Local authorities around the country are putting water restrictions in place as the thaw has led to widespread disruption to supplies.
The water shortage - due to a series of burst water mains - comes as Mét Éireann warns of flooding and heavy rain nationwide.
The Department of the Environment is asking property-owners to check their houses and businesses for leaks.
Counties Cork, Dublin, Galway, Kerry, Kilkenny, Kildare, Laois, Limerick, Sligo and Westmeath are all experiencing some disruption to supply.
In Cork, Cork County Council is experiencing record high flows from all reservoirs due to a large number of burst pipes following the cold spell.
Parts of Cork city, mainly on the northside, will be without water.
There are reductions in water pressure on the southside of the city.
Dublin City Council says there are restrictions on supplies and pressure across the Dublin region since 6pm.
The council says 60 million litres of water were lost in the capital region last night as a result of the thaw.
South Dublin County Council has announced that it is shutting down water supplies in Lucan and North Clondalkin until further notice.
Households will experience loss of supply because of burst water mains across all four Dublin Authority regions.
In Kildare and Wicklow, households will experience a loss of supply because of burst water mains.
The council says its crews are working as quickly as possible to restore water and it has appealed to people to conserve water.
In Westmeath, the council has said that it may be necessary to implement emergency shut offs without warning in order to ensure that reservoir levels are maintained and to facilitate repairs.
Water has been shut off in the Kinnegad area to facilitate repairs.
There are also reports of a burst water main at The Batteries Water Tower in Athlone which has resulted in a major loss of water to the Athlone area.
And a major leak in a in the Lynn area of Mullingar is causing water outages or reduced water pressure.
Sligo County Council has appealed to householders and businesses to limit water usage to essential needs only.
Ongoing restrictions will apply in Rathscanlon, Moylough, Curry, Ballymote, Gurteen, Skreen, Easkey, Rathlee, Enniscrone, Culleens, Corballa, Strandhill, Ballintogher, Mullaghmore, Maugherow, Moneygold, Collooney, Ballisodare and Aughamore areas.
In Limerick, extensive disruptions to public water supplies are expected in Abbeyfeale Town and surrounding areas and also the Ballyneety and Caherconlish.
The disruption is the result of major water main bursts
overnight. Further disruption throughout the county is likely as the thaw continues.
Clare County Council says overnight water supply will be cut-off until further notice at the following times and locations.
Doora, Barefield, Crusheen, Lahinch Road and Shanaway Road (from 11pm to 7am)
Shannon, Newmarket on Fergus, Sixmilebridge, Kilmurray, Kilkishen, Quin and Tulla (from 8pm to 8am)
Clonlara, Shannon Banks and Westbury (from 8pm to 8am)
Lahinch, Liscannor, Lisdoonvarna, Doolin and Fanore (from 11.30pm to 8am)
In Kilkenny, the council will have water available for collection from a number of hydrant stand pipes in Kilkenny City.
Kilkenny County Council will be operating an emergency call centre to deal with water related issues on Tuesday 28 and Wednesday 29 December from 10am to 5pm. The number to contact will be 056-7794145.
In Kerry, water supplies have been cut to over 20,000 people in and around Tralee due to low levels at the reservoirs which supply the town.
Kerry County Council is appealing to people throughout the county to conserve water and to switch off taps which may have been left on during the recent cold-spell.
The council says it will review the situation at 4pm but further curtailment of services may be required including cutting off water over the next number of nights.
In Northern Ireland, bottled water is being made available at a depot in Craigavon, Co Armagh, from 11am for anyone who has been without a mains supply for 24 hours.
Belfast, Dungannon, Omagh, Armagh, Newry, Derry and Craigavon are the worst affected.
For Further information check your local council website
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