Irish Water need to put a plan in place urgently to stop wastewater leaks into Dublin Bay, according to a Dún Laoghaire-Rathdown county councillor.
A swimming ban for beaches and swimming areas on the southside has been extended until Monday by the council.
They have been shut down because of an overflow of partially-treated sewage at a Ringsend wastewater treatment plant on Thursday night.
Fine Gael Councillor Barry Ward says Irish Water needs to get a handle on the situation.
"It's very disappointing that the ban now has been extended to Monday," said Cllr Ward.
"It's really not acceptable. We are not strangers to heavy rainfall in Ireland yet it seems like Irish Water has made no preparations to allow for that and to ensure that there isn't another sewage outflow in Dublin Bay.
"Once again bathing water has been compromised, once again people living in Dublin, Blackrock, Sandycove etc can't go swimming in a natural amenity that is on their doorstep."
Green Party MEP Ciarán Cuffe has called on Irish Water to speed up the works at the Ringsend plant to prevent more beach closures.
"I think it's unfortunate that this has happened and I think it underlines the need to upgrade the sewage treatment system in Dublin," said Mr Cuffe.
"A lot of those works are already underway but I hope that they can be speeded up so that incidents like this are less likely to occur."
Meanwhile in County Clare, a 'Do Not Swim' notice has been issued for Kilkee beach after a discharge of wastewater into the sea via Kilkee beach.
Clare County Council said that members of the public are advised not to swim or engage in other recreational activities in the water on the advice of the HSE.
It said that Irish Water is aware of the wastewater incident.
The Council has raised red flags at Kilkee beach and removed the Blue Flag until water quality tests allow for the 'Do Not Swim' notice to be lifted.
