Untreated sewage is still being pumped into our water at 44 locations.
A new Environmental Protection Agency report found waste water treatment in over a quarter of Ireland's large towns and cities is below public health standards.
The report says 50 major towns and cities including Dublin, are failing to meet waste water treatment standards.
Meanwhile, counties Cork and Donegal account for nearly half of the 44 areas where there is no treatment at all.
In 59 locations, waste water is the sole pollution threat to waterways, with almost one quarter of these in Donegal and Galway.
The report says there are four areas, where waste water makes swimming a health risk, including Merrion Strand and Loughshinny Beach in Dublin.
The EPA says major investment is needed in our water treatment facilities if Irish seas, rivers and lakes are to meet environmental standards.