Irish Water has appealed to people in Co Galway not to run their taps to ensure unnecessary demand is not place on supplies in the region.
The agency has imposed water restrictions on customers served by the public supply in An Cheathrú Rua in Conamara because of what it says is "exceptional demand and mechanical issues" at the local treatment plant.
It is understood a problem with pumps at the plant has left 4,700 households without water.
The restrictions came into effect this evening.
Water will be restored in the morning but further constraints are expected again on Friday afternoon and could continue for a number of days.
Irish Water says the cold weather is causing problems with water treatment and is also impacting on efforts to repair the faults there.
The problem comes just over a year after a boil water notice was lifted for customers in An Cheathrú Rua, after €1 million was spent on the new treatment plant for the area.
Elsewhere, reduced pressure or loss of supply is likely in the coming days for customers in Kilkerrin/Moylough, Williamstown, Tír an Fhia, Letterfrack, Tully, Clifden and Clonbur.