The boil water notice has been lifted in parts of Dublin, Kildare and Meath with immediate effect.
However, Irish Water says that the Leixlip treatment plant remains vulnerable.
Over 600 thousand people were affected by the notice which was in place for 8 days after a fault at the plant was caused by heavy rain.
Irish Water says it's working with Fingal County Council to minimise the risk of another Boil Water Notice.
