The water supply in up to 200,000 homes is in danger of lead contamination, in what has been described as a 'public health risk'.
The alarming scale of the problem was uncovered by Irish Water, which detected the poisonous metal in pipes in 200,000 of the country’s households.
Lead pipes were also found in schools and hospitals, with the problem believed to be particularly bad in Dublin.
But Irish Water today warned that dealing with lead that exists within domestic properties could cost €250m-€300m.
And the majority of individual households will have to foot the bill, which experts say could be in the region of €3,000.
Homeowners with lead plumbing are expected to receive grants of up to €4,000 to replace their pipes.
The grants will be closely modelled on the septic tank remediation scheme. It allows households with incomes up to €50,000 to receive 80pc of the costs back in the form of a grant, up to a maximum of €4,000.
Those earning between €50,001 and €75,000 can claim up to 50pc of the costs back, up to a maximum of €2,500.
The move comes as the cabinet this morning discusses the issue of lead piping in private homes, local authority housing, hospitals, schools, prisons and other public buildings.
Some 28,000 homeowners have been written to by Irish Water, notifying them of a potential issue with lead piping in their homes. However, as many as 200,000 are believed to have a problem.
The Cabinet is today discussing the details of a grant scheme that will be rolled out for families who are in low-icome brackets.
Government sources have warned, however, that the State will not cough up the required sum to clear the lead in all homes affected.
Dublin is of particular concern for Environment chiefs with homes on the Northside suffering from dangerous levels of lead.
Speaking this morning, Irish Water’s Head of Asset Strategy Jerry Grant said the company will deal with excessive lead in the public mains.
But the issue is far more prevalent in homes and Irish Water has today begun writing to those householders affected.
There is particular concern about the impact the lead levels will have on pregnant women and small children – prompting the Government to prepare a major awareness campaign. This will be rolled out in the coming weeks.
The issue is on the agenda for today’s Cabinet meeting, with Environment Minister Alan Kelly expected to brief colleagues on the discovery.
Among the measures set to be discussed by ministers today is the rolling out of a grant system targeted at low-income households to help them meet the cost of replacing the pipes.
However, not all households affected will be entitled to state support, a government source told the Herald.
It’s understood that those with higher incomes will be expected to fund the replacement of pipes themselves.
The response from the Government will involve input and financial support from a number of departments, including Education, Environment and Health, for households with lower incomes.
“The main aim, though, is raising awareness about how people can minimise exposure to this public health risk,” said a source. The plan is expected to be closely examined by the Environment Protection Agency (EPA).
Last month, Labour TD Sean Kenny called for a grant scheme to aid in the removal of harmful lead pipes from Dublin homes.
“Dublin city alone was known to have several thousand homes” that still contain internal lead pipes, he said.
Tests on drinking water in homes in Dublin up to last December showed worrying lead levels – with one house in Raheny found to have more than 80 times the maximum safe limit. Public health specialist Dr Anthony Breslin has previously warned of the impact that the metal can have on an individual’s well-being. He said that the full impact of lead exposure was a serious issue that could cause neurological disease.
Irish Water said last month that a national policy to tackle the problem of lead contamination of drinking water would be published in the coming months.