Uisce Éireann has said it is important to reassure customers that the water from supplies on the remedial action list for Trihalomethane chemicals is safe to drink.
Trihalomethanes or, THMs, are chemicals formed by the reaction of naturally occurring dissolved organic material in the water and chlorine, which is used for disinfection purposes.
The water utility said 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”.
It said that the World Health Organisation agrees that adequate disinfection should never be compromised to control THMs.
The need for reassurance from Uisce Éireann has arisen following the judgement of the European Court, two weeks ago, that Ireland had failed to meet its obligations under an EU directive on safe drinking water at 74 water supplies where THM levels had exceeded the EU safe limits.
Uisce Éireann said the vast majority of the 74 public water schemes referred to the European Court have now been addressed, with just five of the original schemes remaining.
It said projects are also underway at all the remaining five locations to address the issues either through upgrades or rationalisation of existing treatment plants.
In a statement Uisce Éireann said: “There are currently 25 schemes on the EPA’s Remedial Action list for THMs.
“In all these cases we are taking concerted action to remove these risks through a combination of plant upgrades and enhanced operational controls”.
Uisce Éireann notifies the Environmental Protection Agency and consults with the Health Service Executive (HSE) if THM levels in drinking water exceed the allowable limit of 100 micrograms per litre.
This is to ensure any potential risk to public health is fully risk assessed.
To date, no “do-not-drink” notices have been imposed on any public water supply due to THM exceedances following such consultations with the health and environment authorities.
Long-term exposure considered dangerous
Nevertheless, long-term exposure to trihalomethane chemicals is considered dangerous to both human health and to the environment.
Friends of the Irish Environment Director Tony Lowes had originally initiated the complaint about THM’s in Irish drinking water.
His complaint was eventually taken up by the European Commission who took the case to the European Court.
The Court heard long-term exposure to high levels of THM chemicals in drinking water may pose risks such as cancer risks, in particular bladder cancer and colon cancer, and cause gastrointestinal problems and skin irritation.
Moreover, THMs, once released into the environment, may be toxic for aquatic wildlife, disrupt freshwater ecosystems and contribute to the formation of ‘dead zones’ in the oceans by encouraging excessive growth of algae.
In its judgement two weeks ago the European Court said Ireland’s failure to comply with the parametric value set for THMs constitutes, by definition, a potential danger to human health, since water that does not meet that minimum requirement and cannot be considered to be wholesome and clean.
Mr Lowes said now that the European Court has established that THM exceedances are a danger to public health, the Irish authorities are under a legal obligation to notify every household receiving water above the THM limits that the product represents a danger to their health.
He noted that the number of consumers receiving supplies that exceed THM limits more than doubled to over 235,000 people over the last two years.
The latest list includes sizable supplies such as Limerick City and the Barrow supply in County Kildare.
Uisce Eireann said that is now taking advice on whether it needs to warn consumers in circumstances when their drinking water contains levels of Trihalomethanes in excess of the EU limits.
