Special Reports

We have to drink that?

Water, where will it come from? By 2050, Pima County could be home to nearly 2 million people, roughly double today's population. Where will we get the water to sustain us? We can pump only so much from the desert without killing more of our rivers and streams. We're entitled to just a small share of the Central Arizona Project's Colorado River water - a supply that could dry up in times of drought. We're already national leaders in conservation, but cutting back can only go so far since Tucson's water use is expected to rise by 111 million gallons a day - double today's rate. The solution, local experts and officials agree, is hundreds of millions of dollars away. It includes building a plant to turn sewage into drinking water, then letting it seep into the ground before being extracted by wells. And it may require removing salt to make our Colorado River water more palatable. It also means buying water rights from the state's farmers and Indian tribes, who still control and use the vast majority of the state's water. Doing that could sustain us through the century - but it guarantees we'll pay more for the water we use. Tucson is growing so fast in such a dry region that we're headed toward drinking our own sewage. The central element of Tucson Water's plan for the next 50 years - treating wastewater to drink, not just to water golf courses - may seem like something out of science fiction. Or a horror movie. But, water experts and utility officials say, it's essential for meeting our ever-growing thirst. "People just have to get used to the fact that our water resources are limited and that effluent is going to become a more important source as the population here grows," said Gail Cordy, senior hydrologist with the U.S. Geological Survey in Tucson. "We're going to have to use it." The groundwater beneath Tucson isn't about to dry up, but consistent overpumping could drive the water table so low that quality would fall and pumping costs would rise. The water table already has dropped more than 200 feet in Midtown due to overpumping in the 20th century, causing the earth to sink and potentially cracking home foundations. Pumping out more water than rain and snowmelt replenish each year further depletes the groundwater supply, threatening streams, wildlife - and Tucson's growth potential. If the city can't prove it has enough water to support newcomers, the state could prevent Tucson from approving more subdivisions. Finding more water will center around effluent because "it's what we control," said David Modeer, director of the city-owned Tucson Water, which serves three-quarters of the county's residents. "It's local and we own it, but it still would require a lot of work, effort and money to make use of it productively." The effluent supply will grow as Tucson does, but the same can't be said of our annual allocation of Colorado River water, which we'll be consuming completely within 10 years. Colorado River water is salty - its mineral content is about double that of our groundwater - so the more we rely on it, the harder our water will become. Customers could balk at the taste and be forced to replace water heaters and other appliances more often. With our consumption of Colorado River water on the rise, Tucson Water says the city must decide next year whether to build a treatment plant or leave the job of removing salts and minerals up to individual consumers. The need for a sewage-treatment plant is farther off, probably about a dozen years. Each project, in today's dollars, would cost an estimated $250 million, and the sewage treatment plant would cost $13 million a year to operate. That money likely would come from higher monthly water bills, government bonds or impact fees on new water customers. The "yuck" factor

Making effluent drinkable already is done from Singapore to Scottsdale, where purified sewage is injected into dry wells to replenish an aquifer. Tucson Water's effluent plan would be the most ambitious in the state. If it goes through - Tucson Water wants the city council to approve it in the next decade - John Hilyard expects more people will be buying purified water at his Midtown business. "There's a certain yuck factor associated with it," said Hilyard, manager of Water Street Station, 2392 N. Country Club Road. Stay-at-home mom Lu Hawkins, 42, already pays 50 cents a gallon at the store, rather than drink from the tap, because of taste and health concerns. The idea of recycling water so there's a "closed loop" sounds great to Hawkins, but she's not so sure Tucson Water can pull it off. "It's a big leap of faith," she said. A tour of Tucson's existing wastewater plants is unlikely to win many converts to the idea of turning sewage into tap water. At least not at first. Tucsonans who flush a toilet south of the Rillito River add their share to the 41 million gallons of sewage that flow every day into Pima County's Roger Road plant. Sewage makes its way to Roger Road almost entirely by gravity. When it arrives, it's more than 99 percent water. At the start of the treatment process, screens filter out large material, like rags and plastic bags. Workers also have discovered a dead body, aborted fetuses, tires and 2-by-4s. "Anything anyone can stuff down a manhole," superintendent Helen Rhudy said. "You'd be surprised what people flush down their toilets or put down their drains." The big debris is fed onto a conveyor belt for disposal in a landfill. On a recent visit, that belt also carried condoms, cockroaches, cigarette butts, sanitary napkins and, as always, a steady supply of undigested corn kernels. The sewage - noxious and olive-colored - next goes to primary clarifiers. The 1 million-gallon, 105-foot-wide tanks let human waste and other heavy particles settle to the bottom. That sludge is pumped to thickeners and digesters that turn it into fertilizer for nonedible crops. On the clarifier's surface, a rotating rake skims off the scum that floats to the top. The sewage, already much clearer, is pumped to the top of 60-foot biotowers, where it seeps through a honeycomblike structure teeming with bacteria that "eat" waste. Then it's on to another round of clarifiers. By now the water is blue and hardly smells. The final step is disinfection. A healthy dose of chlorine is added to kill more pathogens as the effluent meanders through a mazelike basin. At this point, the effluent can take one of two paths. In summer, Tucson Water takes around half, treats it further, then feeds it into its reclaimed-water system, which waters grass at more than 600 locations, including parks, schools and golf courses. The rest is dumped into the otherwise dry Santa Cruz River. The effluent is still not drinkable because some viruses and pathogens are left, as are pharmaceuticals and high levels of nitrogen. The planned effluent plant would further purify the sewage and pipe it to Avra Valley, west of the Tucson Mountains, so it could seep into the earth and mix with groundwater before being extracted and delivered to your home. An emerging technology

