Homeowners are being asked to conserve water amid a surge in demand due to the warm weather.
Irish Water says it's dealing with outages in parts of north Dublin, as well as Donegal and parts of Kerry.
The utility says it's working with local authorities to restore supplies to normal levels.
Tom Cuddy from Irish Water is appealing to people to only use water for what's necessary due to depleted reservoir levels.
"Avoid extended showers or having taps running when brushing your teeth or washing vegetables and so on.
"Water of lawns, we feel that it's no harm to let the lawn get a tan at this time of year. The grass will recover quickly."
