IT'S common knowledge a shower uses much less water than a bath, and a quick rinse over an long soak is a badge of honour for eco-warriors. The snag is, this isn't necessarily true.
Research into the habits of families has found that some showers use nearly twice as much water as the average bath.
While an average eight-minute shower uses about 62 litres of water, compared with 80 litres in the average bath, some power showers can use up to 136 litres of water -- comparable to 200,000 litres of hot water per year for a four-person family, at a cost of ¤1,064.
Unilever, which conducted the study of 2,600 showers in 100 households, said it was the first of its kind to accurately measure water usage. The findings threaten to debunk the "eco-myth" that a shower is always the greenest option.
"Showers are an increasingly large part of the mix in terms of the amount of water we use," said Jacob Tompkins, managing director of pressure group Waterwise, which campaigns for water efficiency.
He said the energy associated with heating water in the home is a significant part of co2 emissions and of our energy bills."
He added that while most showers still represent a more economical option than having a bath, some high-pressure power showers, which represent around 20pc of the market, did use more water.
The average person uses 150 litres of tap water per day, up by around 30 litres since the 1970s.
"Saving water is everyone's responsibility and it is clear from this research that by spending less time in the shower we can not only help the environment but also save money," said a spokesman for the British government's Department for Environment, Food and Rural Affairs.
Alternatives to high-pressure power showers include aerated shower heads, which mix air with water to reduce usage by up to 60pc and optimised showers, which regulate the flow across the shower head.
"While we'd still recommend switching from baths to showers, we suggest not to switch to a massive shower with a pump on," Mr Tompkins said. "Also, if people can cut down on their shower time, that has an impact."