Leaky toilets the biggest problem, according to engineers
Irish Water say data from their newly installed metres show that the average Irish household is using about half the water previous indicated by previous estimates.
Leaky toilets, meanwhile, cause the most water wastage in Irish homes, according to a senior engineer with Irish Water.
Kate Gannon, a conservation specialist with the controversial semi-state company, also said new measures introduced by Irish water have saved 34 million litres every day - enough to service the entire water needs of County Wicklow.
"It had been estimated homes could be using up to 190 litres per person per day," she told the Pat Kenny Show on Newstalk.
"But it has emerged that 93% of households are only using about 250 litres per day, or just over 80 litres per person.
"This shows the level of uncertainty around how much water people used, and therefore, how much water was being leaked across the water network."
The future of Irish Water is shaping up as one of the key issues in the formation of the next Government, with Fianna Fáil seeking to scrap the controversial utility in their talks with Fine Gael.
Irish Water say leaks remain an enormous problem on the wider water network, with an average of 47% of water being produced nationally disappearing into the ground through leaks.
In Co Cork, 57% of drinking water produced is disappearing in leaks.
In Roscommon it stands at 68%.
In Mayo, 58% is lost, and in Dún Laoghaire, it stands at 50%.
"In our earlier days, we found that up to 50% of leaks were actually inside the home," Ms Gannon added.
"A running toilet was the biggest one, actually. If you have the back toilet or the toilet under the stairs, and there's a little bit of toilet trickling down, that could be it."
"Historically, leakage was quite difficult to estimate, as we did not know how much water was being used by houses on a day to day basis," Ms Gannon added.
"To try to estimate usage, an estimate was used per person. The average for this figure in Ireland was 150 litres per person per day - and older international studies from 10 years ago even thought it could be as high as 190 litres per person, per day.
"We now know that the national average of all houses in Ireland is 350 litres per property per day, but about 7% of these houses have significant leaks and use up to 1500 litres per day, which we are targeting through our first fix programme, which gives a free repair to customers for leaks under their driveway."
Ms Gannon said that leaks fixed to date have saved 34 million litres per day - enough water to supply entire county of Wicklow for a day.
"This new technology and meter data is helping us to tackle leakage and inform our investment plans into the future, such as the first fix programme, leak detection and repair on public networks and pipe replacement across the country.
According to Irish Water, 7% of domestic customers have significant problems with leaking pipes and are using an average of 1,500 litres of water per day - nearly eight times more than the average household.
"There is one old house that we came across in Ringsend in Dublin that was leaking enough water to supply a big town," added Gannon.
"We want to reduce leakage to a national average of 38% by 2021. By reducing it by 1% to 2% per year, this will conserve about 30m litres of water a day, which is equal to the water needs of Wicklow," said Ms Gannon.
She added that the aim was to save enough to supply County Wicklow for a year.