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Small decisions made in the shower, from how often people wash their hair to the way they use water while showering, may have a bigger impact on household water consumption than previously thought, according to a new study.
Researchers found that shower routines, such as applying shampoo multiple times, were more strongly linked to longer showers than factors like age, gender or household characteristics.
According to the study, published in the Journal of Environmental Management, showers account for between 25 percent and 45 percent of indoor household water use, making them the largest contributor to water consumption inside the home.
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To investigate the issue, the team monitored showering behavior in 319 German households. Smart sensors installed in bathrooms recorded 8,550 shower events over a 40-day period, tracking factors including shower duration, pauses in water flow and environmental conditions. The data were then combined with post-shower surveys that collected information about demographics, hair characteristics and product use.
The researchers found that behaviors inside the shower had a significant influence on shower length.
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One of the clearest patterns involved shampoo use. Showers in which participants applied shampoo two or more times lasted around 27 percent longer than showers involving a single application.
"It turns out the biggest drivers of water use are not who you are or where you live. What matters most is what you actually do in the shower," study co-author Dr. Pablo Pereira-Doel, a fellow at the Institute for Sustainability at the University of Surrey, said in a statement. "Small routines such as applying shampoo twice or letting the water run while lathering can extend shower time far more than people realize."
The study also found a connection between water-flow interruptions and longer showers. Participants who paused the water three or more times during a shower spent around 20 percent longer showering than those who never paused the flow. When compared with people who paused the water only once, shower duration was approximately 28 percent longer.
Pereira-Doel told Newsweek that the researchers measured only the time water was actually running, not the total time people spent in the shower. He said a single pause to lather was different from repeatedly stopping and starting the water, which likely reflected longer and more elaborate routines involving activities such as shaving, conditioning treatments or the use of multiple personal care products that each require rinsing.
Age also appeared to play a role. Younger and middle-aged adults generally spent longer in the shower than people over the age of 50, according to the analysis.
One finding Pereira-Doel said stood out was that the age group often considered the most environmentally engaged tended to take the longest showers. He suggested this may be because showering is rarely viewed as an environmental behavior, unlike actions such as recycling or reducing air travel, and because people receive very little feedback about how much water they are using while they shower.
Another factor associated with shower duration was water hardness. The researchers found that showers in regions with soft water lasted around 23 percent longer than those in areas with hard water.
The team suggested that this may be because soft water produces a richer lather and creates a more comfortable washing experience, potentially encouraging people to spend more time under the shower.
The average American shower lasts for about eight minutes, using roughly 16 gallons of water, according to EPA.
While efforts to cut household water demand have largely focused on technological solutions, such as efficient showerheads, or economic measures, researchers argue that examining what people actually do while showering and addressing these behaviors may be a more effective strategy.
Potential approaches highlighted by the researchers include encouraging single shampoo applications and reminding people to switch off the water while lathering. They also suggest that behavioral nudges, feedback devices and product design changes could help reduce water use without requiring people to sacrifice comfort.
"If we want to reduce household water consumption, we need to design solutions that work with people's habits rather than against them," Pereira-Doel said. "Behavioral nudges, smarter feedback devices and better product design could all play a role in helping people use less water without sacrificing comfort."
The study's central conclusion is that seemingly minor actions in the shower can have a measurable effect on water use.
While technologies designed to conserve water remain important, the researchers suggest that understanding daily habits may be just as critical for reducing household consumption.
According to Pereira-Doel there's a real difference between technology that constrains the shower and technology that informs it.
“Restricting flow gives people something to work around, whereas showing them what they're using gives them something to act on. If a device makes the shower less satisfying, people may simply stay in longer to compensate, and the saving evaporates, or reject the device completely,” he said.
Reference:
David Morizet et al, Event-level modelling of showering behaviour in German households: Triangulating smart-meter, in-situ survey and contextual public data, Journal of Environmental Management (2026). DOI: 10.1016/j.jenvman.2026.130596
Contact Newsweek editors on this story: Kara Dolman and Emma Lee-Sang
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