More than half a million people are drinking tap water which contains higher than permitted levels of potentially cancer-causing chemicals.
The Environmental Protection Agency (EPA) reassured consumers yesterday after an environmental organisation revealed that almost 600,000 consumers are drinking water which exceeds World Health Organisation limits for the chemicals.
Friends of the Irish Environment called on the EPA to notify people whose public water supplies contain higher than permitted levels of trihalomethanes (THMs).
EPA data, received by the group under EU regulations which grant public access to environmental information, showed that 598,951 consumers were receiving water with excessive levels of trihalomethanes.
THMs are a by-product of the chlorination of water containing brown organic matter such as peat.
Prolonged consumption of drinking water with high levels of THM has been linked to diseases of the liver, kidneys, bladder and central nervous system, as well as with an increased risk of cancer.
In a statement yesterday, the EPA said chlorination of water supplies ensures that safe drinking water can be provided to consumers, and the process almost completely eliminates the risk from deadly waterborne diseases.
However, it acknowledged that the chlorination process also produces by-products, including a group of chemicals known as trihalomethanes.
“The health risks from disinfection by-products, including THMs, are much less than the risk from consuming water that has not been disinfected,” the authority said.
Local authorities were encouraged to make every effort to ensure that concentrations of such by-products are kept as low as possible without compromising the effectiveness of water disinfection.
The EPA said it was currently carrying out research to assess the extent of excessive THMs in public water supplies.
“The EPA recommends that if anyone is concerned about their tap water they should contact their local authority who have the most up-to-date results and who will make them available upon request.”
Alternatively, results of drinking water monitoring may be available directly from local authority websites.
The Irish EPA figures for 2009 show that 16pc of public water supplies now fail the safety limits set by the WHO for THMs.
The EPA has already revealed that compliance with chemical standards in council drinking water supplies fell in 2009 because of THM breaches.
Friends of the Irish Environment said : “The public must be made aware of the fact that their water supplies exceed the permitted chemical contamination . . . because consumers have the right to know what dangers they are exposed to.
– Treacy Hogan Environment Correspondent