A poll of 2,000 adults found a quarter have showers for longer than 10 minutes each time, while 45 per cent don’t turn the taps off when brushing their teeth.
Nearly a third admitted to knowingly wasting water, with 29 per cent letting the tap run before it reaches the desired temperature.
And 29 per cent even flush the toilet unnecessarily.
It also emerged three in 10 think their partner is the worst for using water unnecessarily at home, but a quarter admit they are the ones who do this most often.
The research was commissioned by the Finish and WWF partnership, which has created the Journey of Water campaign to raise awareness of where freshwater comes from and how small, simple steps to save water at home can make a big difference.
Conor Linstead, WWF spokesperson, said: “As the water we use at home in the UK either comes directly from natural freshwater habitats, or indirectly affects them, how we use it really matters.
“Many freshwater sources such as rivers, lakes and wetlands are already affected by unsustainable water use at home and the impact of climate change could put further strains on these habitats.”
Of the 25 per cent who believe it’s unlikely we’ll ever run out of water, half reckon it’s because of our country’s wet and rainy climate.
Other reasons include having enough water supplies (38 per cent) and the country never experiencing droughts (39 per cent).
The daily average household use in the UK is 143 litres - that's 33 litres more than the government target of 110 litres.
If action is not taken, to address the impact of climate change and increased demand for water. The Environment Agency has warned the UK could potentially face water shortages by 2050 if current trends continue.
It also emerged 36 per cent incorrectly believed a dishwasher wastes more water than hand washing, while one in six thought it used the same amount.
However, independent research has shown dishwashers can save 6,800L of water a year, while hand washing and not pre-rinsing dishes can save 1,000 litres.
The study, conducted via OnePoll, also found 38 per cent of the parents polled would become better with their water usage if their child raised concerns about it.
Nearly three in 10 adults wouldn't be confident explaining the water cycle and where the water in their home comes from.
However, for 54 per cent, having a better understanding would make them more appreciative of it and more likely to reduce how much they use at home.
It comes after a separate survey of 500 6-10-year-olds found 26 per cent of little ones believed household water comes from the sea, while 24 per cent think it gets delivered to their house.
Despite this, a third correctly said it comes from places such as reservoirs while 34 per cent rightly identified rivers, streams and lakes.
Following the findings, the campaign has launched Water Heroes: The Journey of Water - a story from children’s author Catherine Coe, which tells the tale of the Water Wizard as he takes three children on an adventure to discover the sources of freshwater.
Steph Lilley, general manager, UK&I, Reckitt said: “The Water Heroes story is designed to create a deeper understanding that the water in our taps has travelled hundreds of miles and supports precious UK wildlife.
"We hope that the story gives both children and their families a new way to learn about the importance of freshwater in our lives.”
Primary school children were also taken on an educational walk around a constructed wetland in East Anglia, where the Finish and WWF partnership will be replenishing 500 million litres of water.
TV presenter and author Simon Reeve, who went on the walk, said: “It is important children know where water at home comes from and that we are all mindful of its use so we can help protect freshwater environments.”
Take this quiz to find out about your own water-use habits at home
