GWRS - new water you can count on

GWRS is the world's largest water purification system for indirect potable reuse. The system takes highly treated wastewater that would have previously been discharged into the Pacific Ocean and purifies it using a three-step advanced treatment process consisting of microfiltration, reverse osmosis and ultraviolet light with hydrogen peroxide. The process produces high-quality water that meets or exceeds all state and federal drinking water standards.

View the GWRS technical brochure (PDF)

Reverse Osmosis Trains of the GWRS (Steve Crise, Courtesy of AWWA)

The process

After wastewater is treated at the Orange County Sanitation District, it flows to the GWRS where it undergoes a state-of-the-art purification process.

The process

Frequently asked questions

Frequently asked questions

You have questions? We have answers. Explore some of the GWRS' most frequestly asked questions.

Frequently asked questions

Book a tour

Book a tour

Public tours of the GWRS are offered the first Friday of every month, or other days of the week depending on staff availability.

Book a tour

GWRS final expansion

GWRS final expansion

The Groundwater Replenishment System Final Expansion Project (GWRSFEP) will increase GWRS treatment capacity to 130 MGD.

GWRS final expansion

GWRS is a joint collaboration between OCWD and OCSD.

Orange County Water District Orange County Sanitation District