Householders may have to spend up to €5,000 replacing lead pipes.
Irish Water will pay to replace the pipes outside properties but homeowners have to pay to strip out the lead piping inside.
The utility is warning people who live in homes built before 1980 to check for lead and says there is a Government grant available to help with the costs.
Irish Water will also publish a national plan to remove lead from our drinking water later today.
Mark McCauley of Irish Water says there is a simple way to check for lead.
He said: "Basically what you are looking for is, if you look under the kitchen sink typically you will find a kind of black-grey metal pipe and if you scratch it it will expose a silver undersurface.
"So that's a simple way of checking, but if there is any doubt, you should employ a plumber to check for sure."
The Irish Water managing director, Jerry Grant, said drinking water produced at the utility’s plants was lead-free, and all lead water mains in the distribution system had been replaced.
A programme to replace remaining lead service connectors, short pipes connecting the water main to property boundaries, has begun.
“The greatest risk remaining from lead in drinking water is, therefore, arising on private property from internal plumbing,” he said.
While full lead replacement was the best option, this had taken decades in other countries so the possibility of treating the water to reduce the risk was an option.
“A food-grade product called orthophosphate can be added to drinking water at our plants to coat old lead pipes in people’s homes and reduce exposure and consequent health risk until the pipes are replaced,” said Mr Grant.
He pointed out that orthophosphate was extensively used in Britain, Northern Ireland, and widely across North America.
However, Irish Water is legally obliged to consider the potential impact on the environment, and this would involve individual assessment for each Irish water supply.
“We are now asking members of the public to look at the plan and give us their feedback on our proposed approach. In the meantime, we are also asking all property owners, especially those with young children, to check for lead pipes and to have them replaced if at all possible,” said Mr Grant.
The Department of the Environment has established a grant scheme to assist low-income households in replacing lead pipes.
The public consultation on the draft plan will run from today until September 2. It can be viewed online at www.water.ie/lead and at local authority offices.
Irish Water is now testing 35,000 random samples of water quality annually, compared with 3,000 previously.
The utility estimates that about 180,000 homes and hundreds of commercial and public buildings still have lead plumbing, including lead service pipes from the water main to the stopcock.
Of the homes affected, about 40,000 are thought to have shared backyard (common service pipes) that Irish Water will be replacing over the next five years.