Five beaches on the southside of Dublin have had swimming restrictions put in place until Sunday.
The Forty Foot, Seapoint, White Rock, Sandycove and Killiney may have become polluted after heavy rain.
Also, the water quality may also have been affected at Velvet Strand in Portmarnock.
Paul Wynne from the Half Moon Swimming Club said warnings are being issued constantly.
Mr Wynne said: "A lot of people are using the facilities around the bay, probably more now than ever before and with constant water warnings people will become more cautious of getting into the water."
Mr Wynne, who swam at Seapoint yesterday, said he did not know about the restrictions until today.
He said: "I was out there yesterday, I didn't realise there was a warning and certainly there were no notices to that effect. The lifeguards were on duty and they weren't preventing people from swimming.
"It was news to me this morning that there was a notice enforced, it wasn't in the newspapers but it was listed on beaches.ie, and even there, it's not that it's a hard find but you've got to scroll down through all the beaches, they are not listed alphabetically."