Three-quarters of people are not concerned about the amount of water they use in the home and less than a third think they could make savings, a poll suggests.
But people spend an average of nine minutes in the shower, well over the four-minute wash recommended by utilities to save water and cut bills, the survey of 3,000 adults for environmental charity Hubbub and supplier Affinity Water found.
The poll by Censuswide revealed only 31% said their household could use less water if needed.
But four out of 10 admitted to running the shower for at least a minute before getting in, using the time to clean their teeth, shave or go to the toilet, while some ran it long enough to do exercises or make a cuppa.
According to the survey, Londoners spent longest in the shower, averaging 11 minutes, while people in the north-east of England were speediest, with average washes of seven minutes.
Younger people appear to be more inclined to linger in the shower, with the 16 to 24 age group saying they spent 13 minutes on average, compared with seven minutes for over 55s.
Affinity Water and Hubbub are launching the #TapChat challenge to encourage people to make small changes to reduce their usage, as they warn water resources were below average.
According to the organisations, despite perceptions showers save water compared to baths a modern power shower can pump out an average 13 litres a minute, which means a six minute shower can use as much water as a bath.
They are suggesting measures to cut water and energy bills, including using a free shower timer from water suppliers, switching to a water-saving shower head and even capturing cold water from the start of a shower in a bowl to water plants.
Melissa Painter from Affinity Water said: "Despite the rainy summer, our water resources are still below average, so we are asking people to save water all year round, not just in the summer.
"Little changes can make a really big difference and with everyone's help now we can minimise the chance of water restrictions next year."
Trewin Restorick, chief executive and co-founder of Hubbub, said: "We're keen to show people how easy it is to make small changes that add up to make a big difference.
"If everyone in the UK cut their shower time by two minutes, we'd save eight billion litres of water a week.
"Using less water can save money too, even if you're not on a water meter, as shorter showers mean lower energy bills."