Raw sewage from the equivalent of 54,000 people in 26 towns and villages is still discharged into the environment every day in Ireland.
Wastewater treatment at 15 large urban areas, including Dublin, did not meet EU environmental standards, while 26 towns and villages discharge raw sewage every day as they are not connected to treatment plants.
It will take a multibillion-euro investment to bring all wastewater treatment systems up to standard and at least two decades to complete, the EPA warned.
Less than half of wastewater in Ireland is treated to European standards despite Brussels requiring Ireland to do so 30 years ago.
While acknowledging it has made considerable progress in some areas, the EPA urged Uisce Éireann to use its new investment plan to finally tackle wastewater in 89 areas of specific concern across the country.
EPA director Tom Ryan said: “While it is encouraging to see continued progress in stopping the unacceptable practice of discharging raw sewage into our environment, wastewater remains a significant pressure on Ireland’s waterways and is adversely impacting water quality.
The pace at which Uisce Éireann is delivering improvements needs to accelerate.”
The EPA said poor practices at plants including two in Cork prolonged the issue.
EPA programme manager Noel Byrne said: “It is welcome that Uisce Éireann is currently building infrastructure at large urban areas, including Ringsend and Arklow.
However, poor management practices at upgraded plants, such as Skibbereen and Courtmacsherry, caused inadequately treated sewage to discharge into the environment.
"This is not acceptable as these plants have sufficient treatment capacity.”
Uisce Éireann said over €450m was invested on wastewater treatment in 2022, the highest annual spend to date, as it targets priority areas for raw sewage entering rivers, lakes, the sea, and sites identified by the European Court of Justice under the Urban Waste Water Treatment Directive.
