A survey, using innovative technology, has offered an insight into people's showering habits.
The average shower lasted eight minutes - much longer than previous studies suggested, using almost as much water and energy as the average bath.
The information was compiled from "data loggers" that recorded 2,600 showers by 100 families over a 10-day period.
The survey was carried out by producer Unilever, which wanted to find out how people were using their products.
According to the data, an eight-minute shower used 62 litres of hot water, compared with an average bath's 80 litres.
And, it suggested, that if people were using a power shower - an appliance that adds extra pressure to the water flow - then an eight-minute shower would require twice as much water and energy as a bath.
Hilde Hendrickx, a behavioural scientist in Unilever's R&D department, said that the company decided to carry out the survey because "quite a large proportion of our (products') environmental impact occurred when people used them".
Referring to shower and bath products, she added: "We know that 95% of the associated greenhouse gas emissions are related to people [using] our products because they have to use hot water."
Previously, data on showering behaviour had been collated by asking households to complete questionnaires. But this approach had a number of drawbacks, Dr Hendrickx explained.
"The problem with that is that people do not often have a very good insight into their behaviour because it is a habit and they may not be very aware of what they are actually doing," she told BBC News.
"When it comes to time perception, most people are not very good at estimating at how long it took them to do a particular activity."
Hence the need to find a different way to record it, she said, but the challenge was getting reliable data on a private activity.
"People would not take too kindly to someone standing next to them with a clipboard."
In order to overcome this, the company's R&D department developed a data logger that they called a "shower sensor".
"It is based on acoustics and temperature, so it basically picks up the noise of the water as it runs through the pipe," Dr Hendrickx explained. "It also picks up the change in temperature."
She added that by using algorithms, researchers were able to extract the necessary information about people's showering behaviour from the raw data.
The findings, she said, challenged some long-standing assumptions, such as people showered, on average, for five minutes.
Paula Owen, an independent environmental consultant, said the survey gave a "fascinating peek into the bathroom-related habits of the British public".
"Most people have now got the message that, generally, taking a shower is more environmentally friendly than a bath, but what this research shows is this is not necessarily the case," she told BBC News.
Dr Owen, who produced "eco action trump" cards to help people understand the environmental and economic impact of everyday activities, said that she recommended that people took four-minute showers.
"Unfortunately it seems that message is not getting through," she said.
"The results here show that the average time spent in a shower is double that. This wastes not only water, but also the energy needed for heating the water too.
"People always consider the running costs of cars and phones, but no-one considers the running costs of everyday appliances such as showers, washing machines and TVs."
The survey suggested that taking eight-minutes showers would cost an average UK family £416 a year; using a power shower would see the annual bill soar to £918.
But Dr Owen said there were a number of options available to people who wanted to cut their water and energy bills.
"Water companies often give away timers that help you limit your time in the shower and attachments are available to fix to your shower head that will reduce the flow but not the bathing experience," she explained.
"If you are partial to singing in the shower, pick a short pop classic to shower to; and when lathering up think about turning the flow off until you are ready to rinse."
Dr Hendrickx acknowledged that the survey was not representative of the entire nation, but added that there were plans to conduct more surveys in the future.