The court found that the concentration of the the chemical compound trihalomethanes (THMs) in drinking water in a large number of public water supplies was above safety limits, since at least 2012.

The compliance deadline was 2003.

The CJEU found that Ireland could not justify its failure. THMs are used to remove bacteria and are formed as organic matter and chlorine interact. They are deemed to be dangerous to humans and the environment with high levels causing cancer.

The findings pertain to 21 public water supplies and nine private schemes. The ruling handed down yesterday requires Ireland to comply without delay and pay legal costs in the case.

The European Commission could also bring an additional case seeking financial penalties for ongoing delays in Ireland’s compliance with the EU directive on drinking water standards.