The savings would come in reduced gas and electricity bills from avoiding heating more water than needed.
The study also found that the State could save €50 per household per year on water supply and wastewater treatment services.
That would add up to €10m by 2030 on the new homes that are promised to be built by then alone.
It would also ease the pressure in areas where Uisce Éireann has warned it is becoming hard to build new homes because water supply is under strain.
All it would take is a one-time outlay by developers of €180 per home.
Engineers at Trinity College Dublin carried out the research for An Fóram Uisce, the national water advisory body, which is urging the Government to take water conservation more seriously.
The study shows that installing simple devices such as low-flush toilets and aerator taps and showers could cut average water usage per person from 110 litres a day to 90 litres or less.
Heating water is one of the domestic activities that uses the most power and the study calculated that a household of four people could cut their bills by €280 a year.
Professor John Gallagher, the report’s co-author, said the measures made sense from several perspectives.
“People are often told that investing in sustainability measures isn’t always cost effective, but these efficiency-based solutions would make a significant impact for both their pockets and the planet,” he said.
“Crucially, if the Government can deliver its ambition of 303,000 new homes by 2030, it will free up 2.2 million cubic meters of water [2.2 billion litres] annually to reduce potential limits on development, and cut approximately €9.7 million in state costs for water and wastewater services.”
The report acknowledges that retrofitting homes with water-saving devices may cost more, but says the benefits would still flow.
More substantial water-saving devices, such as rainwater harvesting systems, are also investigated.
They would cost around €3,000 to install, but could save another 30 litres per day by providing all the water needed for toilet flushing.
“It does present a solution for specific areas of the country to deliver significant water savings and support housing targets and thus economic growth,” the report says.
An Fóram Uisce has urged the Government to amend the building regulations to make installation of water saving devices mandatory in new buildings and to introduce incentives for installing them during retrofits.
The Department of Housing said in response: “While water sustainability systems are not mandatory, they are being used increasingly in homes and buildings.
“The department has ensured that good conservation standards are referenced in the building regulations and the accompanying technical guidance document.”
It added that a National Water Conservation Working Group – another An Fóram Uisce demand – was being established to advise on a future strategy for water conservation.
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