A new treatment plant in Orange County, Calif., is one of about 15 in the country to recycle wastewater back into the groundwater drinking water supply -- a plan called indirect potable reuse. Two experts answer your questions on water recycling.
How is what Orange County is doing different from what happens in most water systems in this country?
How is Orange County's system different from most water systems? Isn't wastewater supposed to be processed according to government standards then returned to the aquifer then ultimately drawn into the water supply and processed into potable water?
Cheryl McGovern responds:
Our water quality is regulated through two federal laws and many state laws. The Clean Water Act governs wastewater treatment and surface water quality. The Safe Drinking Water Act governs the protection and treatment of drinking water and ground water supplies. The CWA regulates discharges into waters of the U.S. through a permit program. The terms "pollutants" and "waters of the U.S." are defined further by water quality criteria to protect different beneficial uses of the water and generally waters of the U.S. are defined as surface waters.
Most water systems in the U.S. draw their water from a natural source -- surface water or a groundwater aquifer that is mainly recharged by sources other than treated wastewater effluent.
Orange County is treating wastewater to meet federal water standards under the Safe Drinking Water Act and Clean Water Act. Other water systems in this country don't treat wastewater to this high level of quality, as they discharge treated wastewater to surface water, such as a river or ocean, using a permit which includes pollution discharge limits based on CWA receiving water beneficial uses.
Beneficial uses and the quality of water necessary to protect them are established by individual states for different classes of water or water segments. Common beneficial uses include aquatic life, recreational and agricultural uses. The quality of water required to protect these uses (under CWA) is different than the quality of water required to meet drinking water standards (under SDWA).
However, the same water body that receives wastewater discharges may serve as a drinking water source further downstream, so all drinking water must meet SDWA regulations when it is comes out at the home faucet.
The Orange County Groundwater Replenishment Project uses reclaimed wastewater to recharge the drinking water aquifer with more advanced treatment of wastewater using water purification processes -- including microfiltration, reverse osmosis, ultraviolet light and hydrogen peroxide -- that treat the water to very high levels that meet state and federal drinking water standards before the highly treated water is returned to the groundwater basin, where it blends with other waters and is buffered with natural minerals before it enters the local drinking water supply.
Shivaji Deshmukh responds:
The Groundwater Replenishment System is a groundwater management and water supply project that supplements existing water supplies by providing a new, reliable, high-quality source of water to recharge the Orange County Groundwater Basin and protect it from degradation due to seawater intrusion. What makes this project unique is that the source water is treated sewage. Orange County Water District and Orange County Sanitation District constructed this project to, also, help defer the need for the construction of another ocean outfall which would discharge wastewater.
Many water providers within the United States draw their water from surface water (rivers, lakes, etc.) or groundwater, treat it, and deliver it to their residents. If these bodies of water have upstream agencies discharging highly treated wastewater into them, then they are generally considered "unplanned" indirect potable reuse. The GWR System is a planned indirect potable reuse project which means all the purified water is recharged into the environment prior to being ultimately pumped back out and delivered to the residents of North and Central Orange County.
The water produced out of the GWR System is not similar to other recycled water. The water meets and exceeds all federal and California state drinking water standards. After treatment, it is the highest quality water of all sources in Orange County. Many other recycled water projects are used for non-potable applications like watering lawns, golf courses or greenbelts.
The GWR System facility purifies the highly treated sewer water by using a state-of-the-art, three-step process -- microfiltration, reverse osmosis and ultraviolet light with hydrogen peroxide. The water has already been treated twice by the Orange County Sanitation District.
OCWD experts have been testing the water purification technologies used in the GWR System for more than a decade. Constant water sampling and testing is part of the GWR System program to ensure water safety. Furthermore, the GWR System must be reviewed, approved and permitted by the California Department of Health Services and California Regional Water Quality Control Board to ensure public health, water quality and environmental compliance.