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Orange County Groundwater Replenishment System

Location Information: Orange County, California United States

GIS Data:

Project Type(s): Drinking Water and Wastewater

Project Owner/Agency: Orange County Water District and Orange County Sanitation District

Budget: Over $10,000,000

Envision Rating: Not Rated


This project is the world's largest wastewater purification system for indirect potable reuse. The Groundwater Replenishment System (GWRS) 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 exceeds all state and federal drinking water standards. Operational since January 2008, this state-of-the-art water purification project can produce up to 70 million gallons (265,000 cubic meters) of high-quality water every day. This is enough water to meet the needs of nearly 600,000 residents in north and central Orange County, California. The design and construction of the GWRS was a project jointly-funded by the Orange County Water District and the Orange County Sanitation District. These two public agencies have worked together for more than 30 years. They are leading the way in water recycling and providing a locally-controlled, drought-proof and reliable supply of high-quality water in an environmentally sensitive and economical manner.

Triple Bottom Line

Economic: Provides an uninterruptible source of water for seawater intrusion protection and groundwater recharge. Uses less than half the energy required to transport water from Northern to Southern California. Designed to be expanded to increase production capacity to help meet future water needs. Uses one-third the energy required to desalinate seawater.

Environmental: Decreases Southern California's dependency on water from the Sacramento-San Joaquin River Delta and the Colorado River. Creates a locally-controlled, reliable supply of high-quality water that is drought-resistant. Produces high-quality water to replenish the groundwater basin. Protects Orange County's groundwater basin from seawater intrusion. Protects the environment by reusing a precious resource. Reduces the amount of wastewater discharged to the Pacific Ocean. Diversifies water supplies in Southern California, minimizing negative impacts resulting from limitations on imported water supplies, natural disasters, climate change, and/or droughts. Improves groundwater quality by reducing the amount of dissolved solids (salt) in the groundwater basin.

Social: Provides Orange County communities added assurance of sufficient water supplies to support economic vitality. Demonstrates a successful partnership between public agencies. Created jobs from development, construction and operation of the GWRS.

Contact Information

Michael R. Markus, P.E., General Manager
Orange County Water District