Recycled Toilet Water Aces Its Taste Test

Think you could taste the difference between recycled toilet water, bottled water or tap water?

It’s unlikely, results of a blind taste test suggest.

Years of drought in California have given momentum to household use of recycled wastewater. Six water agencies in the state already use wastewater that’s produced through a technology called indirect potable reuse (IDR), the University of California, Riverside, researchers noted.

The IDR approach redirects treated wastewater into groundwater supplies, where it re-enters the drinking water system.

Although research has shown that recycled wastewater is safe, people are often repulsed about things such as taste.

“It seems that this term [wastewater], and the idea of recycled water in general, evokes disgust reactions,” said study author Daniel Harmon, a graduate student in psychology.

“It is important to make recycled water less scary to people who are concerned about it, as it is an important source of water now and in the future,” Harmon said in a university news release

He and his colleagues asked 143 people to compare the taste of IDR tap water, conventional groundwater tap water and bottled water.

“The groundwater-based water was not as well liked as IDR or bottled water,” said study co-author Mary Gauvain, a professor of psychology.

“We think that happened because IDR and bottled water go through remarkably similar treatment processes, so they have low levels of the types of tastes people tend to dislike,” she said.

Looking at personality types, the researchers found that nervous and insecure people tended to prefer IDR and bottled water.

Also, folks who were more open to new experiences rated the three types of water about the same. And women were two times more likely to prefer bottled water than men.

“We think this research will help us find out what factors people pay attention to in their water decisions, and what populations need to be persuaded to drink IDR water and how to persuade them,” Harmon said.

The study was recently published in the journal Appetite.

More information

The U.S. Environmental Protection Agency has more on water recycling.