The Environmental Protection Agency has said Ireland is not investing quickly enough to provide the infrastructure needed to treat waste water.
In its latest report, 'Urban Waste Water Treatment in 2017', the EPA said deficiencies exist in many treatment plants and public sewers.
The report found that raw sewage from the equivalent of 88,000 people in 38 towns and villages flows into the environment every day.
Among its other findings, 28 of Ireland's 179 large towns and cities failed to meet adequate standards to prevent pollution and protect public health.
There were some improvements however, including a fall in the number of priority areas, where treatment needs to improve, from 148 to 132.
Discharges of raw sewage from six urban urban areas has also ceased.
Overall the report is warning that waste water poses a threat to the quality of Ireland's rivers, lakes and coastal waters and is putting our health at risk and called on Irish Water to increase investment.
Commenting on the report Dr Tom Ryan, Director of the EPA's Office of Environmental Enforcement, said: "Ireland is not addressing the deficiencies in its waste water treatment infrastructure at a fast-enough pace.
"It is unacceptable that, 13 years after the final deadline to comply with treatment standards, there are still 28 large towns and cities discharging inadequately treated sewage that fails to meet these standards. This is putting our health at risk and is having an impact on our rivers, lakes and coastal waters."