California Explores 'Toilet-to-Tap' Tech

The California drought has brought growing support for 'Toilet to Tap' programs in some communities

As theCaliforniadrought worsens, some communities such as Orange County, San Diego and the Silicon Valley are expanding water recycling programs, and support for "toilet to tap" programs appears to be growing from a once-squeamish public.

"Because a lot of communities are running out of water, they sort of have to explore all their options," said Janny Choy, research analyst with Water in the West, a program of theStanford Woods Instituteand theBill Lane Center for the American Westat Stanford University. "Recycled water is certainly one piece of the puzzle, but it's probably not going to be the answer to solve everybody's problem."

The Silicon Valley Advanced Water Purification Center, located in San Jose, began operations last year and produces up to 8 million gallons per day of purified water from wastewater. The facility was built at a cost of $72 million in a partnership between the Santa Clara Valley Water District (SCVWD) and the city of San Jose. The facility treats wastewater that would otherwise go into the San Francisco Bay for use as reclaimed water in irrigation, construction and industrial uses. They eventually hope to use some of the purified water to refill groundwater sources.

The Santa Clara County facility gets wastewater from the cities of San Jose and Santa Clara, and the goal had been to expand the recycled water to make up at least 10 percent of total county water demand by 2025. But due to the 4-year-old drought, the water agency is pushing its goals further: It's pursuing plans to expedite that goal by three years—to reach the 10 percent number by 2022—and partnering with other cities in the county to purity their water.

"It's a drought-proof supply, and it's also a local supply," said Colleen Valles, a spokesperson for the SCVWD. She said the water agency has five projects pending and is looking at expanding the recycling program in the county.

Meanwhile, the Orange County Water District (OCWD) is undergoing an expansion of its own at the water agency's high-tech Groundwater Replenishment System in Fountain Valley, California. The $481 million plant has been operational since 2008 and currently processes about 70 million gallons of treated sewage wastewater each day into drinking-quality water that goes into groundwater basins for later reuse as potable water. OCWD, which serves more than 2.4 million people, is spending $142 million to increase capacity at the facility to approximately 100 million gallons per day, or enough water for 850,000 residents.

"Recycled water is a huge benefit," said OCWD General Manager Michael Markus. "We can produce the water for about half the energy it takes to import water from Northern California and about a third of the energy it takes to desalinate sea water."

Orange County's plant, for example, can produce recycled water for about $480 an acre-foot—well below the estimated $2,000 per acre-foot a new desalination plant in nearby San Diego County will be paying for new water. Similarly, the recycled water runs about half the roughly $1,000 per acre-foot price of water from the Metropolitan Water District, the giant water wholesaler for Southern California, which on Tuesday announced a 15 percent reduction in the amount of water it will supply to its 26 member agencies.

The OCWD wastewater treatment facility, the largest advanced water purification facility in the Western Hemisphere, uses a three-step water treatment process: micro-filtration, reverse osmosis and ultraviolet light with hydrogen peroxide disinfection. The plant uses about 13 megawatts of power per day, or the equivalent of power to supply 7,500 to 12,000 homes.

"You hear some people talking like, 'I don't want to drink toilet water,' " said Henry Vaux Jr., professor emeritus of Resource Economics at the University of California at Riverside. "Once it's gone through three stages of treatment, the water that ultimately goes out of there is cleaner than they got and flushed away."

California law allows treated wastewater to be used for indirect potable reuse, such as sending the purified water into groundwater basins for capture later as a source of drinking water. A state bill passed in 2013 requires that California's water regulators create a framework for direct potable reuse by the end of 2016.

Purified wastewater could provide enough potable water to supply all municipal needs for more than 8 million people, or roughly one-fifth of California's projected population for 2020, according to a report released last year and sponsored by the WateReuse Association, an organization supported by water utilities and companies that promote water reuse. The report also pointed out that NASA and the International Space Station already use a technology that produces potable water for six crew members from a combination of condensation and collected urine.

In 2014, twoTexastowns launched the nation's first direct-to-potable reuse water programs. Wichita Falls and Big Spring, about 230 miles apart, treat wastewater with a multistep cleaning process and then send the purified water directly to homes. The last U.S. Drought Monitor data shows 49 percent of Texas suffering from some level of drought.

Source: CNBC

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• Sludge Separation
• Water Reuse & Recycling
• Drinking Water