A swimming ban has been put in place at several locations in Dublin following an overflow from the wastewater treatment plant in Ringsend.
Dollymount Strand on the northside of Dublin Bay is affected by the ban, as well as Seapoint, Sandycove and the Forty Foot on the southside.
Separate bathing prohibitions are already in place at Sandymount and Merrion beaches due to general issues with water quality.
Irish Water has said that heavy rainfall in the Dublin area at the weekend caused the overflow.
Dublin City Council has said that the prohibition will remain in place pending testing of the water at Dollymount.
Notices warning bathers not to enter the water will be put up at the beach.
Dún Laoghaire-Rathdown Council, which issued the notices for the southside beaches, has said the ban is in place pending the results from tests of water quality.
The results of these tests are due in three days.
The council has said the ban does not affect other beaches in the area or Dún Laoghaire Harbour.
The ban comes into place as Met Éireann forecasts higher temperatures for much of the country this week.
The forecaster has said temperatures may reach 27 degrees Celsius on Thursday, before lower temperatures return at the weekend.