The Environmental Protection Agency has said that over 100 drinking water supplies are in need of remedial action to avoid the risk of water restrictions.
While its latest report on the quality of drinking water in the public supply has found that over 99% of supplies complied with both the microbiological and chemical standards, the EPA has warned that 108 supplies are at risk.
These supplies serve 830,000 consumers.
EPA Director of Environmental Enforcement Gerard O’Leary said: "So far this year, 86,000 people have had to boil their water to make it safe.
"This is more than twice as many as last year. Without investment to address the deficiencies in the supplies on the EPA’s Remedial Action List, this type of water restriction will continue to occur."
There are currently 17 supplies operating with boil-water notices.
The largest is Ballinlough/Loughlynn in Co Toscommon which serves 3,500 people.
Its supply is affected by cryptosporidium.
Speaking on RTÉ's Morning Ireland, EPA Senior Inspector Darragh Page EPA said the agency had taken two cases against Irish Water in relation to water supplies in Letterkenny, Co Donegal and An Cheathrú Rua in Galway.
Mr Page said the Vartry-Roundwood scheme in north Wicklow/Co Dublin needs a new pipeline to be constructed as it is at risk of collapse.
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