Despite clear progress being made in wastewater treatment, there is still much room for improvement according to the Environmental Protection Agency's (EPA) Urban Wastewater Treatment in 2023 report.

A 45 percent reduction in the number of towns and villages discharging raw sewage since the beginning of last year were recorded, however, wastewater treatment at many areas is not good enough to prevent wastewater discharges from impacting the quality of rivers, estuaries, lakes and coastal waters.

Uisce Éireann estimates that it could take over two decades and will require substantial investment to bring all deficient wastewater works up to the standards required to protect the environment, although the EPA believe this timeframe is too long.

As it is not possible to fix all of the problems immediately, the EPA has identified 73 priority areas where improvements in wastewater treatment are most urgently needed to protect the environment. Uisce Éireann has not yet started upgrade works at half of these.

"Investment has resulted in stopping raw sewage discharges during the past year from 13 towns and villages that were priority areas highlighted by the EPA," said Dr Tom Ryan, EPA Director.

"This demonstrates that such investment protects our environment and benefits our local communities. The much-needed upgrade of Ireland’s largest treatment plant at Ringsend in Dublin, treating over 40 per cent of all national wastewaters, is now well advanced, and this is to be welcomed.

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"However, wastewater discharges continue to be a significant pressure on water quality in many of our rivers, estuaries, lakes and coastal waters. Without an ambitious and sustained investment programme to build out our wastewater treatment infrastructure it could take over two decades to achieve the required standards to protect the environment," he continued.

"At an operational level, Uisce Éireann's slow progress in designing and delivering the solutions needed at the waters most affected by wastewater discharges are prolonging impacts on water quality. Uisce Éireann must prioritise the prompt delivery of these essential works."

The Urban Waste Water Treatment Directive sets general European wide treatment standards for large towns and cities. Ten areas, including Dublin, failed these basic standards in 2023.

Wastewater discharge licences issued by the EPA to Uisce Éireann may specify more stringent standards than those in the Directive when such standards are necessary to prevent and reduce pollution of waters. Over half of licensed treatment plants discharge wastewater that does not always meet these licence standards.

Noel Byrne, EPA Programme Manager, said: "Wastewater discharge licences issued by the EPA set out the treatment standards needed to prevent pollution by wastewater discharges and protect our rivers and coastal waters. It is unacceptable that over half of licensed treatment plants do not always meet these standards, with issues ranging from short term breaches of treatment standards up to continuous discharges of raw sewage.

"The short term breaches should be resolved through effective management and maintenance of equipment. Uisce Éireann must address infrastructural deficits at the priority areas highlighted by the EPA during its 2025 to 2029 investment cycle. This will help deliver significant environmental benefits and protect water quality."

The report, which is now available on the EPA website, includes a range of recommendations for Uisce Éireann, including the need to speed up its overdue assessments of how wastewater discharges impact shellfish waters, and to collect better information about discharges of untreated wastewater through storm water overflows.