About GWRS

The world's largest advanced water purification system for potable reuse

Operational since January 2008, the Groundwater Replenishment System is a state-of-the-art water purification project that can produce up to 100 million gallons (379,000 cubic meters) of high-quality water every day. This is enough water to meet the needs of nearly 850,000 residents in north and central Orange County, California.

The GWRS is a joint project of the Orange County Water District and the Orange County Sanitation District. These two public agencies have worked together for more than 40 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.

To learn more about the project please read the GWRS technical brochure (PDF).

Project benefits:

  • Decreases Southern California's dependency on imported 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-resilient.
  • Provides Orange County communities added assurance of sufficient water supplies to support economic vitality.
  • Produces high-quality water to replenish the groundwater basin.
  • Protects Orange County's groundwater basin from seawater intrusion.
  • Serves as a blueprint for water agencies throughout the world to help solve their local water supply issues.
  • Protects the environment by reusing a precious resource.
  • Reduces the amount of wastewater discharged to the Pacific Ocean.
  • Uses less than half the energy required to transport water from Northern to Southern California.
  • Uses one-third the energy required to desalinate seawater.
  • Demonstrates a successful partnership between public agencies.
  • Created thousands of jobs from development, construction and operation of the GWRS.
  • Postpones, possibly indefinitely, the need for OCSD to construct a second ocean outfall.
  • Designed to be expanded to increase production capacity to help meet future water needs.
  • Improves groundwater quality by reducing the amount of dissolved solids (salt) in the groundwater basin.
  • Produces water at a unit cost of $525 an acre-foot with subsidies and $850 an acre-foot without subsidies--each less than the cost of imported water.
  • Produces water that meets or exceeds state and federal drinking water standards.