The Groundwater Replenishment System (GWRS) is the world’s largest water purification system for indirect potable reuse.
The system, which is a joint partnership between the Orange County Water District (OCWD) and the Orange County Sanitation District (OC San), 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 all state and federal drinking water standards.