Study shows more powerful showers can be better for environment

Enjoying a more powerful shower in the morning could actually help reduce your household’s carbon emissions, according to researchers.

Showers not only use lots of water but also carry a hefty carbon cost through the energy it takes to heat up the water for our daily wash.

Now a study has discovered more powerful showers actually allow us to achieve our showering goal more quickly, resulting in shorter showers – particularly if a timer is also used.

Environmental psychologist Professor Ian Walker has been examining the impact water pressure has on our habits alongside Dr Pablo Pereira-Doel, from the Institute of Sustainability at the University of Surrey and James Daly, Sustainability Manager at the University of Bristol.

Their findings have now been published in a briefing document on OFS Preprints, a site used by researchers to share new findings on timely issues before they have been peer-reviewed for publication in a journal.

For their study they put sensors in 290 showers around the University of Surrey campus and covertly tracked the length of showers for 39 weeks, gathering data from more than 86,000 individual showers.
They discovered the average shower was 6.7 minutes, median was 5.7 and half fell between 3.3 and 8.8 minutes. Knowing how long the water ran in each showering event, and what the water flow rate was allowed the team to reliably estimate how much water was consumed each time somebody showered.

Professor Walker, head of the School of Psychology, explained there was a clear negative relationship between water pressure and consumption.

He said: “For any given flow rate, more powerful showers seemed to use less water overall. So a lovely tingly shower might be ‘better’ for the environment than a weak dribble.

“This research suggests people turn the shower off when they have achieved a desired sensation, not just when they have completed a certain set of actions. This is a potentially important new insight.”

The sensors featured timers that started automatically when the water flow began. To see if the timers made a difference, half of the showers has the timer display hidden.

He added: “It looks like a big advantage of the timers is that they stop showers from gradually creeping longer and longer as the weeks go by.

“Putting the two effects together, we saw average water consumption shift from nearly 61 litres per shower (low pressure, no timer) to under 17 litres per shower (high pressure, timer and this is hot water, so that means potentially massive carbon savings.

“In just this experiment, those 290 showers burned through 4.4 million litres of hot water, and about 15 tonnes of CO2e. The energy involved is mind-boggling when you start to think what it’s like at a national scale.”