Water-treatment technology is evolving rapidly, so Tucson Water has only a rough idea how it would further cleanse its effluent. If the plant were built today, effluent would be forced through a series of filters, membranes and activated carbon to remove contaminants. "It would be the best water we have. There would be no comparison," said Tim Thomure, senior hydrologist at Tucson Water. The utility's preference would be to build the facility at Roger Road and run a 42-inch pipe uphill from the smaller, more modern Ina Road sewer plant so it can tap that supply. An effluent plant able to process 41 million gallons a day would cost $278 million in today's dollars. Nearly half the construction cost would be for evaporation ponds for the reject stream of brine coming out of the reverse-osmosis step, when water molecules are forced through membranes and minerals are trapped behind. The ponds could claim hundreds of acres of city property in Avra Valley. The salts left over would have to be disposed of, possibly in a special landfill. Using today's engineering, some 15 percent of the water passing through a reverse-osmosis plant is lost to the reject stream - a major drawback for both effluent and salinity treatment systems. But Tucson Water officials say they're exploring cutting-edge technologies that might reduce water loss to just 1 percent, or allow them to sell minerals left behind and recoup some of their costs. The world's largest effluent- reuse system is under construction in Southern California. The Orange County Water District's $487 million project is to be running by 2007 and meet the needs of 144,000 families. Using microfiltration, reverse osmosis, ultraviolet light and hydrogen peroxide, the process is expected to cost 1.5 cents per 100 gallons. That's a bit less than the district would pay to import water from the Colorado River or Northern California, and two to five times less expensive than desalinating ocean water. Orange County rolled out its proposal a decade before construction began and "public perception was always a challenge," said Ron Wildermuth, the water district's director of communications. "It's got to be done face-to-face," Wildermuth said of convincing the public. "No amount of throwing paper around or advertising or things like that will work." A survey conducted in Tucson in 2000 suggests most residents here already dislike city water enough to seek alternatives. University of Arizona researchers polled 1,183 Tucsonans and found about one-third drink bottled water, one-third filter their water and one-third drink straight from the tap. Still, of the 130 gallons Arizonans use per person, per day, only 1.5 gallons is for drinking and cooking, UA researchers estimate. In summer, more than 60 percent of Tucsonans' water use goes toward irrigation. Is it safe?

Although water experts believe they could make effluent cleaner than any water delivered today, some challenges remain. Disinfection of drinking water now involves killing two types of disease-causing bugs: the giardia parasite and fecal viruses. "That works very well for groundwater and surface water," said Wendell Ela, a professor in the UA's Department of Chemical and Environmental Engineering. "But that's certainly not the case for wastewater." Porcelain bowls in which we excrete our wastes are just one of the unsavory sources of wastewater. Businesses also dump stuff down the drain, and only some are regulated in what they can discharge. "Hospitals do very little pre-treatment. Everything goes to the sewer," said Paul Blowers, a UA chemical engineer who has studied hospitals' water use. A hospital may discharge X-ray fluids with potentially toxic heavy metals, mildly radioactive isotopes used in chemotherapy, plus remnants of prescription drugs in patients' urine. Hospitals, therefore, would be a likely place to focus preliminary treatment before their sewage is mixed with the entire city's supply, Blowers said. Outside hospital walls, anyone taking medicines can excrete them into the wastewater system. And other chemicals - from fragrances to insect repellents to flame retardants - also go down the drain. So when U.S. Geological Survey researchers tested water downstream of sewer plants in 1999 and 2000, they were hardly surprised to detect all those chemicals, plus caffeine, sunscreen and birth-control hormones. Downstream of the Roger Road and Ina Road plants, scientists found 40 such chemicals in the Santa Cruz River - far higher than the national median of seven. That was expected because effluent dumped in the river isn't diluted by natural flow. The trace chemicals have only recently garnered the attention of scientists because they're measured in parts per billion or trillion. Instruments previously couldn't detect such low concentrations. "We don't have any information on their health effects. Maybe there are none," said Cordy, senior hydrologist with the geological survey in Tucson. Only 15 percent of the chemicals the geological survey analyzed have any health standards. And the 140 compounds the agency's lab can spot are just a sliver of the chemicals we're exposed to. "There are thousands of compounds we use in our daily lives and in our environment that are probably making it to the water. We're not even looking at those," Cordy said. Many of the trace chemicals already are found in the Colorado River, which supplies water to 25 million people. But U.S. Geological Survey scientists detected none of the compounds they were screening for in water arriving in Tucson via the Central Arizona Project, a 336-mile concrete river that pumps water uphill from Lake Havasu to Phoenix and Tucson. That's probably because the chemicals had been degraded, diluted or absorbed along the way. Salinity on the rise

What does arrive in Tucson via the CAP canal is plenty of salts and minerals. At its headwaters in the Rockies, the Colorado River may have a salinity as low as 50 parts per million of total dissolved solids. By comparison, the ocean's salinity is about 35,000 parts per million. But as the river passes salt springs and is continually reused on crops, it picks up more minerals - 600 parts per million by the time the river enters the Central Arizona Project canal. The CAP water is diluted in Avra Valley, where it mixes with local groundwater. But in five years or so, as more CAP water is used, Tucson Water will be delivering water with about 450 parts per million of total dissolved solids. That's the level at which many Tucsonans start to dislike the taste, according to tests the utility conducted in the late 1990s. Left unchecked, the CAP blend will level off at about 550 parts per million in a decade or so. That's 50 parts per million above the Environmental Protection Agency's nonenforceable guideline. But that mineral content is less than what many in the Southwest are already drinking. A special plant could suck much of that salt from our future water supply, but it would cost about a quarter of a billion dollars. If Tucsonans reject that - Tucson Water says we'll have to decide by next year - residents may have to buy in-home water-treatment systems to improve taste and protect appliances. Water bills set to soar

Coping with salinity and making effluent potable are destined to boost water rates already under pressure due to competition for water rights and leases, experts agree. Tucson Water plans to pre-sent the trade-offs this fall in a public-education campaign. Tucsonans will be able to taste water with different mineral contents and get a sense of what each formulation will mean for their pocketbooks. The utility wants to settle on an effluent plan by 2014, but the need to tap that supply could be pushed back by years, even decades, if Tucsonans cut their water use. Tucson Water's 50-year plan assumes no change in per-capita water consumption. Single-family homes here use an average of 120 gallons per person, per day - less than most other Southwest cities and 45 gallons below Phoenix's rate. The status quo for conservation may be a reasonable planning assumption, but it shouldn't be read as a prophecy, said Priscilla Robinson, a retired consultant active in Tucson water issues since the 1970s. "I can't believe there isn't more to be gained by a really fresh look at how we use water," she said. The 50-year plan shows that as a city must acquire new supplies, the next bucket is invariably more expensive than the last, she said. "Conservation is the cheapest source of new water, and that's a fact," she said. For now, water is the smallest utility bill for most Tucsonans. But gone are the days when people had to pay only for the cost of sucking groundwater to the surface and piping it to homes. Through water bills and taxes, residents already are helping pay for the $4 billion CAP so they can tap the Colorado River. And now they're poised to pay more to make effluent drinkable, CAP water less salty and to secure water rights from farms and tribes. Whatever course the city follows, it will lead to a future where we pay more for the water we use. "The cheap and easy option of the past," says Ralph Marra, Tucson Water's chief hydrologist, "is basically going away."