Works on a burst water main in east Cavan should be completed by 8pm tomorrow evening.
It had been hoped that water would be fully restored by 8pm this evening, but Irish Water says it is proving difficult to locate a major leak.
The issue is causing supply disruptions to Lisnahederna, Crossbane, Killiter, Mullagh and the surrounding areas.
A water tanker will be available at Crossreagh National School and Mullagh Heritiage Centre.
Irish Water says every effort is being made to ensure that the alternative drinking water supply is adequately disinfected.
However, it is advised that any water obtained from a tanker should be boiled before use as a precautionary measure.