Works to remove threat to Limerick City's water supply 'behind schedule'

Treatment plant, which provides drinking water to a population of almost 115,000, placed on EPA’s Remedial Action List in September 

The latest audit, which was carried out at the end of February, showed THMs levels monitored so far this year were below the recommended safety limit.

Uisce Éireann has told the State environmental watchdog that it will not meet the target of the end of 2023 for completing upgrade works to remove the threat posed by persistent high levels of chemical compounds in Limerick city’s water supply.

A recent audit of the Limerick City Environs Public Water Supply by the Environmental Protection Agency (EPA) revealed that the utility company (previously known as Irish Water) had not provided a timeframe for the completion of works to address exceedances of recommended limits for trihalomethanes (THMs) in the supply.

The treatment plant, which provides drinking water to a population of almost 115,000, was placed on the EPA’s Remedial Action List in September as a public water supply deemed “at risk” and in need of corrective action.

The plant at Clareville was placed on the list due to persistent excessive levels of THMs above the recommended limit of 100 µg/l last year.

However, the latest audit, which was carried out at the end of February, showed THMs levels monitored so far this year were below the recommended safety limit.

THMs are by-products of the disinfection process for drinking water and are chemical compounds which form as a result of reaction between organic materials such as soil and rotting vegetation and chlorine which has been added as a disinfectant.

Links to cancer

Long-term exposure to high THM levels has been linked to diseases of the liver, kidney and central nervous system as well as bladder and colon cancer.

The audit showed Uisce Éireann had admitted that the upgrade works to enable the removal of the supply from the Remedial Action List were progressing more slowly than planned.

The works include a new chlorine dioxide unit, reservoir cleaning and further testing to fully understand why THMs are building up in the supply.

The plant, which is operated by Veolia on behalf of Uisce Éireann, produces around 43,000m³ per day, approximately half its current capacity.

However, Uisce Éireann is progressing works to increase its capacity to around 100,000m³ daily which allow the Clareville plant to replace and augment a number of satellite supply zones in the area.

The audit also highlighted how some recommendations from a previous inspection of the plant by the EPA in September 2020 have still not been implemented.

They include the need to ensure a minimum pH level in the supply in order to minimise the levels of lead in drinking water.

What's your view on this issue?

You can tell us here

Uisce Éireann said the work to address the issue was ongoing.

It confirmed that weekly monitoring for cryptosporidium because of deficits in the treatment process to remove organic material had to date found no traces of the potentially dangerous microscopic parasite that can cause gastroenteritis.

The audit revealed that there are no alarms at chlorine “booster” stations located at reservoirs in Newcastle and Friarstown to alert staff to issues with chlorine levels.

Uisce Éireann also admitted that it had not inspected and cleaned the Newcastle reservoir as recommended in September 2020 as “a matter of priority.”

The Limerick city plant was the largest of 59 public water supplies affecting over 481,000 people on the EPA’s remedial action list at the end of 2022.

Other large supplies on the list include Kilkenny, Wexford, Longford, Listowel Co Kerry; Trim, Co Meath; Fermoy, Co Cork and Nenagh Co Tipperary.