Tests by Irish Water have found lead concentrations 15 times the limit deemed safe to consume in drinking water in one area in Co Roscommon, and nearly 10 times the limit in an area of Co Waterford.
Audits in recent years by Irish Water found 33 cases where drinking water had lead concentrations above the safe limit of 10 micrograms (µg) per litre , with each case reported to the Environmental Protection Agency (EPA).
The highest levels of lead in drinking water were found during a test of drinking water from a tap in one part of Co Roscommon, which was 148µg when a sample was tested in 2020.
A test of drinking water in Joanstown, Co Waterford, in June 2021 found lead concentrations of 98µg , nearly ten times the safe limit.
A reading of 56µg per litre of lead in drinking water was taken from tap water tested in a home in South Dublin County Council.
The Health Service Executive advises if the levels of lead are above 10µg per litre, households should consider finding “safe drinking water from some other source”, particularly when it came to bottle-fed infants, young children or pregnant women.
Tests found high levels of lead in drinking water in 12 different counties, including Cork, Wicklow, Wexford, Limerick, Donegal, Cavan and Mayo.
The results of the internal audits of drinking water were released to The Irish Times under the Freedom of Information Act.
There were 49µg of lead per litre found in drinking water at one home that was supplied by Burncourt regional water supply in Co Tipperary.
High levels of lead were also found in a location in Dún Laoghaire Rathdown County Council (41µg), and three times the safe limit in drinking water in both Kishkeam, north west Cork, and in Ross, Kildermody, Co Waterford.
Irish Water said when water left its treatment plants it was “lead free” and that none of the country’s water mains used lead pipes.
In homes built before or during the 1970s it was likely some of the pipework connecting the home to the mains contained lead pipes, it said.
The national water utility said it was aware of an estimated 180,000 service connections, which were short pipes connecting a home to the water mains, that were made of lead.
The agency had replaced 42,000 of these pipes to date, with plans to replace a further 48,000 lead pipe connections by 2030, it said.
A spokesman for Irish Water said it had started using orthophosphate to treat lead pipes, which forms a protective coat inside pipes to stop lead getting into a home’s drinking water.
The Department of Housing also had grants where homeowners could claim up to €5,000 of the cost of replacing lead pipes on their property, the spokesman added.