Dun Laoghaire Rathdown County Council says the water at Sandycove Beach is now clear and safe to swim.
This followed the re-opening of Seapoint and the Forty Foot beaches on Thursday.
The council says water quality results received for Sandycove have shown the water quality has returned to clean and normal.
Following a consultation with the HSE, all temporary bathing prohibition notices have been removed.
The council adds that all designated and non-designated bathing areas along its coastline have been tested and proved clear.
"All are open and safe to swim in," it says.
Rainfall on Sunday and Monday had led to waste water overflow at a number of treatment facilities and pumping stations in the bay area of south Dublin.
While bathing prohibitions are expected to remain in place for the entire 2019 bathing season at Sandymount and Merrion beaches, due to general water quality issues, unrelated to this week's bans.