Tucson is taking its first tentative dip into the sometimes turbulent waters of recycling treated sewage effluent for drinking.

Tucson Water has produced a detailed long-range plan and an accompanying timetable that calls for building a pilot project to recycle wastewater for potable use as soon as three years from now.

The timetable calls for starting construction of a full-scale wastewater recycling plant by the early 2020s. But the timing of these actions is very uncertain, with Tucson Water officials saying they could be stretched back as far as the 2050s, or done much more quickly, depending on how soon the water is needed.

While the plan hasn’t won City Council approval, many council members gave it a relatively friendly reception at a study session discussion last month.

Mayor Jonathan Rothschild and two council members generally endorsed the idea of wastewater recycling for drinking in interviews last week. But they don’t want to commit to building a plant until ensuring that the most advanced technology possible is used and that the public gets far more education about the treatment process.

Wastewater recycling is a very expensive, at times controversial, process, costing many times more than the delivery of Central Arizona Project water to Tucson.

It could, for instance, cost anywhere from $1,500 an acre-foot to $3,300 an acre-foot to treat effluent for drinking, the city’s effluent recycling plan says. Pumping CAP water uphill for more than 300 miles from the Colorado River, by contrast, costs $146 an acre-foot for Tucson Water today, and could rise to $157 an acre-foot in 2015.

But as effluent’s use for drinking grows around the arid Southwest, it’s a water supply that many local officials say is inevitable, given the region’s ongoing drought and population growth. They see it as the region’s only sustainable, locally generated water supply, particularly given the strains on the Colorado River due to continued drought.

“I think it will happen sooner than the 2050s. The technological possibiilties, I know will happen sooner,” Rothschild said. “But this is something you have to go to the community with and have people understand, and the technology has to be pretty good.”

Recycled water has long been disdained by many residents here and elsewhere because of what’s known as the “yuck factor” of drinking treated effluent. But while opponents denigrate the process as “toilet to tap,” officials say they’re confident that the water can be treated to quality as good or better than Tucson’s current drinking water supplies.

One of the keys will be building public trust in whatever technology is employed, the master plan says.

In the coming year, Tucson Water will interview focus groups, make presentations to neighborhood associations and businesses and convene an expert panel to advise it on additional ways of educating the public about such treatment.

Utility officials will conduct studies of where the wastewater would be treated and where to build pipelines taking the water from Pima County’s sewage treatment plants to recharge basins where it would be first placed, then pumped out.

A key unknown in the uncertainty of when such a plant would be built is the precarious state of Lake Mead and the Colorado River in general. They have suffered steadily declining water levels and flows since 2000 because of the drought and the Southwest’s annual removal of about 1.2 million acre-feet more water from the lake than what the river delivers.

If those trends continue, Hoover Dam’s power output eventually would be sharply curtailed, and Las Vegas would be unable to go deeply enough into the lake to get its water. Also, federal and state officials may have to consider reducing deliveries of river water to Arizona cities and Indian tribes in the 2020s to keep the lake from falling so low that it would reach “dead pool,” in which no water could be pulled from it.

Until recently authorities had said they don’t believe urban CAP shortages would occur until the 2030s or 2040s and some officials remain confident that’s the case, but others disagree.

Or, the federal government may have to consider intervening and overturning a century’s worth of water law to ensure adequate supplies for Arizona cities and Indian tribes — at the expense of other parties with rights to the river.

“The timeline for reuse can move one way or the other,” said Jeff Biggs, Tucson Water’s interim deputy director and recycled water’s program manager. “A lot will depend on future shortages. That could affect our CAP allocation.”

As of now, Tucson Water says that if its CAP supplies hold out, it won’t need a new supply until maybe 2050. But at the same time, it might make sense to have a recycled water system ready in case it’s needed sooner, Councilman Paul Cunningham said.

“Even if we have enough potable water in 2025, wouldn’t it be nice to know that just in case the bottom falls out of the boat we still have contingency water supply online?” he said. “We also need to press on with efforts to capture stormwater and encouraging Tucson Water customers to go to rainwater harvesting.”

It makes business sense to try to use treated water for ratepayers for beneficial use, but officials need to make sure that there’s no “rate shock,” Biggs said.

“It would be cheaper to do it in 10 years than in 20 years. If we knew for sure shortages would be happening within the next decade, we’d speed this process up, but then again, we’d have to look at our capital improvement program. We’d have to see what projects to move further back. We can’t pay for everything,” Biggs said.

Councilman Steve Kozachik, a frequent critic of Tucson Water, agrees that recycling is inevitable. He adds that the city needs to be sure that it’s getting the most advanced technology so “we’re not using today’s technology and closing our mind to technological advancement.”

At the same time, he said he believes that the situation with Lake Mead is more serious than many people, including Tucson Water’s staff, think — meaning recycling may have to start sooner than many authorities would expect.

“People are really turning a blind eye to this right now,” Kozachik said. “People need to get the revelation that this is a serious issue — not 50 years from now but now.”

The city is already recycling lots of wastewater now, for irrigating parks, golf courses and school grounds and residential lawns, among other places. Today, the city’s reclaimed water system has more than 900 such customers who use reclaimed water in place of potable water, generally on turf.

In 2012, approximately 61,400 acre-feet of recycled water was produced by Pima County’s various reclamation facilities. The city of Tucson is entitled to take 21,000 acre-feet of that — enough to serve at least 50,000 homes if the water was drinkable — but it currently takes only about 13,400 acre-feet for turf irrigation or to recharge for future use.

The remaining 11,700 acre-feet of city-owned effluent rolls down the Santa Cruz River — a boon for cottonwood and willow trees that support bird life, to be sure. But Tucson Water’s recycled water master plan sees that differently: “A significant portion of the city’s entitlement left its service area as surface flow after it was discharged to the Santa Cruz River channel without further physical or economic benefit to the city.”

By 2030, as the region’s population grows, the amount of available effluent to the city could rise to as much as 46,000 acre-feet, the wastewater master plan says.

The projections indicate that the city’s annual effluent share could reach up to 46,000 acre-feet by 2030. Of that, about 29,000 acre-feet would be unused. That’s more than twice as much unused effluent as the city says is available today.

Contact reporter Tony Davis at tdavis@azstarnet.com or 806-7746. Follow Davis on Twitter@tonydavis987.