9bn litres of water used by UK households every day

Britons inflate their energy bills by over-filling kettles, taking extra long showers and hand-washing crockery rather than using more energy-efficient dishwashers.

The findings have emerged from the biggest ever study of how Britons use water, using data supplied by 86,000 British households and commissioned by the Energy Saving Trust .

Showers are by far the biggest consumers of water in the home, consuming 25%, with toilets second at 22%. An average shower lasts seven-and-a-half minutes, yet cutting just a minute off that time would save British households £215 million on energy bills each year, the report said.

On average, Britons shower 4.4 times a week, and take 1.3 baths.

The study revealed that 22% of household water is used in the kitchen, with washing machines, dishwashers, kettles and taps all taking their share. Three-quarters of households still boil more water than they need – with overfilling costing £68 million a year, in aggregate.

The average British household washes dishes by hand ten times a week, and only uses the dishwasher three times a week. But larger households could actually make greater energy and water savings by using an efficient, modern dishwasher rather than washing by hand, says the Trust. Households use their washing machine on average 4.5 times each week, yet only a quarter choose to wash at 30C or less.

Andrew Tucker, water strategy manager at Energy Saving Trust, said:

"When people think of energy use they think of heating and lighting, running electrical appliances or filling the car with petrol. It's all too easy to turn on the tap and not think about the consequences. But there is an environmental and energy cost attached to water which many people do not consider."