More than 800,000 people are receiving water from supplies identified as being at-risk.
The Environmental Protection Agency published a list of 119 supplies that require remedial action. It said that the number of people affected had risen by 21,000 in the past four months.
Irish Water yesterday vowed to address 29 of the sources on the EPA’s list by the end of the year.
Problems with the affected supplies include lack of effective disinfection and inadequate control of trihalomethanes (THMs) — cancer-linked toxins.
Another common problem is ineffective barriers to cryptosporidium – a source of gastroenteritis caused by land runoff getting into drinking supplies.
Irish Water said it would be spending €2 billion on improving the country’s drinking water supplies between now and 2021, including