Officials Dedicate Final Expansion of O.C.’s Groundwater Replenishment System

The county celebrates the completion of the world’s largest indirect potable water reuse facility.
Courtesy of OCWD

Today, the Orange County Water District (OCWD) and the Orange County Sanitation District (OC San) celebrated the completion of the Groundwater Replenishment System (GWRS), the world’s largest indirect potable reuse facility. 

The project is a remarkable milestone, as it has enabled the recycling of 100 percent of OC San’s reclaimable wastewater flows, providing up to 130 million gallons of water daily, enough to serve one million people. Operational since January 2008, the GWRS has produced more than 400 billion gallons of water and counting.

The GWRS utilizes a three-step advanced treatment process consisting of microfiltration, reverse osmosis, and ultraviolet light with hydrogen peroxide, to purify highly treated wastewater that would otherwise be discharged into the ocean. The resulting high-quality water is then pumped to recharge basins, where it naturally percolates into the Orange County Groundwater Basin and becomes part of the drinking water supply for 2.5 million people in north and central Orange County. GWRS water is also sent to injection wells located along Orange County’s coast to create a seawater intrusion barrier that protects groundwater supplies.

“The GWRS is a premier example of vision, innovation, and collaborationall of which are key components of the project’s successes over the years, further cementing our pioneering role in water reuse,” says OCWD board president Cathy Green, who acted as master of ceremonies at the dedication. 

Lawmakers in attendance included U.S. representatives Lou Correa, Young Kim, and Katie Porter, California senator Dave Min, and California assembly members Cottie Petrie-Norris, Tri Ta, and Diane Dixon. U.S. senator Alex Padilla also appeared in a video message to celebrate the achievement.

The project reduces the volume of treated wastewater discharged into the ocean, improves water quality in the basin, and offers a more cost-effective and energy-efficient alternative than importing water from northern California or the Colorado River.

The completion of the GWRS reflects a decades-long effort by OCWD and OC San to invest in a more resilient water supply and builds upon its legacy of reusing a once wasted resource. The GWRS has garnered global attention for its innovative approach and use of technology, and it continues to serve as a blueprint for other agencies around the world. To maintain its longstanding commitment to educate communities about water reuse, OCWD continues public outreach through an active speaker’s bureau program, meetings and presentations, and facility tours.

Read more about this world-class system here.