Tuscon residents may soon be drinking treated wastewater as part of a growing national trend to offset diminishing freshwater sources.
Faced with increasing demand for water, Tucson Water Company has recommended that the city eventually use its growing stream of sewage to augment its drinking water. Using a procedure known as the Fountain Valley process, Tucson Water could completely close the gap that will emerge in the coming decades between Tucson's demand and supply.
"You could offset it all" with treated water, says Tucson Water Director David Modeer in an article by B. Poole in the Tucson Citizen. Treated sewage is much cleaner than what most Tucson citizens are drinking now, called the Clearwater blend of Avra Valley ground water and Colorado River water. The river contains chemically treated wastewater from cities upstream, along with traces of chemicals, hormones and drugs that a system such as Orange County's would remove.
The Fountain Valley process involves chemical treatment, filtering, more filtering, radiation zapping, and more chemical treatment. It yields water that is nearly distilled, which is then injected into the underground water supply. Orange County has been using the process since January, and its success could serve as a road map to Tucson's future.
Even Tucson's most vocal critic of drinking wastewater can't deny that water put through the Fountain Valley process is clean. "Given enough money, you can treat water to make it pure -- more pure than what we're drinking now, for sure," said former state legislator John Kromko, who last year spearheaded an effort to ban the use of wastewater in drinking water.
As people from south of the border flood into California and Arizona, the Orange County Sanitation District realized growth would soon force it to build a new pipe to push treated sewage into the ocean five miles offshore. While environmentalists watched and construction costs swelled, the utility sought a partnership with the water district.
The partners began designing a treatment plant that would keep sewer outflow to a minimum, save money, and decrease dependence on imported water. Like Tucson's effluent, more than half of which is dumped into the Santa Cruz River, the Orange County wastewater was flowing out of the district unused.
"We're taking a source of water that would otherwise be wasted to the ocean," said Mike Markus, Orange County District General Manager.
In order to end up with water that is more pure than other water the district uses, it is first chemically treated by the sanitation district. Then large particles are filtered out and the water district pushes the water through membranes to get rid of all but the smallest molecules. Then it is sanitized with ultraviolet radiation and hydrogen peroxide.
Modeer claims the purity of Orange County water could be achieved for Tucson. "Water is water. Water is just H2O, and we can get it down to just H20 ... You can take everything out, then you can add back what you want."
Kromko, whose proposed ban on the use of treated wastewater in the drinking water supply was rejected by voters, does not dispute that. But he fears such a plant would encourage growth, which would make Tucson more vulnerable to drought and resulting shortages from the Colorado River.
But some see growth as actually being the source of the water. By 2030, if the city's population projections hold true, Tucson will own about 20 billion gallons of effluent per year. About a third of that would be used on park, school and golf course turf. The rest would be available to use as drinking water -- enough for about 150,000 families.
Although some people express disgust at the thought of drinking treated effluent, many others have been drinking it all their lives. In most cities along America's rivers, wastewater is chemically treated, then returned to the rivers to be used as drinking water downstream. This treatment leaves behind traces of chemicals and drugs that eventually wind up in the drinking water. Virtually every major waterway in the nation contains treated effluent.
For Tucson, the City Council, not the public, will decide whether to blend treated effluent with drinking water, although the decision remains some years away.
City Councilman Steve Leal sees "the only reason you would need that plant is to serve people who don't live here yet." The cost would be substantial. The cost of the Orange County plant was $490 million.
Getting past the "ick factor" is also seen as necessary. The Orange County district faced little public objection, possibly because of its carefully laid plans to get its elected board behind the effort.
A similar effort could be done in Tucson, says Modeer. "We went to the moon, we can do this, too. I think the general public is beginning to understand that."