Almost 100 drinking-water samples had outside the allowable limit of lead, or an environmental pollutant.
That's according to Irish Water's most recent test results, released under the Freedom of Information Act.
Irish Water recently sampled drinking-water at 674 properties to test them for lead.
There were seven failures, with homes in Cavan, Cork, Donegal, Limerick, Roscommon and Kerry all outside the allowable limit.
Dr Michelle Minihan, a senior inspector with the Environmental Protection Agency, says long-term exposure to it can cause serious harm.
There are no lead water mains in Ireland any more, but they were used here until the 1970s - so some homes still have lead pipes.
But Dr Minihan wants Irish Water to speed up the replacement of these.
Irish Water also recently sampled nearly 1,200 supplies to see they had under the allowed limit of THMs.
These are environmental pollutants caused by adding chlorine to water, and some studies suggest they are linked to cancer.
There were 91 failures across 17 countries - with one sample in west Clare over twice the limit.
