Just 3pc of a fund set up to help homeowners replace toxic lead pipes has been used over the past five years.
Of €9m allocated to the grant scheme run by councils since 2016, only €264,292 has been drawn down. Only 105 households have availed of the scheme out of the tens of thousands believed to have lead pipes in their homes.
Sinn Féin housing spokesman Eoin Ó Broin, who obtained the figures, said the scheme needed to be reviewed urgently to see if eligibility criteria, limits on grant values or other issues were responsible for the low take-up.
"The vast majority of people may not even know the scheme exists," he said.
"But whatever the issues are, the health implications are far greater than the lacklustre way the problem is being pursued by the Government."
Lead pipes were installed in houses and buildings up to 1980 and Irish Water estimates they may be in 180,000 homes.
The metal can leach into the water it carries and cause serious health problems over time, including developmental delay in children and infertility, liver, kidney and neurological problems in adults.
Michelle Minihan, senior water inspector with the Environmental Protection Agency (EPA), said people probably did not appreciate the dangers.
"If there's a biological problem in your water, you'll get sick within a few days, but lead affects people over time so they don't see it in the same way and don't react with the same concern," she said.
"But the World Health Organisation and the Health Service Executive are very clear that there is no safe level of lead in drinking water."
Sean Giffney, chairman of the Association of Plumbing and Heating Contractors, also said awareness was low.
"The pipes are tucked away under the floor and out of mind," he said.
"When we come across lead pipes and tell people they need to do something about them, they think we're just trying to get extra work out of them.
"The other problem is the cost. The plumbing is only part of it. If people have to replace floor boards and tiles or part of their driveway, it all adds up."
The grant scheme allows a maximum payment of 80pc of the cost up to €4,000 but only for plumbing, not for associated works. Total household income must be below €50,000 to get the maximum grant. Households with income up to €75,000 can get 50pc of the cost up to €2,500. Households with income exceeding €75,000 are not eligible.
Irish Water only replaces lead pipes on public property. It won't replace a section connecting a house to a public water main unless the householder undertakes to replace the next section running through their property, as only a full replacement is effective.
Mr Ó Broin said all the bodies involved needed to sit down together to work out a better response.
"Government needs to decide if it actually wants to replace the pipes and, if it does, it needs to give this a lot more energy," he said.
The Department of Housing said the ESRI was carrying out a study on the issue for it.
"The study will contribute to informing the examination of ways to increase the rate of take-up of the grant in private properties and will form part of any future policy considerations," it said.