Recycled wastewater evokes disgust reactions

That's the result of a series of studies by UC Riverside psychology researchers Mary Gauvain and Daniel Harmon published recently in the journal Basic and Applied Social Psychology.

Past research by Harmon and Gauvain explored whether people sense a difference in taste among recycled water, conventional tap water, and commercially bottled water. That study, released in spring 2018, was based on a blind taste test and found people actually preferred the taste of recycled water over conventional tap water.

However, "The idea of recycled wastewater in general evokes disgust reactions," Harmon said at the time.

This idea was addressed in the psychologists' latest research. If people disgusted by the notion of recycled wastewater are educated on its safety and benefits, will their attitudes change? And, will they change their behaviors?

In the research paper, "disgust" is defined as "a strong repulsion to a potentially harmful substance." In addition to disgust, the research considered other factors that dissuade people from using recycled water. Those included misinformation, ignorance, and peoples' desire to conform to social norms.

The research involved three separate studies and a total of 886 participants.

In study one, half of the subjects viewed a brief, pro-conservation internet video. The other group watched a short video about water, but not conservation, about the urban myth that crocodiles live in the sewer system of New York City.

Researchers found both groups failed to budge in their willingness to endorse sustainable water. Ninety-six percent of participants cited disgust as the reason. Distilling the reasoning even more, the researchers asked if participants were motivated by cleanliness or fear of illness. Sixty-five percent said cleanliness.

In study two, the videos were used again. But this time, an educational video demonstrating recycled wastewater is contaminant-free was also shown to address the disgust reaction. The pro-conservation and disgust videos had a "small but unsubstantial effect on peoples' willingness to use recycled wastewater" the research found.

In the last study, participants viewed all three videos. But this time, after completing a post-video survey, they were offered a bottle of water labeled "SMARTdrop--Pure Recycled Water" and asked to sign a conservation petition.

Researchers hypothesized participants who watched the video addressing disgust would be more likely to accept the water and sign the petition. In fact, a similar number across all three groups -- about two-thirds -- took the water bottle and signed the petition.

The results of the three studies run counter to previous findings that assert media information can influence peoples' water conservation attitudes. Instead, they show internet messages may encourage people to view water sustainability more positively, but they do not encourage more sustainable water behaviors.

The article drawn from the research, "Influence of Internet-Based Messages and Personal Motivations on Water-Use Decisions," discourages using pro-recycled wastewater internet videos about water scarcity and conservation alone. Instead, researchers urge a focus on the more visceral roadblock of disgust. As an example, the researchers suggest a video stressing the extent of water purification in recycling plants as part of larger campaigns to change behaviors.

Disgust is an exceptionally robust motivation that may require stronger intervention to overcome."

Daniel Harmon, UC Riverside psychology researcher