Uisce Éireann has said it is taking advice on whether it needs to warn some householders in the Glwenties and Ardara area that their drinking water contains a level of toxic chemicals called trihalomethanes in excess of that permitted under European Union limits.
The Donegal householders are among more than 220,000 consumers which may be effected by the chemicals.
The Irish Times reports that the State water authority has been working for several years to eliminate trihalomethanes, known as THMs, from drinking water supplies which were the subject of a European Court of Justice (ECJ) finding against Ireland in recent weeks.
However, the Environmental Protection Agency’s remedial action list now cites water supplies not named in the ECJ case which exceed the European Union’s limit for THMs of 100 microgrammes per litre. THMs can arise when chlorine is added to peaty water as part of the purification process.
Affected supplies include: those serving Limerick city, where 114,764 people are exposed to the toxins: Listowel in Co Kerry, where 14,905 people are exposed; and parts of Kilkenny city, where more than 14,000 people are also exposed.
Smaller areas such as Castletownbere, Co Cork, Glenties-Ardara in Co Donegal and Aughrim, Co Wicklow, are also affected.
Under a legal process to transpose the EU Drinking Water Directive into Irish Law in 2014, it was determined that where Uisce Éireann, in consultation with the Health Service Executive, “considers that a supply of water intended for human consumption constitutes a potential danger to human health” those affected should be “informed promptly” and “given the necessary advice” to safely consume water.
In its recent decision against Ireland, the ECJ said: “In the present case, the failure to comply with the parametric value set for THMs constitutes, by definition, a potential danger to human health.”
The ruling would at least appear to oblige Uisce Éireann to notify nearly a quarter of a million people of the risks associated with their supplies. Asked if it intended to do so, the utility company replied: “We are taking the decision under advisement at this time.”
Uisce Éireann said it had made good some 70 schemes named in the original ECJ case and “it is important to assure customers on the remaining [five] schemes that water is safe to drink”.
Uisce Éireann said it took advice from the HSE concerning THMs and drinking water. It said the advice was 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 World Health Organisation position which states that adequate disinfection should never be compromised to control THMs, added Uisce Éireann.
However, Friends of the Irish Environment, which made the original complaint about THMs in drinking water in 2010, said the issue was not about disinfection.
“Nobody wants to stop disinfecting supplies. What is required by the EU Drinking Water Directive is to eliminate the THMs,” said its director Tony Lowes. “People could do this themselves with a €70 charcoal filter, but Uisce Éireann needs to warn consumers about that … There can no longer be any doubt since the ECJ decision, that consumers should be notified.”
