The current quality of Cork city's drinking water is a "potentially serious public health concern", according to a legal submission made by prominent public health specialist, Professor Gabriel Scally.
Issues with water discolouration from Cork city’s main water supply point, the Lee Road treatment plant, have been ongoing since it was upgraded in the summer of 2022.
Residents have been advised by Uisce Éireann to run their taps until the water is clear before drinking it or using the water for cooking, due to concerns about the level of manganese and iron in the supply.
Uisce Éireann accepts there are problems in "pockets of Cork", where it says it has in place a protocol with the HSE to write to customers individually and notify them when there is manganese exceedance.
Professor Scally’s affidavit was lodged as part of a legal case being taken by Friends of the Irish Environment, (FOIE) which was granted permission to go forward last Monday.
FOIE is taking a judicial review against the Environmental Protection Agency for approving Uisce Éireann’s latest 'action plan’, issued in June, to address the drinking water supply problems.
The action plan aims to make the water supply compliant with drinking water regulations in the short-term, mainly by employing a systematic ‘flushing’ method of running water through supply pipes in localised areas to remove discolouration, caused by manganese and iron.
The plan also says that 300km of cast iron pipes will need to be replaced across the city over decades. Only 7.5km have been replaced so far.
However, Professor Scally states that recent water test samples taken by Uisce Éireann show "urgent action is required on public health grounds," due to reoccurring high levels of manganese in the drinking water.
"There is strong evidence that manganese intake, particularly in infancy and childhood, is linked to serious neurological detriment," he states.
Professor Scally cites the World Health Organization’s 2022 ‘International Standards for Drinking Water’ which warns that "several epidemiological studies have suggested that soluble manganese in drinking-water is associated with adverse effects on learning in children".
When contacted by Prime Time, Professor Scally further explained that "the major problem is that manganese, which is a very common metal, can be very toxic".
"There is an increasing amount of evidence that it is particularly toxic for children and young people and can produce neurological problems."
He said he has a real concern for bottle-fed babies "the formula milk may be made up with water that has far too much manganese in it. If that is an ongoing situation, they can really receive an extremely unhealthy dose of manganese".
Professor Scally is also dissatisfied with Uisce Éireann’s advice to Cork residents, which is not to drink discoloured water and "to run the cold water tap in the kitchen for several minutes, as this will usually restore water to a clear colour".
This, he says, "is not in keeping with the international position on manganese pollution of water supplies".
"It's very clear that some forms of manganese can be present in clear water at an excessive dose, and that the only safe way is to test the water for the level of manganese".
Currently a Visiting Professor of Public Health at the University of Bristol, Professor Scally is best known here for carrying out an independent inquiry into the Cervical Check Screening Programme in 2018.
Cork’s water supply problem has been raised repeatedly at local council level and in the Dáil by Cork TDs, most notably by Sinn Féin’s Thomas Gould, as his constituents on the northside of the city are some of the most affected.
Earlier this month, on 6 November, Uisce Éireann’s CEO Niall Gleeson and its Head of Water Operations Margaret Attridge, were asked to appear before the Public Accounts Committee to answer questions on the issue.
Ms Attridge stated that a manganese filter installed at the Lee Road has meant that levels of compliance of drinking water was 94% since January 2025. However, ongoing data sent by Uisce Éireann to the EPA shows high levels of manganese appearing in the water supply intermittently.
For example, on 4 June this year, manganese was found to be way above the regulatory limit of 50 µg/l (micrograms per litres) in three households: at 90 µg/l, 207 µg/l and 254 µg/l. On 7 July, it was at 54 µg/l and 104 µg/l in two different households.
Speaking to Prime Time, Professor Scally also took issue with the public health advice being issued by the HSE.
He said that its current advice, 'FAQs: Manganese in Drinking Water', published in July 2024, is confusing and "very unhelpful".
This document states, in relation to manganese in drinking water, "While the regulatory level is 50 µg/l, (micrograms per litre) there is currently no scientific evidence suggesting any adverse health effects at levels of up to 80 µg/l. You should not drink water with manganese levels above 80 µg/l on an ongoing basis."
The effect of manganese being above this limit elsewhere is described as affecting "the colour (appearing black-ish) and the taste of the water" and can also "stain laundry and plumbing fixtures".
But Professor Scally says "the HSE advice would indicate that people should be quite sanguine about drinking water with levels of manganese above the regulatory level," which in his view, is concerning.
"The regulations are quite clear at European level and in Irish law that it should be 50 micrograms per litre. The HSE guidance talks about it under certain circumstances, potentially up to 80 micrograms: 60% higher. That is clearly out of keeping with the regulations."
Last Monday, Judge Emily Farrell granted permission for the judicial review case to be heard on 1 December next.
In response to Prime Time, the HSE said that it will be putting forward its position in relation to the proceedings in due course, but is not a named respondent.
Uisce Éireann said "public health has always been, and remains, a top priority" for the company, adding that "Cork city's water is safe to drink".
"In 2025, the vast majority of water quality samples taken across the Cork city network have been compliant. There is no area anywhere across the city that experiences elevated manganese levels on an ongoing basis," the company said in a statement.
"We are fully committed to improving water quality in Cork city, with notable progress achieved as a result of actions carried out by our dedicated Cork city water quality taskforce.
"Should an exceedance be confirmed at the plant or on the network, it is reported to the EPA and HSE who provide regulatory oversight and health-based advice, respectively," Uisce Éireann said.
"Our sampling programme confirms a correlation between colour and manganese. Uisce Éireann continues to advise not to drink discoloured water. In the event of discolouration, running the cold kitchen tap for several minutes - we recommend up to 20 minutes - will usually restore water to a clear colour."
The EPA said it is engaging with the Judicial Review process and said it cannot make any comment.
"Uisce Éireann is required to consult with the HSE in the event of elevated manganese levels in drinking water, and this protocol is actively followed. Any queries in relation to public health advice should be forwarded to the HSE," it said.
