If It’s Brown, Drink It Down
Timing, they say, is everything.
In the late 1990s, government officials in San Diego, worried that just 10 percent of the municipal water supply came from local sources, approached residents with a proposal to help wean the city off imported water. The city wanted to build a facility that reclaimed water from the wastewater treatment plant and added it to San Diego’s drinking water. When groups rallied to oppose the project, voicing concerns over public health, the City Council decided to kill it.
In 2012, the city launched a demonstration project to test the viability of potable reuse. This time the public was on board. “When we talk to people, one of the topics of conversation is the idea of local control and generating water supplies,” says Marsi Steirer, water purification demonstration project director.
For a year, the Advanced Water Purification Facility reclaimed one million gallons of effluent daily and treated it to a level clean enough to drink. The project included extensive testing at each step of the process, along with a multi-pronged education program inviting people to take virtual and actual tours of the facility. The next step is to build a full-scale facility, which will process 15 million gallons per day. If all goes according to plan, by 2020 nearly 30 percent of San Diego’s water will be coming from local sources or treated wastewater.
illustration pablo iglesias, www.pabloi.com
“That is attractive to people,” Steirer says. “People don’t want to be at the mercy of circumstances beyond their control.” A 2012 public opinion poll showed 73 percent of residents in favor of using advanced treated recycled water.
San Diego is at the cutting edge of a nationwide effort to increase the use of reclaimed wastewater. As freshwater supplies become increasingly tight, water management experts say many communities will have little choice but to recycle their own sewage to keep the taps flowing.
Already, many communities across the US use highly treated effluent for irrigation, dust control and industrial applications such as power plants’ electricity generation. This “reclaimed water” is kept separate from the potable system, often in easily distinguished purple pipes. But so-called “toilet to tap” scenarios are still taboo.
A 2012 white paper by the National Water Research Institute describes the potential benefits of potable reuse projects: reduced energy use (and cost) associated with transporting water; less pressure on over-drawn aquifers and rivers; and, perhaps surprisingly, better water quality. Wastewater recycling is also cheaper and less energy intensive than desalination, and doesn’t have the burden of salt waste disposal.
Today, the town of Big Spring, Texas is the site of one of the country’s most progressive “direct potable reuse” facilities in the country. (The spring that gave the town its name was pumped dry by 1920.) This “raw water production facility” purifies effluent from the adjacent wastewater treatment plant. From there it is blended with other source water before going to one of five regional municipal drinking water plants. The Big Spring facility, which utilizes a similar treatment train as San Diego, provides between 5 and 20 percent of the region’s total source water, depending on the season.
John Grant, general manager of the Colorado River Municipal Water District, says he is “very comfortable” with the water’s quality. “Here in West Texas, people know the value of water,” he says. “But if I told you everyone was excited about the idea, I wouldn’t be telling the truth.”
Proceeding with caution is probably the best approach given a still-squeamish citizenry. The community of Brownwood, Texas is poised to become the first in the nation to implement a direct-potable reuse project that doesn’t include blending with other source water. The proposed facility would process 1.5 million gallons per day, and lessen pressure on Lake Brownwood, which sank to record low levels in recent years. Although the Texas Water Development Board approved a loan for construction of the facility at the end of 2012, the project has stalled, partly because of residents’ opposition. Meanwhile, the county’s irrigation district is testing the possibility of drilling more wells.
Perhaps the timing for wastewater reuse still isn’t right.