You’ve heard the tale before, “one man’s trash is another man’s treasure.” Allow us to tell you a story, a wastewater story, where water that was destined to be released into the ocean found a new purpose when two agencies dreamed of a better way, where that very water could be collected, treated, and cleaned to quench the thirst of millions.
What is the GWRS?
The Orange County Water District (OCWD) and the Orange County Sanitation District (OC San) dreamed of finding a better way to address the water supply problems they faced. For OCWD, it was tackling issues with seawater intrusion, where saltwater finds its way into freshwater aquifers and can contaminate the groundwater. For OC San, it was the challenge of building a second ocean outfall, which is a 10-foot diameter offshore pipeline that connects wastewater treatment plants to the ocean, allowing the treated water to be released five miles from shore and about 200 feet below the ocean surface into the sea.
Over a glass of purified water, they wondered what could be done. The result was the Groundwater Replenishment System (GWRS), which is not only a creative solution to meeting the water supply needs of the region, but also makes history as the world’s largest advanced water purification system for potable reuse.
To water this down into simple terms, this facility takes treated wastewater that would have been released into the ocean and creates a dependable and safe supply of drinking water for the community. GWRS has been operational since 2008 and recently completed its final expansion in 2023. This marks an incredible milestone where 100% of OC San’s reclaimable wastewater is recycled through groundwater recharge before being pumped out to provide water to one million people daily, averaging about 130 million gallons of water being produced day after day.
The GWRS has become an essential source of water for Orange County, which wouldn’t have been possible without the collaboration between OCWD and OC San. Let’s take a closer look at these two agencies and their role in providing high-quality water for the region before breaking down how the GWRS plays a role in our day-to-day life
Who is OCWD?
OCWD provides groundwater for 19 cities and retail water agencies, serving 2.5 million residents in north and central Orange County. OCWD has been entrusted to guard the region’s groundwater basin. It manages and replenishes the basin, ensures water reliability and quality, prevents seawater intrusion, and protects Orange County’s rights to Santa Ana River water.
Who is OC San?
OC San is a public agency that provides regional wastewater collection, treatment, and recycling for 2.6 million people in central and northwest Orange County. OC San has two operating facilities that treat wastewater from residential, commercial, and industrial sources. The wastewater from these communities travels through 388 miles of regional sewers to one of the two treatment plants in Fountain Valley or Huntington Beach where it is treated and sent for recycling or released into the Pacific Ocean.
How does the GWRS work?
Now that you have background on these two agencies, let’s look at their role in the GWRS. OC San treats wastewater and sends it to the GWRS for further purification, instead of releasing it into the Pacific Ocean. This treated wastewater is purified at the GWRS using a three-step advanced process consisting of microfiltration, reverse osmosis, and ultraviolet light with hydrogen peroxide. This purification process produces high quality water that meets state and federal drinking water standards. This purified water is then injected into a seawater barrier or pumped to recharge basins where it naturally percolates into the Orange County Groundwater Basin and supplements Orange County’s drinking water supplies.
What are the benefits?
In addition to reducing the amount of water released into the ocean, GWRS water improves water quality in the basin and offers a more cost-effective and energy-efficient alternative than bottled water. Some other benefits of the GWRS are that it:
- Provides a reliable supply of high-purity, near-distilled quality water even during drought
- Offers a more cost-effective and energy-efficient strategy than importing water from distant sources (uses half the energy required to import water and one-third the energy required to desalinate seawater)
- Provides a measure of protection from variations in the availability of imported water supplies
- Creates a hydraulic barrier that prevents seawater intrusion into drinking water wells
- Recharges groundwater supplies and minimizes overdraft
- Improves water quality in the basin
- Reduces the volume of treated wastewater discharged into the ocean and puts it to beneficial use
- Reduces the region’s need for imported water
- Recycles 100% of OC San’s reclaimable wastewater flows
- Produces water at a more affordable cost
- Meets all state and federal drinking water standards (these regulations are different than bottle water)
A legacy that will live on
The GWRS offers a solution to the decade-long effort of finding a way to sustain a more resilient watershed. OCWD and OC San took what was once a wasted resource and turned the process of reclaiming and reusing that resource into a project that has garnered global attention for its innovative approach to preserving clean water for the future.
The GWRS has received more than 80 awards and international media attention. It also holds the Guinness World Records™ title for the most wastewater recycled to drinking water in 24 hours. The legacy of this project will continue to serve as a blueprint for other agencies around the world, leading to water supplies that communities can trust and depend on.
Bonus: Check out this article on the Guinness World Record that the GWRS holds.
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