Utility firms underestimating domestic water use in UK, say researchers

Issue date: 23 August 2017

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Utility companies and government in the UK are underestimating how much water customers use, a new university study suggests.

A study exploring the water consumption habits of more than 8,000 students in university halls of residence over the past four years has revealed that students are using as much as 180 litres of water every day. This figure is 30 litres higher than the widely-used industry estimate of 150 litres per day. A practical implication of the research is that water companies and government need to abandon the idea of the 'average consumer' because there are other variables at play.

The finding was made during a unique long term study which has seen student accommodation at the University of the West of England (UWE Bristol) acting as a laboratory for exploring the complexities of domestic water consumption.

Metering systems have been fitted to an entire student residence development at the university's Frenchay campus, allowing academics to receive water use data on an almost real-time basis. Some 1,900 first-year students - aggregated into groups of a dozen or more to protect privacy - have had their water consumption monitored every year since the project began in 2013, with analysts able to link water use patterns with detailed socio-demographic information on the student population. Sophisticated data segmentation techniques allow the researchers to explore particular water using behaviours, like dish-washing, without revealing personal information.

With water companies unable to conduct similar studies into consumption trends, UWE Bristol researchers are aiming to fill the knowledge gap by collecting reliable usage data for the first time as part of the largest repeatable science research project of its kind in Europe.

Professor Chad Staddon, who is leading the study, was initially surprised by the average per person per day water use figure discovered in the project.

He said: “The figure was higher than industry expectations despite our students living in accommodation which does not have associated green spaces or driveways, so water is not being consumed on gardening or washing cars.

“But there is a ready explanation - because the students live on campus and often prefer to study in their flats, water use does not fall off in the day as much as might be expected in more 'normal' residential communities with higher daytime vacancy rates.”

Fixture inefficiencies, such as leaky loos, are also part of the underlying cause of higher consumption.

Professor Staddon, an expert in Resource Economics and Policy, said the findings had implications for the water industry.

He said: “Our figures could be a better gauge of total per person per day use than the domestic measure currently used by industry. Our measure is more indicative of total daily use because most of the students use all their water in one place - at home.”

The research is also exploring differences in water use by gender and student origin. Academics found female students tend to use more water than males - a variation which can be explained by the extra water needed to wash longer hair - and that UK national students consumed less water than their international counterparts, though this is linked to the greater propensity of UK–origin students to go home at weekends and holidays.

Another element of the research is focussed on testing the effectiveness of interventions aimed at reducing water use. Researchers are testing whether 'hard' measures, such as low flow showerheads and aerating tap inserts, reduce consumption by 'forcing' users to use less, and if 'soft' measures such as a shower timers and campaigns to promote water conservation could have a sustainable effect.

Early findings of the study, which could extend to 2020 and beyond, produced mixed results.

Professor Staddon said: “The results so far suggest that hard measures simply reinforce lower water consumption without really affecting overall behaviour – those who want or need to consume more water usually find ways to do so, such as simply showering for longer.

“During this past academic year, we have been exploring the effects of water pressure on water consumption, based on the insight that pressure is sometimes as important as flow for end users. Research to date suggests students haven't noticed the pressure changes at all, and that water is being saved, but we will have to wait until later in 2017 for the full results.”

UWE Bristol is working with the local water company Bristol Water on the study, called Socio-cultural Drivers of Water Demand in Student Residential Accommodation.

Professor Staddon said: “The study is aimed at developing a better understanding of how much water people use, what sorts of hard and soft interventions work or don't work, and how policy can be designed to promote conservation. With population growth and climate change, there is a growing need to conserve water. Yet there is not enough data-driven science about how much water is being used and for what reasons. Water companies themselves can't undertake this sort of research.”

Patric Bulmer, Head of Water Resource and Environment at Bristol Water, said: “We are delighted to be working with UWE Bristol on this unique and innovative study. The initial results have been enlightening and are supporting our efforts to encourage customers to drink more water whilst wasting less. Water efficiency will only continue to grow in importance given the changes to climate and population – by working with UWE Bristol on this project we are pleased to be ahead of the curve by having access to the very latest data and valuable real insights.”

This work has been funded by the Lloyd's Register Foundation, a charitable foundation helping to protect life and property by supporting engineering-related education, public engagement and the application of research.

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