GWRS Final Expansion

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The Groundwater Replenishment System (GWRS) is a collaboration between OCSD and the Orange County Water District and is the world's largest water purification system for indirect portable reuse. The system takes highly treated wastewater that would have otherwise discharged into the ocean and purifies it using a three-step advanced treatment process.  The result is high quality water that meets or exceed all state and federal drinking water standards.  

The GWRS Final Expansion Project will maximize water reuse, reducing the amount of treated wastewater discharged through the ocean outfall.  The project will increase treatment capacity from 100 to 130 million gallons per day; enough water for 1 million people!  

The GWRS Final Expansion project will include expanding GWRS treatment facilities in Fountain Valley, constructing new facilities at OCSD's Plant No. 2 in Huntington Beach and rehabilitating an existing pipeline between Plant No. 2 and the GWRS. There are four main projects:

GWRS_Project Graphic2 Tanks & Pump Station - Two concrete tanks will be constructed, 30 feet high with a combined capacity of six million gallons of reclaimable water. A new pump station will be constructed to pump treated wastewater from the tanks to the GWRS facility in Fountain Valley for treatment and injection into our groundwater basin.

Currently in construction. Deep soil mixing activities scheduled to take place May 2020 - August 2020.  Read the construction notification for more information.

66-inch Trunkline Rehabilitation - An existing pipeline along the Santa Ana River will be rehabilitated.  Treated wastewater from the equalization tanks Plant No. 2  will be pumped through this pipeline to the GWRS.   

Low-Flow Pump Station & Plant Water Pump Station - Reduced treated wastewater flows discharged through the ocean outfall will have effects on the current pumps and piping of the Ocean Outfall System that were built to handle higher flows. Construction of a new low flow pump station is required to handle the reduce daily flows through the ocean outfall. A new plant water pump station will be constructed to support the Headworks Modification project.

Currently in construction. More information can be viewed here.

Headworks Modification - All wastewater flows that enter OCSD are combined at the headworks, the first stop of treatment. Not all wastewater being treated can be used as potable water for GWRS and the headworks needs to be modified to separate and treat wastewater flows from reclaimable and non-reclaimable. 

Non-reclaimable flows have a high concentration of salt that is not suitable for GWRS.

Currently in construction.

View all Construction Notifications.

More information about GWRS can be found by visiting

 For questions please contact the Construction Hotline at (714) 378-2965 or via email at