The European Commission said it made the referral because the level of the chemical substance trihalomethanes (THMs) in drinking water exceeds EU limits in a number of water supply zones across the whole country.

Drinking water provided in 30 water supply zones in Ireland, serving a population of more than 200,000 citizens, continues to exceed the safe levels of THMs, the Commission said.

THMs are formed in drinking water due to the disinfection process. Exceeding the parametric value of THMs can entail potential risks to human health.

The European Commission sent a letter of formal notice to Ireland in 2018, followed by a reasoned opinion in May 2020. The reasoned opinion concerned 44 water supply zones across the whole country, of which 30 allegedly remain in breach of the THM value.

“Whilst the Commission welcomes the fact that Ireland has made progress in addressing elevated levels of THMs in the drinking water, today, more than three years after the opening of the infringement case, a number of water supply zones still do not comply with the requirements of the Drinking Water Directive,” the Commission said.