Approximately 100 houses are without water in the Swinford area.
The water supply was impacted as a result of a burst main on the R320 outside Tesco in the town.
The areas affected are Frauin Hill, Beech Park, Kiltimagh Road, Ash Grove, Oak Drive and Larch Hill.
Irish Water and Mayo City Council say repairs are ongoing and it is expected that the burst will be fixed by 4pm.
Some customers may not receive a full water supply for a further two to three hours while water returns to the network.
Irish Water understands the inconvenience when a burst occurs and thanks customers for their patience while we work to repair the burst and restore normal supply to impacted customers.