Water treatment schemes in Sligo and Donegal are among 38 that are failing to meet EU standards and are now part of a court case being taken by the European Commission.
The schemes include Tubbercurry in Sligo and Killybegs in Donegal.
The EU says the necessary steps aren’t being taken to prevent serious risks to human health and the environment.
Under EU law, towns and cities are required to collect and treat waste water.
Tim Hayes of the EU office in Dublin says the Government here has not adequately addressed this issue since 1991: