'Toilet to Tap' Water Treatment Will Soon Be Legal in Arizona

Once mocked as “toilet to tap,” the practice of directly treating wastewater for drinking could be legal in Arizona by the end of this year.

The Arizona Department of Environmental Quality is likely to propose legalizing “direct potable reuse” in six months, its senior hydrologist Chuck Graf said this week. Better technology and safety measures now offer assurances the wastewater can be treated for drinking without ill effects, Graf and other officials said.

The first of a series of permitting rules and standards “hopefully can be approved by the end of this year,” Graf said in an interview. The ADEQ, which wants the change, will make the final decision.

Direct reuse has been illegal in Arizona since the state started regulating wastewater in 1982.

“Water reuse’s time has come. It’s a large theme taking place across the U.S. and the world,” Tucson Water director Tim Thomure told a state water recycling committee this week in Phoenix.

“We have had knowledge that this would be needed sooner rather than later. Later has become sooner,” he said.

But while water utility officials around the state are pushing for more liberal policies for treating wastewater for drinking, such treated water isn’t likely to be flowing from Tucson-area taps soon.

The practice is likely to begin first in places such as the Prescott Valley and mountainous or other less urban areas where water resources and the ability to recharge water for future use are limited, said Thomure, who chairs a statewide steering committee on the issue. In those areas, it will be at least two or three years before they’re ready to use it, he said.

Direct potable reuse involves piping wastewater from a conventional sewage treatment plant to another, more technologically advanced plant that treats the water to drinking quality. A reverse osmosis plant, which runs wastewater through membranes for treatment, is one of several technologies available.

This practice contrasts with indirect potable reuse, in which utilities recharge treated wastewater into the aquifer and pump it out for drinking. That happens along the Lower Santa Cruz River in the Tucson area, where two Pima County treatment plants discharge millions of gallons a day.

The idea of treating wastewater for drinking once was criticized by some environmentalists, who saw it as an effort to find more water to serve continued population growth rather than controlling or limiting growth.Others, concerned about potential health impacts, mocked the practice as “toilet to tap.”

But in a new report, the environmental group Western Resource Advocates included direct potable reuse on a list of solutions to ease the pain of future Colorado River shortages.

With direct potable reuse, you don’t have to recharge the water underground or pump it back out, which saves money, said Linda Stitzer, a water policy adviser for Western Resource Advocates in Tucson.

“Right now, we’re limited to using (effluent) on golf courses and parks or recharging it,” Stitzer said. “By directly treating it to a higher standard … you have a whole new group of users.”

However, Tucson Water officials are no longer talking regularly, as they used to, of treating wastewater to drink possibly by the 2020s, to respond to population growth and drought pressures on the Colorado River.

Officials of the Marana, Oro Valley and Metro Water District water utilities say they also don’t expect to need direct potable reuse in the near future.

Marana’s treatment of its wastewater will be different, for instance. Starting in 2018, when it finishes construction of a sewage treatment plant along the Santa Cruz, it will recharge treated wastewater into the ground, said John Kmiec, Marana’s water director. That will provide water storage credits the town can draw upon to pump out water elsewhere, using existing wells.

But, “if a community wants to look at direct reuse when it may be more efficient in the future, it should have the option and not be prohibited,” said Kmiec, who chairs a statewide water recycling committee.

Drought is a key factor driving many states to consider direct potable reuse. In Arizona, a bigger factor may be that ADEQ is now revising what Graf calls its “pretty aged” overall water reuse regulations, unchanged since 2001. Water utilities want the direct reuse approved now because it may be years before the rules are revised again.

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Taxonomy

• Treatment
• Water Reuse & Recycling
• Water Recycling
• Reuse
• Recycling