Water supply is returning to customers in west Roscommon, according to Uisce Éireann.
It follows repairs carried out at Longford Springs Water Treatment Plant.
Supply has returned to customers in Castlerea town area.
However, customers in Ballintober, Trien, Kilmurrary, Castleplunkett and areas on the periphery of the scheme may continue to experience intermittent outages and/or reduced pressure over of the course of the day.
Uisce Éireann have thanked customers for their cooperation.