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 half a million 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.
