The Groundwater Replenishment System (GWRS) won top honors at the 2023 American Society of Civil Engineers Orange County (ASCE OC) awards ceremony, bringing home awards for Outstanding Water/Wastewater Treatment Project and Project of the Year.

A joint project of the Orange County Water District (OCWD; the District) and the Orange County Sanitation District (OC San), the GWRS was recognized for the completion of its final expansion, which recycles 100 percent of OC San’s reclaimable wastewater flows and produces 130 million gallons of water a day (MGD), enough to serve nearly one million people.

“The completion of the GWRS reflects a decades-long effort to invest in a more resilient water supply,” said OCWD Board President Cathy Green. “Thank you to the American Society of Civil Engineers for recognizing this milestone and our legacy of innovation.”

The GWRS takes highly treated wastewater that would otherwise be discharged to the ocean and purifies it using a three-step advanced treatment process consisting of microfiltration, reverse osmosis, and ultraviolet light with hydrogen peroxide. The result is high-quality water that is pumped to recharge basins in Anaheim where it naturally percolates into the Orange County Groundwater Basin, managed by OCWD, 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.

Operational since January 2008, the GWRS began producing 70 MGD and increased production to 100 MGD after an initial expansion was completed in May 2015. In March 2023, the final expansion was complete, and the facility has produced more than 400 billion gallons of water and counting.

“From what was once the “unthinkable” – purifying wastewater into drinking water – is now the model for water reuse, and it is happening right here in Orange County,” said OC San Board Chairman Chad P. Wanke. “We are proud that the GWRS has again made history with the final completion that recycles all of our agency’s reclaimable wastewater flows.”

Reaching this milestone of recycling 100 percent of OC San’s reclaimable wastewater flows enhances efforts to protect public health and the environment by reusing this valuable resource. In addition to reducing the volume of treated wastewater discharged into the ocean, GWRS water 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.

Over the years, GWRS water has become a primary source used to refill the groundwater basin and has enabled OCWD’s 19 cities and local water retailers to pump more water from the basin and become more locally sustainable. For more information, the public is invited to join a virtual facility tour, watch an on-demand tour video, or visit the GWRS website.