Press "Enter" to skip to content

‘Toilet to tap’ water nearly matches bottled H20 in taste test, university researchers discover

Saddled with the “toilet to tap” label, recycled water still has a bit of an image problem. But in a blind taste test, UC Riverside researchers found that people prefer its flavor over tap water and that they like it as much as bottled water.
Intuitively, that may sound crazy. But it makes sense, suggests UCR’s Daniel Harmon, lead author on a recent study analyzing the taste test published recently in the journal Appetite.
“Bottled water and recycled water go through more or less identical purification processes,” Harmon said. Both, experts said, are subjected to reverse osmosis, which removes most contaminants.
The study is encouraging, water officials say, because it comes at a time when Southern California is having to rely increasingly more on recycled water, and not just for turf and crop irrigation. As the planet warms, droughts become more severe and water supplies shrink. It also comes as state officials are expanding the ways agencies can filter recycled water and add it to drinking supplies. UCR’s research may help set the stage for one day piping it directly into drinking-water systems.
UC Riverside researcher  and study lead author Daniel Harmon holds up clear plastic cups of drinking-water samples at the Riverside campus on Tuesday, Aug. 14, to demonstrate how his team conducted an experiment to see whether participants — college students between the ages of 18 and 28 — could tell the difference between recycled, tap and commercial bottled water in a blind taste test. (Photo by Watchara Phomicinda, The Press-Enterprise/SCNG)
“It’s inevitable that we’re going to have to use this resource more and more,” said Harmon, a doctoral candidate in development psychology at UCR.
Kevin Pearson, a spokesman for Eastern Municipal Water District, which supplies drinking water to more than 800,000 people in Riverside County, termed the results encouraging.
“This goes to show that people are willing to use this as a water source,”  Pearson said.
What Harmon’s team did was bring in 143 UCR students ranging in age from 18 to 28, one at a time.
“We wanted to figure out whether people could tell the difference between recycled water, tap water and commercial bottled water,” Harmon said. “They were presented with three clear cups labeled A, B and C. They were completely blind to the source of any water.”
After tasting the water, participants rated samples on a scale of one to five — one indicating strong dislike and five a strong like for. Harmon said bottled water received the highest score at 3.79, but recycled water nearly matched it at 3.77. The groundwater-based tap water sample scored 3.45.
“We were surprised that the groundwater was less liked,” he said.
A man pours a glass of fresh water from a kitchen faucet. (Photo courtesy of UC Riverside)
Harmon said researchers also evaluated personalities and analyzed whether that factored into preferences. Their conclusion? It did.
They found that people who are open to new experiences tended to like the three samples the same. But people who are more nervous or anxious preferred bottled water, Harmon said.
“What we learned is, purity and freshness is king in water preference,” he said.
Harmon said the taste test was conducted in 2015, but the study was published this year. Researchers are considering a follow-up study, he said, saying he could not hint what that might entail.
The implications are huge. The state is moving toward more extensive reuse of the waste water that flows through our sewer lines. It’s already an important part of our supply.
In Southern California, the region consumes 3.5 million acre-feet of water annually. And, of that, the source of 460,000 acre-feet is recycled waste water, said Deven Upadhyay, Metropolitan Water District assistant general manager and chief operating officer.
“It’s been on an uptick for years,” he said.
A common measuring unit in the water world, an acre-foot is about 325,000 gallons or what would cover an acre one foot deep. It’s what three Southern California families use during the course of a year.
Upadhyay said some recycled water irrigates parks, golf courses and sport fields. Some is used by industry. And some is used for drinking, showering and washing dishes.
Orange County residents are already doing the latter — on a large scale.
Orange County Water District, in partnership with the Orange County Sanitation District, just celebrated its 10th anniversary of operating the world’s largest recycled-water plant. It generates 100 million gallons of fresh water daily from waste water, said Denis Bilodeau, district president. And his agency is expanding the plant.
Orange County Water District officials were so confident in the purity of their recycled waste water that they handed out bottles of it in Hollywood in March 2017. (Photo courtesy of Orange County Water District)
The purified sewer water represents 30 percent of all water produced by the water district for residents of northern and central Orange County, Bilodeau said.
It’s injected into the ground.
“It goes through several hundred feet of sand and soil,” where it is subjected to additional filtration, he said. “And eventually it is taken up through drinking water wells.”
A similar plant is coming to Los Angeles County. Upadhyay said Metropolitan is partnering with the Sanitation Districts of Los Angeles County on a demonstration project that will be completed in 2019 and serve as a precursor to a large-scale operation.
Taking the process a step further, the San Diego area is preparing to add recycled water to a reservoir. The State Water Resources Control Board cleared the way for that through a roll-out of regulations in March.
By 2023, the board anticipates unveiling rules that would set the stage for piping recycled water directly into drinking systems.
George Tchobanoglous, a retired UC Davis professor of civil and environmental engineering who recently served on statewide expert water panel, said it may be 10 years before that level of recycling arrives.
“I think that’s a ways off,” he said.
Tchobanoglous said some issues likely will have to be resolved and officials will have to secure the public’s confidence. It’s unfortunate, he said, that a number of years ago someone popularized the phrase “toilet to tap.”
But, he said, “It is inevitable.”
He said direct piping of recycled water into homes is done in several water-starved places around the globe now. One such example is South Africa.
One can also look to the stars to find an example. At the International Space Station, Bilodeau said, every drop is captured. “Even the perspiration is recycled.”
“This isn’t a science fiction thing,” he said. “It already occurs.”
Source: OC Register

Be First to Comment

Leave a Reply

Your email address will not be published. Required fields are marked *