Almost 300,000 people across 15 counties to be notified of high levels of cancer-linked toxins in their drinking water

Uisce Éireann is to send explanatory booklets to affected households served by 25 water supplies in 15 counties.

It will inform customers that their water supply has elevated levels of trihalomethanes (THMs) which some studies suggest are linked to various cancers and reproductive problems.

THMs are chemical compounds created when chlorine used to disinfect supplies at treatment plants reacts with vegetation and bacteria in the water.

The HSE acknowledges the concerns about the links to disease but says the risks of drinking inadequately disinfected water are higher.

The European Commission takes a tougher stance, however, and Ireland was found guilty by the European Court of Justice in January of providing unsafe drinking water to hundreds of thousands of people whose supplies had THM levels above legal limits.

“THMs are of concern for human health and the environment since long-term exposure to high levels of these chemical compounds in drinking water may pose risks such as cancer, in particular bladder cancer and colon cancer, and cause gastrointestinal problems and skin irritation,” the court said in its judgment.

“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,” it added.

The judgment followed almost a decade of correspondence from the commission, urging the Irish authorities to resolve the problem.

Friends of the Irish Environment (FIE), the group which made the initial complaint to Europe, welcomed the court’s findings but argued there was also an urgent need to tell the public directly which water supplies were tainted.

The information is in Environmental Protection Agency (EPA) documents but is not user-friendly for the public

Uisce Éireann last notified householders in affected areas in 2018 but since then, some of those water supplies have been upgraded while others have become a focus of concern.

FIE sent the EPA a solicitor’s letter last week threatening legal action if the agency did not direct Uisce Éireann to immediately inform affected customers.

In response, the EPA said there were currently 25 public water supplies serving 297,447 people on its remedial action list (RAL) because of high levels of THMs.

“The remediation of all these drinking water supplies remains a serious concern for the agency,” said Dr Tom Ryan, EPA enforcement director.

“In light of the judgment, the agency met with Uisce Éireann and the HSE to consider further its implications, the public health risks and potential actions that should be taken,” he said.

“In particular, the importance of keeping the public informed on water quality issues. ​

“Uisce Éireann has committed, as part of their statutory obligation, to keep consumers informed with respect to THMs and other water quality issues, to updating the booklet that was issued in 2018 and distribute it to current consumers on the agency’s RAL.”

Dr Ryan said the EPA was also consulting with the HSE on the short- and long-term health implications of elevated THM levels.

He said the HSE’s current advice dated to 2011 but that was being reviewed.

FIE spokesman, Tony Lowes, said it was too soon to lift the threat of legal action against the EPA.

“The group will consider the EPA’s letter, but we are extremely disappointed with the level of detail and commitments it contains,” he said.​