A temporary ban has been placed on three Dublin beaches. Dublin City Council has warned bathers not to swim at Sandymount Strand due to the water quality.
While Dun Laoghaire/Rathdown County Council has banned swimming at Killiney and White Rock beaches due to high levels of E Coli.
Water samples taken at Sandymount Strand and Half Moon Swimming Club in South Wall on Monday showed that the water quality at these locations did not comply with the minimum standards for bathing waters.
"A further sample has been taken today the result of which will be available on Friday" the Council says.
If the water quality is in accordance with the required standards the prohibition notice will be lifted, it adds.
Dublin City Council says it has yet to determine what has caused the drop in water quality, but is carrying out further investigations.
Bathing water quality can be impacted by factors such as weather and tidal conditions, faecal matter from dogs and birds as well as temporary overflows from drains.
The Council says it has consulted with the Health Service Executive (HSE) and the Environmental Protection Agency (EPA) on the matter. It comes as temperatures are set to reach 22 degrees today.
