.
  • The other gallon is used to carry the salts removed in the RO process to the seawater discharged from the power plant as it returns to the ocean.
  • The Desalination Facility will be located adjacent to the Encina Power Station on a parcel currently occupied by a surplus tank.

When fully operational in late 2015, the Desalination Facility will have the capacity to deliver up to 50 million gallons per day (MGD) of reverse osmosis (RO) product water to the San Diego County Water Authority. The facilities include an intake pump station and pipeline, desalination plant, product water storage, concentrate discharge pipeline, wastestream treatment facilities and pipelines, transformers and substation, and a product water pump station.

Source water for the Project will come from the once-through non-contact seawater in the existing cooling water system at the Encina Power Station. Up to 104 MGD of seawater would be diverted from the combined outlet of the power station condensers and piped to the desalination facility. The source water will be pre-treated and filtered through RO membranes to produce high-quality drinking water.

The by-product of the RO treatment process is water with twice the salt content of seawater. This saline by-product will be diluted with the return flow from the power plant cooling water system prior to discharge to the Pacific Ocean.

The desalination facility will operate 24 hours a day, 7 days a week. This facility will produce water continuously and will be staffed at all times.

The pipeline route for transporting the desalinated water to the San Diego County Water Authority Aqueduct will exit the plant site on Avenida Encinas to Cannon Road to Faraday Avenue to Melrose Drive to Lionshead Avenue to Poinsettia Avenue to Linda Vista Drive to Las Flores Drive to 9th Street where it will connect to the Aqueduct.

Demonstration plant

A desalination pilot plant has been used since 2003 on-site to test the different desalination technologies available.