The Yuck Factor: The Psychology of Drinking Recycled Water

Using sewage to create drinking water, or recycled water is a controversial topic in many parts of the world, especially in places where drought has forced utilities to develop alternative sources of tap water. In 2006 the Australian city of Toowoomba faced an extreme water supply problem and held a referendum asking its citizens whether recycled water should be added to the potable supply. This referendum led to emotional outbursts, and the proposal was eventually rejected. Some commentators on this event referred to the so-called ‘yuck factor’, which is an emotional reaction of repugnance towards certain foods and medicines. This article explores a psychological mechanism that causes this response and provides some suggestions on how to effectively promote the idea of using sewage to create drinking water.

Brendan Walsh diving in a sea of human waste.
Brendan Walsh diving in a sea of human waste.

The importance of origin

From a marketing point of view, using treated sewage to create drinking water is a proposition that ‘s hard to sell to customers. The origin of water is the most important aspect of the marketing of water, a concept masterfully used by bottled water companies. The importance of the (perceived) source of water was illustrated in a study which investigated whether there is a difference in willingness to pay depending on the name of water service. The research found that customers had a higher willingness to pay for “recycled water” than for “treated wastewater”.1 Although the study indicates that there are differences in valuation based on the perceived origin of the water, no explanation was provided for this phenomenon.

The psychology of disgust

There is no rational reason to oppose using sewage to create tap water. Regardless of technology, the natural water cycle ensures that all sewage will eventually become fresh water and most likely will find its way to somebody’s tap. Human psychology is, however, more complicated than this simple rational line of thought.

Our deep-seated negative overall attitude towards faeces leads us to maintain a negative attitude towards anything that is related to it, including recycled water. Rationally speaking, this is a fallacy and known as the Wisdom of Repugnance, or the yuck factor.  People arguing against recycled water use a non-rational ‘appeal to disgust’. They believe that a natural negative response to something should be interpreted as evidence for the intrinsically dangerous character of that thing. Although this is not considered a rational argument, it is nevertheless valid because we cannot ignore our innate psychological drives.

The psychological mechanism at work is the well-known principle of classical conditioning, also known as the Pavlov Reflex. Our cultural surroundings largely condition our tastes. Psychologists have researched these issues in detail. Faeces are a universal disgust substance that is deeply seated within our psychological make-up. This disgust is, however, not innate—we develop this feeling of disgust through conditioning.2

Yuck Factor online laboratory

To better understand this mechanism, follow the instructions in the online lab test displayed below. Click on the Begin button on the right. No data will be collected in this test.

[swf: 800 600]

What we see in this experiment is that the context in which the bowl is placed influences the attractiveness of the soup. None of the changes to the soup did, however, rationally modify the soup in any way. This experiment is based on the same principle behind the idea to use a special spoon to serve food to your pet—there is no rational reason to do so, but the perception of disgust is strong enough to motivate people to buy special spoons for their pets.

This experiment can be repeated using different water scenarios: straight from a spring, from a treatment plant, sourced from sewerage, downstream of a sewerage treatment plant and so on. This type of research should be conducted as it would assist utilities to sell better the proposition of using purified sewerage as drinking water.

Marketing recycled water

Although repugnance is a deep-seated psychological mechanism, the precise nature of the disgust mechanism is culturally determined. Just because a psychological mechanism is at work does not mean that it is hard-wired in our brain. Classically conditioned responses can be extinguished and reprogrammed. This change can, however, not be achieved by appealing to reason, as some industry experts proclaim.3

The marketing of recycled water is a delicate art. The repugnance against faeces is too deeply seated to be extinguished by reason alone. The most effective advertising to change attitudes does not appeal to reason—don’t try to convince your customers by telling them how great your treatment plants are. The best analogies to this problem are anti-smoking or safe driving campaigns. The most effective campaigns are those that appeal to non-rational aspects of smoking or speeding.

Given the intense disgust related to sewerage, telling people that they should drink and shower in recycled water will immediately activate the Pavlovian disgust reflex. The most effective way to sell the idea of using sewerage to create potable is to increase the level of trust customers have in the organisation, using origin strategies. Don’t emphasise the sewerage aspect of the water or the high-tech treatment facilities—emphasise the natural water cycle by using emotive images of pristine water flows. Focusing on the non-rational aspects of water consumption will increase customers’ involvement with utilities and ultimately have a positive influence on their perceptions of quality and trust in the organisation.4

What do you think? How can we make using recycled water as potable water acceptable?


  1. Menegaki, A. N., Mellon, R. C., Vrentzou, A., Koumakis, G., & Tsagarakis, K. P. (2009). What’s in a name: Framing treated wastewater as recycled water increases willingness to use and willingness to pay. Journal of Economic Psychology, 30(3), 285–292. doi:10.1016/j.joep.2008.08.007.
  2. Rozin, P., Haidt, J., & McCauley, C.R. (2008). Disgust in M. Lewis, J.M. Haviland-Jones & L.F. Barrett (eds.), Handbook of emotions, 3rd ed. (pp. 755–776). New York: Guilford Press.
  3. Russell, S., & Lux, C. (2009). Getting over yuck: moving from psychological to cultural and sociotechnical analyses of responses to water recycling. Water Policy, 11(1), 21. doi:10.2166/wp.2009.007.
  4. Cohen (2000). Consumer involvement–driving up the cost. Consumer Policy Review, 10(4), 122–125; Espejel, Fandos & Flavián (2009). The influence of consumer involvement on quality signals perception: An empirical investigation in the food sector. British Food Journal, 111(11), 1212–1236.

2 thoughts on “The Yuck Factor: The Psychology of Drinking Recycled Water

  1. Pingback: California Gets Past the Yuck Factor With "Toilet To Tap" Water Recycling | I World New
  2. Pingback: Self Driving Simpsons - Geek Feed

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