Uisce Éireann making great strides in addressing all Trihalomethane (THM) risks in public water supplies
25 January 2024
Uisce Éireann notes the recent judgement by the Court of Justice of the European Union in relation to trihalomethane (THM) exceedances. Public health is our top priority, and we continue to invest in our infrastructure and implement operational improvement measures to adhere to the standards set out in the Drinking Water Directive and deliver world class drinking water supplies for all our customers.
This includes intensifying monitoring practices, implementing cutting-edge water treatment technologies, and collaborating closely with relevant stakeholders.
Uisce Éireann has prioritised investment in the schemes identified in the Court of Justice of the European Union infringement case as at risk from THM exceedances. Of the original 74 public water supplies included in the first European Court of Justice infringement letter, all but five of these have now been addressed. For those that remain, Uisce Éireann has comprehensive plans in place to address the issues either through upgrades or rationalisation of existing treatment plants. Uisce Éireann’s enhanced testing and monitoring programme has also enabled the utility to identify a number of additional sites where THM risks exist. In all these cases Uisce Éireann is taking action to remove the risk of elevated levels of THMs forming in all public water supplies through a combination of plant upgrades and enhanced operational controls.
Uisce Éireann is determined to address the remaining THM non-compliances effectively, and we have already made significant progress in addressing these issues. We will continue to prioritise the remaining schemes identified by the ECJ as quickly as possible.
It is important to assure customers on the remaining schemes that water is safe to drink, THMs are chemicals which are formed by the reaction of naturally occurring dissolved organic material in the water and chlorine, which is used for disinfection purposes. Chlorination is an essential step in the production process to ensure harmful bacteria are eliminated from your drinking water. The clear advice from the HSE in relation to THMs and drinking water is that the "benefits of using chlorine to treat our drinking water are much greater than any possible health risk from THMs". This is also the position of the World Health Organisation (WHO) which states that “...adequate disinfection should never be compromised to control THMs".
When our monitoring programmes detect THM levels above the allowable limit (100µg/L), Uisce Éireann notifies the Environmental Protection Agency and consults with the Health Service Executive (HSE) to ensure any potential risk to public health is fully risk assessed. To date, a Do Not Drink notice has not been imposed on any public water supply due to THM exceedances.