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A matter of taste
Much has been mooted around reusing toilet water, but there has been some resistance to this innovation and the question often revolves around taste: Is there a difference in taste between toilet water and tap water? By Kim Kemp
In March 2018, Cooperative Governance and Traditional Affairs Minister Zweli Mkhize declared the prevailing water crisis affecting multiple South African provinces a state of national disaster. As the water crisis continues, recycling wastewater was suggested as the answer to augmenting municipal water scarcity, in combination with water from desalinisation plants and groundwater, via boreholes.
The picky consumers, however, have been quick to pick up on the‘ recycled’ aspect, even calling the technology‘ toilet to tap’— or worse.( I’ ll just leave that there and let the poet in you work it out.)
The truth is, it is difficult to taste the difference between fresh and recycled water, and results of a blind taste test suggest that it is unlikely.
Historically, research has centred mostly around the safety of water, with wastewater being treated using reverse osmosis. A preferred technology is called indirect potable reuse, or IDR, which reintroduces treated wastewater into groundwater supplies, where it is mixed into the drinking water system.
The research
The University of California, Riverside( UCR), included 143 people in a study to compare IDR-treated tap water with conventional tap water and commercially bottled water. The waters were offered in similar, unlabelled cups, making the participants‘ blind’ to the source of the fluid. The theory was that all three would score similarly, but interestingly, tap water was the least popular among the tasters, while recycled water and bottled water scored about the same. After tasting the water, participants ranked the samples’ taste from one to five, then also in categories including texture, temperature, smell, and colour. Factors that influence taste perception were weighted by the researchers.
One such factor is genetic, which determines differences in taste sensitivity. This degree of sensitivity was gauged using a tried-and-true measure: paper strips coated with the chemical phenylthiocarbomide, or PTC. Those who find the strip’ s taste bitter are considered to have elevated taste sensitivity.
Researchers also considered two personality traits that help determine water preference. These traits are referred to as‘ openness to experience’ and‘ neuroticism.’ The former is gauged by how receptive people are to novel and diverse experiences, while neuroticism refers to anxiety and insecurity.
While from the outset, researchers assumed the three waters would score equally, one in fact, emerged the least preferred.
“ The groundwater-based water was not as well liked as IDR or bottled water,” says Mary Gauvain, a professor of psychology at UC Riverside and co-author of the study.“ 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.”
The more nervous, anxious people in the study expressed the preference for IDR and bottled water, while also expressing more negativity about the more mineral-rich tap water. While people more open to new experiences found all three samples to be almost on a par. Another surprise was that twice as
many women were likely to prefer bottled water as men.
The researchers’ best guess: Women register higher‘ disgust reactions’ than men, which means their reactions to tastes they dislike are more extreme.( These disgust reactions will form the subject of the team’ s next research paper.)
In its conclusion, researchers suggest that favourable comparisons between reverse osmosis and bottled water may make consumers more open to drinking recycled wastewater. u
Aside from Harmon and Gauvain, researchers in the study include Isaac Arthur, who recently completed his undergraduate studies at UC Riverside; Drew Story, a graduate student at UC Riverside; and Z Reisz, who received his PhD at UC Riverside and is now at Santa Barbara City College. The research was supported by an Integrative Graduate Education and Research Traineeship, or IGERT, award from the National Science Foundation.
Source: www. health24. com: Lifestyle / Environmental-health / News / couldyou-taste-the-difference-betweentoilet-water-and-tap-water-20180403
Most people are disgusted at the thought of drinking water from waste.
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