High winds which blew debris onto the inlet screens at Meencrumlin water treatment plant led to a loss of water supply and or water pressure issues over the weekend for customers in the Finn Valley area.
Irish Water says customers in higher lying areas were most affected by what they described as this unusual and unplanned event.
The towns affected were Ballybofey, Stranorlar, Killygordon, Cloghan, Liscooley, Donneyloop, Crossroads, Castlefinn, Drumkeen, Convoy, Raphoe, Ballindrait and Lifford.
Irish Water says high winds blew debris onto screens, impeding the flow of raw water into the Water Treatment Plant. They say the situation was made worse by the current low lake level as a result of record low rainfall levels recorded over March, April and May.
Irish Water says it is working with Donegal County Council, contractors, and others to safeguard the health and well-being of both staff and the public and to ensure the continuity of critical drinking water and wastewater services.