The following information answers some of the frequently asked questions we have received on the Orange County Water District's Groundwater Replenishment System (GWRS) and its impact on drinking water quality and water safety.

GWRS is a system that cleans wastewater and returns it to recharge basins in Anaheim where that water is further cleaned by layers of soil and rock, and ultimately refills local water aquifers over time.  The system is operated by the Orange County Water District (OCWD).  Anaheim, as well as 19 other Southern California cities, pump much of our drinking water out of these local aquifers. 

Among the questions raised regarding the safety of the water coming from the GWRS is whether a plant failure could allow sewage into the recharge basins. With regard to this, OCWD has assured Anaheim that there are numerous fail-safe systems incorporated into GWRS make this risk quite small. 

As an example, the GWRS plant has an automated control system will start a shutdown sequence if it detects a system failure or contaminants downstream of a treatment process. Backing up the automated system are two system operators who are on duty 24/7, in addition to a full suite of security measures. Finally, there is a considerable amount of time between when treated water leaves the treatment plant in Fountain Valley until it reaches the recharge basins in Anaheim. Thus, if an inappropriate condition is noted at the plant, pumps can be shutdown in plenty of time to prevent contaminants from reaching the recharge basins. OCWD involved health experts from throughout the country to review of the plant’s operating procedures.   

Nevertheless, unexpected things can always happen. That is why it is important to remember that GWRS water does not go directly into your drinking water. Instead, it goes into recharge basins where it will be naturally filtered by thousands of feet of soil where it will remain in the ground for well over a year before it ever reaches a drinking water well. Numerous studies bear out the fact that bacteria and pathogens are killed by this process alone.

To put this in perspective, consider that non-GWRS water which currently flows in the Santa Ana River. This water, which already goes directly into the recharge basins, includes floodwaters, street runoff, and effluent from treatment plants in the Inland Empire. 

By contrast, according to OCWD, “GWRS water will undergo one of the world's most advanced, state-of-the-art, purification processes. Water will be purified using a three-step process of microfiltration, reverse osmosis and ultraviolet light and hydrogen peroxide treatment techniques.”

Additionally, OCWD also states, “Water from the Groundwater Replenishment System will be so pure that it will help soften Orange County's drinking water, by reducing minerals in water that cause corrosion and scaling of plumbing fixtures and appliances.”   

Besides GWRS safeguards, Anaheim is further protected by its own city water utility that continuously monitors water quality at our wells---we conduct over 30,000 water quality tests per year and are scrupulous about remaining under all federal and state standards.  If water quality at an Anaheim well exceeded those limits, we would shut it down promptly.

You can find additional information on the GWRS process by attending one of the numerous tours or presentations that OCWD provides. You can find more information about the GWRS through their website www.gwrsystem.com or by calling OCWD directly at 714-378-3333.