It also finds 65% are making "a concerted effort" to change their behaviour
New research has claimed that over 50% of Irish people surveyed under-estimate average daily personal water usage by half.
The findings, from Irish Water, come as the utility launches a public information campaign on the importance of continuing to conserve water.
The campaign - which will be seen across online, radio, TV, in newspapers and outdoor over the coming weeks - also offers tips and advice on how to conserve water.
It says the average person uses 129 litres of water a day.
However the research indicates that 56% of those surveyed believe that the average person uses less than 50 litres of water per day - 20% believe they use between 51 and 100 litres, 14% estimate that it is between 101 and 200 litres and 10% believe it is over 200 litres.
The research - among 1,000 adults - was conducted by Behaviour & Attitudes (B&A) between July 11th and 19th on public water usage and attitudes.
The B&A survey also shows that 65% of people have begun to make "a concerted effort" to change their behaviour to conserve water.
Irish Water's corporate affairs manager, Kate Gannon, said: "Conserving water is a new conversation for many people but an important one.
"The recent period of drought has shown that the demand on Ireland's water supply can impact homes and businesses across the country.
"Irish Water wants to support people in their choices around their water use; beginning by showing people how much they actually use.
"The fact that 65% of people have started to make a concerted effort to conserve water since the beginning of the drought is really encouraging but to see real and positive effects, we hope to see long term and permanent changes to the way we all use water.
"The majority of those surveyed say that recent communications have made them think and act differently regarding their water usage and conservation."
Irish Water has launched a new water conservation information campaign for August. The hosepipe ban is in place until end of the month. ‘Don’t rush to flush’ - their top tips are also on their website https://t.co/erpwRyAnr3 pic.twitter.com/hqUW7YHBw7— Gail Conway (@Gailiana) August 2, 2018