Five bathing areas out of 131 have failed to reach mandatory European Union water quality standards according to a new report from the Environmental Protection Agency (EPA).
The non-compliant bathing areas include beaches at Merrion Strand (Dublin city), Sutton Burrow Beach (Fingal County Council) Na Forbacha and Clifden (Co Galway) and Ardmore (Co Waterford).
The EPA said 96 per cent of the bathing water sites tested were compliant with EU Mandatory Standards.
Gerard O' Leary, programme manager, EPA said: "The bathing water quality in some areas has declined in recent years and now does not meet the minimum standards. This trend needs to be addressed".
"However, significant improvement in water quality at some popular beaches near urban areas is evident in recent years due to the provision of wastewater treatment facilities in key locations," said Mr O' Leary.
The EPA report also said that water areas in Galway (Silver Strand and Salthill) had under gone an improvement in bathing water quality since 2003.
The report said that a major contributory factor to this improvement was the commissioning of a new wastewater treatment facility at Mutton Island close to Salthill in May 2004.