GWRS Final Expansion Spring Update

The Groundwater Replenishment System (GWRS) is the world’s largest potable water purification system, taking highly treated wastewater that would have previously been discharged into the Pacific Ocean and purifying it using a three-step advanced treatment process consisting of microfiltration, reverse osmosis, and ultraviolet light with hydrogen peroxide. The GWRS Final Expansion (GWRSFE) project will increase treatment capacity from 100 to 130 million gallons per day (MGD), which is enough water for 1 million people.

In order to produce 130 MGD, additional treated wastewater from the Orange County Sanitation District (OCSD) is required. This additional water will come from OCSD’s Treatment Plant 2, located in the city of Huntington Beach approximately 3.5 miles south of the GWRS. Current construction activities include the following:

Fountain Valley - Construction crews are expanding the footprint of the microfiltration treatment area by building additional treatment tanks and pipeline above and below ground. All construction activities are taking place within Orange County Water District (OCWD) grounds. However, large equipment may be visible from outside OCWD, and you may feel vibrations during shoring activities.

Huntington Beach - Two concrete tanks 30 feet high with a combined capacity of six million gallons, and a new pump station to move treated wastewater from the tanks to the GWRS in Fountain Valley are being constructed within the Orange County Sanitation District (OCSD) Plant II. The first phase involves grading and excavating the area. Increased truck traffic in and out of the facility may be noticeable for certain construction activities, such as deliveries and concrete pours.

For additional information about the GWRS or GWRSFE project, please visit For questions pertaining to construction at OCWD in Fountain Valley, please call (714) 378-8244. For questions pertaining to construction at OCSD in Huntington Beach, please call (714) 378-2965.