Holding a plastic cup within the Orange County Water District’s  


Groundwater Replenishment System (GWRS), program manager Shivaji Deshmukh announces a fact that might make some people’s stomachs turn.             

 “An hour and a half ago, this was treated sewage,” he says. “A day ago, it was raw sewage.”


Having complete faith in the project and its end result, Deshmukh then downs the water without blinking.


An ingenious method to fight California’s water shortage, the GWRS takes an unlikely resource—sewage flushed down the toilets in Southern California’s Orange County—and transforms it into drinking water that exceeds all state and federal drinking water standards.


Before taking the gulp of refreshing purified water, Deshmukh led me on a tour of the facility, which took about an hour, the approximate amount of time it takes the treated sewer water to pass through three processes before becoming drinkable. Costing $480 million to construct, the state-of-the-art water purification project has been up and running since January 2008.


The Groundwater Replenishment System is in an ideal location: just feet away from the Orange County Sanitation District (OCSD), where the sewage from northwest Orange County is treated. Every day, OCSD sends water over to the GWRS through a .8 kilometer (.5 mile) long, 2.4 meter (96-inch) pipe. Former public affairs manager for Orange County Sanitation District, Michael Gold, explains the kind of water his neighboring facility receives: “When it comes in [to the OCSD], it’s dirty,” he says. “It’s smelly. It’s full of viruses and junk. As it comes out of our plant, it looks clean, but it’s not clean enough to swim and bathe in.”


Currently, OCSD sends about 378 million liters (100 million gallons) of treated sewer water over to the GWRS for recycling every day. Gold says that amount of water is roughly enough to fill up nearby Anaheim Stadium, home to Major League Baseball’s Los Angeles Angels of Anaheim.

Three Processes


After OCSD sends treated water to the GWRS, it undergoes three processes to make it drinkable: microfiltrationreverse osmosis, and ultraviolet disinfection.


The first process is microfiltration. Deshmukh said this gets rid of bacteriaprotozoa, and suspended solids in the liquid by pushing it through a series of fiber membranes filled with tiny, hollow tubes. He compared it to drinking iced soda through a straw. The pollutants are like the ice, which are too large to be drawn up through the straw.


The water is propelled through the microfiltration membranes with giant, 600-horsepower engines. Following microfiltration, the water sits in a large holding tank.


“This R.O. plant is one of the biggest in the world,” Deshmukh said.


Inside, the facility looks like a warehouse filled with stacks of plastic pipes.


“The water we get here has been microfiltered, but now we have to take the organics, the pharmaceuticals, the viruses, and salts out of the water,” Deshmukh said.


During reverse osmosis, specially made plastic sheets allow the passage of water while harmful material as small as a molecule is separated out. “This is the heart of the treatment process,” Deshmukh explained. “This allows us to make the water potable.”


In reverse osmosis, conducted by OCSD, the water is pushed through plastic sheets by 1,000-horsepower engines. The program manager insists that the energy used in treating the water is worthwhile when compared to other methods of supplying Orange County with water. One popular method is shipping water from northern California.


“Reverse osmosis uses a lot of energy, but when you compare it to pumping water over a mountain range [the Sierra Nevada, California], it’s less,” he said.


After Deshmukh taught me about the reverse osmosis process, we stepped outside into the Orange County sun and walked towards the final stage the former sewer water had to be put through. We stopped at a series of steel cylinders that are filled with ultraviolet light bulbs. Ultraviolet disinfection destroys any of the water’s remaining viruses. 


“This is the last step,” Deshmukh said. “After this, we actually add minerals back to the water.”



It’s here where Deshmukh and I tip back our plastic cups filled with the newly treated water and drink in a liquid that may have been swirling around a toilet bowl just a day ago. But this water actually has months to go before it will flow out of any of Orange County’s taps.


About 132 million liters (35 million gallons) of the water treated by GWRS is injected into Orange County’s seawater barrier. The barrier, a series of wells that function like a dam, helps keep the region’s aquifers, or underground freshwater supply, from being overtaken by seawater from the nearby Pacific Ocean.


About 246 million liters (65 million gallons) of the water is pumped 21 kilometers (13 miles) away to Anaheim, where it is discharged into several lakes. From there, it joins the region’s rainwater and settles into aquifers as groundwater. In approximately six months, the groundwater is chlorinated by the cities of Orange County and sent to taps for personal and business use.


As of 2015, the Orange County Water District treated 378 million liters (100 million gallons) of water daily, the amount that would meet annual water needs of 850,000 people.


In addition to creating a renewable source of fresh water for the area’s growing population, another benefit is that the GWRS reduces the amount of treated wastewater discharged in the Pacific Ocean.


Though the initial idea of drinking reclaimed water might make some stomachs turn, the success of Orange County’s Groundwater Replenishment System has caused a turn in California’s thinking about the idea of transforming sewer water into drinking water. This change has resulted in a series of proposals for similar facilities across the state.


From Toilet to Tap
Shivaji Deshmukh takes a sip.

Water Wisdom
Before the Groundwater Replenishment System began processing treated sewer water in January 2008, the Orange County Water District's Water Factory 21 was the first facility to use reverse osmosis to make municipal sewer water into purified drinking water.


generally or near an exact figure.


an underground layer of rock or earth which holds groundwater.

Plural Noun

(singular: bacterium) single-celled organisms found in every ecosystem on Earth.


chemical substance containing the element clorine (Cl).


management of a natural resource to prevent exploitation, destruction, or neglect.


machine that converts energy into power or motion.


to go beyond the limit.


a building or room that serves a specific function.


having to do with a nation's government (as opposed to local or regional government).


long, thin, threadlike material produced by plants that aids digestive motion when consumed.


water found in an aquifer.


structure used for sheltering airplanes.


unit of measurement for the power of engines. One horsepower is equal to 550 foot-seconds of power, or 745.7 watts.


very clever or smart.




watering land, usually for agriculture, by artificial means.


thin coating of material that certain substances, such as water, can pass through.


water sanitation process that removes bacteria, protozoa, and suspended solids.


inorganic material that has a characteristic chemical composition and specific crystal structure.


smallest physical unit of a substance, consisting of two or more atoms linked together.

mountain range

series or chain of mountains that are close together.


community unit, such as a city or town.


composed of living or once-living material.


drug or having to do with drugs and medications.


chemical or other substance that harms a natural resource.


suitable for drinking.


to push forward.


suggested plan.


one-celled organisms in the kingdom protista, such as amoebas. (singular: protozoan)

purified water

water that has had all pollutants and harmful chemicals removed.

raw sewage

liquid waste from homes and industry.

renewable resource

resource that can replenish itself at a similar rate to its use by people.

reverse osmosis

water sanitation process that forces water through plastic sheets in order to remove microscopic pollutants and harmful molecules.


(sodium chloride, NaCl) crystalline mineral often used as a seasoning or preservative for food.

seawater barrier

series of wells, filled with freshwater, that work as a dam to prevent seawater from entering a region's aquifer.


metal made of the elements iron and carbon.

suspended solid

particle larger than 1 micrometer that is dispersed in a fluid. Used to measure water quality.


to change in appearance or purpose.

treated sewage

wastewater that has had most toxic materials removed by physical and chemical processes. Treated sewage is not safe to drink or bathe in.

ultraviolet disinfection

water sanitation process that uses ultraviolet radiation to remove harmful viruses.


pathogenic agent that lives and multiplies in a living cell.


large building used for storing goods.