Tankers of water are being made available to households in an area of Swords in north Dublin following a warning that the supply has been contaminated by Escherichia coli.
Fingal County Council issued a public alert about the water to 160 homes in the Knocksedan Estate last week.
Residents in the area have been advised not to use tap water for brushing teeth, preparing food or bathing children.
Fingal County Council is still working to identify the source of the contamination. But Green Party Councillor Joe Corr said that a water mains pipe was breached last week and the supply was contaminated, probably by agriculture run-off.
That breach has been isolated and repaired, according to Cllr Corr, and the Council is now conducting tests to ensure that the water supply gets back to normal in the next few days.