Toilet to tap provides millions of gallons of drinking water a day

In Local News, News, State News
From right to left, water is purified using the three-part GWR process. (Courtesy of Maya Sugerman for KPCC)
From right to left, water is purified using the three-part GWR process. (Courtesy of Maya Sugerman for KPCC)

Toilet to tap may not be the most appealing name for a water replenishing system, but it’s adding millions of gallons of drinking water for Orange County residents to use.

The constant need for new fresh water is being met in part by recycling waste water to use as safe drinking water for thirsty cities. Without processes to recharge incoming rainwater, much of the local underground sources would be in danger of running low.

Orange County Sanitation and Water Districts have made water recycling safer than ever with the Groundwater Replenishment System, a filtration system that turns sewer water into clean drinking water, said Gina Ayala, principal communications specialist at the Orange County Water District.

Initially, waste water is treated at the Orange County Sanitation District to remove impurities in a multi-step process. From there, it is sent on to the replenishment system for further treatment.

The replenishment process consists of three filtration steps–microfiltration, reverse osmosis and treatment with hydrogen peroxide and ultraviolet light.

The first step passes the water through microscopic fibers to separate out any remaining solids, bacteria and some viruses.
Following that, it moves on to a reverse osmosis process where high pressure forces the water through molecular membranes made of plastic.

This second stage removes dissolved chemicals, viruses and pharmaceuticals still in the water.

Finally, the water is treated with ultraviolet light and hydrogen peroxide to rid it of any organic compounds that may still remain.

The water is then sent into the Orange County Water Basin where it is mixed with imported water, rainwater and water from the Santa Ana River to increase the local drinking water supply, Ayala said.
The process results in drinking water that meets or exceeds state and federal drinking water standards, according to the OC Water District.

The water district manages the OC groundwater basin, which provides water for over two million people in Orange County, Ayala said.
The basin currently provides 70 million gallons of water a day, a number that is expected to grow to 100 million gallons a day next year.

The replenishment system is currently undergoing construction to increase its output. Alone, it is enough to sustain 850,000 people. This is only an initial expansion of the system’s capacity–in its final expansion it will be able to produce 130 million gallons per day.

If the drought persists, this method of water treatment will be one of the most cost-effective and environmentally friendly options available.

North county cities like Fullerton get water from OC Water District’s groundwater source at about a third of the cost of what South OC pays per acre-foot (326,000 gallons) of their imported water, according to Greg Woodside, executive director of planning and natural resources at the OC Water District.

Groundwater will eventually run out, meaning other solutions like an increased use of stormwater, desalination and continued conservation will still be necessary long-term methods of addressing the water shortage.

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