FOUNTAIN VALLEY, CALIF. — The Groundwater Replenishment System (GWRS) reached a major milestone on Dec. 9 when it marked 100 billion gallons of ultra-pure water produced since going online almost five years ago. The GWRS, a joint project of the Orange County Water District (OCWD) and Orange County Sanitation District (OCSD), takes highly treated wastewater and purifies it through a three-step process that includes microfiltration, reverse osmosis, and ultraviolet light with hydrogen peroxide, resulting in near-distilled quality water. It is the world’s largest advanced water purification facility of its kind, currently producing up to 70 million gallons per day (mgd) of new water.

The OCWD operates the GWRS and manages Orange County’s groundwater basin.

The GWRS enhances existing water supplies by providing a reliable, high-quality source of water to recharge Orange County’s groundwater basin and protect it from further degradation due to seawater intrusion. It has also provided peak wastewater disposal flow relief and indefinitely postponed the need for OCSD to construct a new ocean outfall by recycling wastewater flows that would otherwise be discharged to the Pacific Ocean. The basin has helped Orange County weather multi-year droughts by stabilizing local water supplies and costs to rate payers.

The internationally renowned facility has garnered more than 21 awards including the prestigious 2009 American Society of Civil Engineers (ASCE) Outstanding Civil Engineering Achievement Award for the year’s most outstanding national engineering project, and the 2008 Stockholm Industry Water Award for the year’s most outstanding international water project.

OCWD broke ground in January 2012 on the 30-mgd GWRS Initial Expansion. The $142.7 million project will create an additional 31,000 acre-feet per year (AFY) of new water supplies to serve northern and central Orange County, bringing the total production of the GWRS to 103,000 AFY, enough water for 850,000 people. Construction is estimated to be completed in late 2014.