Irish Water will need 25 years to reduce leakage to acceptable levels – and at least 10 years to eliminate lead piping from public mains.
A report released by the company lists Shannon as a town that fails to meet EU Standards.
While the state utility also includes Ballyvaughan, Clarecastle, Kilkee, Kilrush and Liscannor as locations where raw sewage flows into the sea.
The details are contained in Irish Water's 25 year investment plan being published today.
Irish Water's investment plan lays the blame for the state of Ireland's water supply on funding from successive Governments which "rarely met the levels required".
Its plan for the next decades ahead – which will be unveiled later – says it will take at least 25 years to reduce leakage to acceptable levels – warning that 38 per cent of our water will still be lost by 2021.
2021 is also the target date to eliminate all boil water notices – while bringing all waste treatment plants to EU standards will also take a quarter of a century.
Meanwhile, the company says Dublin will need a new supply of water by 2020.
And the report also shows Irish Water will need to reduce investment in the network by 300 million euro between now and next year due to a lack of funding.
