AUSTIN, TEXAS — Cleaned-up sewage is nobody’s first choice for drinking water.
But some parts of the world may not have much choice, especially if they have large or growing populations and limited fresh water. Parched communities from Singapore to the United States are coming to terms with the “toilet to tap” idea, aided by educational campaigns and careful marketing. (Do not call it “toilet to tap,” for starters.)
In Singapore, a wastewater-reuse plant has become a destination, drawing nearly a million visitors, including schoolchildren and curious tourists, since an educational center opened there in 2003. As much as 3 percent of Singapore’s drinking water comes from recycled water, which has been branded NEWater. Visitors to the center receive colorful bottles of the water at the end of their guided tours.
“Some of the NEWater bottles become collector items, especially the first batch,” said Harry Seah, the chief technology officer of PUB, Singapore’s national water agency, which plans to expand its capacity for recycled water further.
The majority of the public accepts the water, Mr. Seah said. The water gets cleansed with membranes and ultraviolet disinfection, and most of it goes to supply industry, like factories that need large quantities of highly purified water to operate. The portion that is slated for the taps gets blended with reservoir water and cleaned further before it is piped to households.
The technology for recycling wastewater for drinking has existed for decades.
One pioneer was Windhoek, Namibia, which began sending treated effluent into the potable water system in 1968 . (Windhoek will be host to a major conference on water reuse next year .) El Paso, Texas, has injected treated wastewater into an aquifer since 1985 ; after mingling with groundwater, it eventually gets pumped up for reuse as potable water. Similar American systems, especially one in Southern California that began operating in 1976 , helped inspire Singapore to go ahead with its larger-scale project, Mr. Seah said.
Of course, plenty of wastewater worldwide already gets recycled to a lesser standard for nonpotable uses, like watering lawns or golf courses. Projects that convert wastewater into drinkable water remain a novelty, but more are on the way .
In the United States, a $12 million plant in Big Spring, Texas, that is due to be completed at the end of the year is “the hottest topic of the day,” said Wade Miller, executive director of the Virginia-based WateReuse Association.
The facility will treat cleaned wastewater and contribute to the drinking water supply of several drought-stricken oil boomtowns in Texas, including Midland and Odessa.
Another water-recycling project is inching forward near Perth, Australia . The idea is to clean the wastewater, then pump it into an aquifer for eventual retrieval. (The Texas project, unusually, will not include an intermediate stage of sending the cleaned-up wastewater into an aquifer or reservoir.)
Water Corp., a water supplier in the state of Western Australia, is evaluating the facility near Perth, the state’s capital.
When the trial ends in December, Water Corp. officials expect to recommend expanding the project; they envision that it will eventually supply 10 percent of Perth’s potable water. Perth, like Singapore, is supplementing its water supplies with desalinated ocean water, but reusing wastewater is cheaper because removing the salt from seawater requires more energy than cleaning sewage to potable levels.
A big reason Water Corp. has proceeded cautiously on the Perth project is public acceptance. The ick factor has proved to be the most serious hurdle for similar projects around the world. Australia has recent experience with this: The Queensland city of Toowoomba ran into a perception problem in 2006 when, in the midst of a severe drought, it held a referendum on building a recycled-water facility. Groups like “Citizens Against Drinking Sewage” sprang into action, and the initiative failed .
To woo the public and avoid the “drinking sewage” stigma, Water Corp. opened a visitor center in 2010. The center, like Singapore’s, explains the treatment process and the region’s water needs. Officials are finding that greater knowledge brings greater acceptance.
“We can take just about any source of water and apply appropriate technology and make it drinking water,” said Linda Macpherson, a water-reuse specialist with the construction and design firm CH2M Hill who has worked on the Perth and Singapore visitor centers. “What we don’t have is an understanding in our minds that this can happen.”
For projects worldwide, a key to improving that understanding is how the reused water is described. “Wastewater” or “reclaimed” water and, of course, “sewage,” make the technology’s proponents cringe. “Recycled water” sounds better.
But why even mention where it came from? The Perth facility describes its purpose as “groundwater replenishment,” which emphasizes where the water is going. Singapore’s NEWater sounds new. The Texas plant is called a “raw water” facility.
The challenge is humorously depicted in the documentary film “Last Call at the Oasis,” which is about the world’s water problems. Jack Black, the Hollywood actor, is called upon to drink from a futuristic (and fictitious) bottle of “Porcelain Springs” water.
“Don’t think sewer. Recycled. It’s recycled. This is pure, natural, regular water,” the actortells himself before taking a drink.
Ultimately, of course, everybody participates in the “toilet to tap” concept, whatever the terminology of choice. Even without expensive recycling plants, water from one city’s toilets is eventually going to end up downstream in another city’s taps. It is just a matter of time.
“All water,” Ms. Macpherson notes, “is used and reused.”