As the California drought 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 the Stanford Woods Institute and the Bill Lane Center for the American West at 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 (Tweet This). 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.
"It's a drought-proof supply, and it's also a local supply."
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.
Saving money
"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.
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