Why Shower Routines Make Some People Shower Twice as Long

A new study suggests that the reason one person spends twice as long showering as someone else is unlikely to be their age, gender or household size.

Instead, the key appears to be their shower routine.

Researchers installed small sensors in the showers of 319 German households for one winter. Across 40 days, the equipment recorded 8,550 individual showers.

Factors linked to longer showers

The sensors tracked the length of time water was running, the number of times it was switched off, and conditions in the bathroom.

Participants could not time themselves, as the display that would have revealed the count was concealed.

For 958 showers, researchers paired the sensor data with a follow-up survey in which participants reported their age, household arrangements and the products they used.

The University of Surrey team created a comprehensive model to identify what was associated with longer showers. It assessed 14 factors simultaneously, allowing each to be considered while the others remained constant.

How repeated shampoo use extends shower time

Shampoo use produced the strongest pattern. Showers involving two or more shampoo applications lasted around 27% longer than those with a single lather.

Put simply, one shampoo application took about five minutes, while two took roughly six and a half minutes. More than one in five hair-washing showers included a second 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,” said Dr. Pablo Pereira-Doel.

“Small routines such as applying shampoo twice or letting the water run while lathering can extend shower time far more than people realize.”

Why pausing the water may have the opposite effect

Switching off the water while applying soap might seem an obvious way to reduce consumption.

Showers with one pause were marginally shorter, although the difference was too small to be reliable.

However, showers with three or more pauses showed the reverse pattern. They were approximately 20% longer than showers with no pauses and 28% longer than those with one pause.

The researchers interpreted repeated pauses as an indication of a leisurely, unhurried shower rather than a water-conscious one.

The effects of soft water and age

Showers in areas with soft tap water were about 23% longer than those in hard-water locations.

Because soft water produces a richer lather, it may make spending time in the shower more enjoyable.

Younger and middle-aged adults spent the longest in the shower.

Those aged 18 to 29 showered around 29% longer than people over 50, while people in their 40s showered about 31% longer.

Other factors that lengthened showers

Water-saving showerheads are designed to lower consumption by reducing flow. Yet in the households studied, they appeared to have the opposite result.

Just 13% of showers used a fitted flow restrictor. These showers lasted an average of 5:51, compared with 4:38 where no restrictor was installed.

When water flow is reduced, people may remain under the shower for longer in order to feel equally clean or warm.

The researchers describe this as a rebound effect. It points to a similar issue with any measure that reduces flow without changing the underlying routine.

Products may reduce shower water waste

L’Oréal Research and Innovation and Ipsos, the market research company that recruited the households, supported the research.

This funding is relevant because the paper’s recommendations return to product design. Its findings indicate that altering products may matter as much as changing behaviour.

Single-use products, clearer instructions on quantities and prompts showing when washing is complete could all help to cut water waste during showers.

According to the study, rinsing shampoo from hair uses roughly 7.1 litres of heated water. Conditioner requires about 6.3 litres.

Designing around existing habits

As all showers were monitored during one cold period, the findings cannot reveal how routines change throughout the year.

Participants may also have altered their washing habits slightly because they knew a sensor had been fitted, although the extended monitoring period probably reduced that effect.

For the hair-washing group, the researchers studied one person from each household. This means the analysis did not capture how teenagers or younger children in the same homes showered.

Participants were not asked about stress, mood or feeling cold, each of which could independently prolong a shower. In addition, every household was in Germany, meaning the results may not apply elsewhere.

“If we want to reduce household water consumption, we need to design solutions that work with people’s habits rather than against them,” said Pereira-Doel.

“Behavioral nudges, smarter feedback devices and better product design could all play a role in helping people use less water without sacrificing comfort.”