Householders have been urged to take simple measures to save water, with severe water shortages predicted across the country.
Reservoirs were ordered to shut down in Clare, Donegal and Wexford as they hit critically low levels while supplies were “throttled”, or slowed down, in Dublin and other cities.
After the latest Government emergency response meeting, Minister for Transport Noel Dempsey warned more restrictions would follow if householders do not start conserving water.
“The big message is the danger to water supplies in various parts of the country,” he said.
“The fact that people are using water, leaving taps running and so on, is causing serious, serious depletion of water stocks.”
Burst and frozen pipes in areas still not covered by the thaw are also contributing to the shortages.
“If it continues, if people don’t conserve the water, it will inevitably lead to cuts in water supply to different areas,” said Mr Dempsey.
Tankers have been deployed in some of the worst hit parts of the country so as people have access to fresh drinking water while people with supplies have been urged to cut usage with practical measures like taking shorter showers.
Clare County Council said it has been forced to halt public water supplies overnight in Scarriff, Tuamgraney, Tulla, Sixmilebridge, Newmarket on Fergus, Shannon Town, Cratloe, Bunratty, Kilmurray and Kilkishen where reservoirs were rapidly running dry.
Usage soared in the county by about 20 per cent as people left taps open in attempt to stop their pipes freezing over.
Supplies were also being shut down in parts of Ennis from 11pm to 6am to improve flow to some badly-affected parts of the town.
Restrictions were also placed on Ennistymon, Liscannor, Lahinch, Lisdoonvarna and Doolin.
In Dublin, where usage reached at an all-time high at 25 per cent above normal levels, authorities sent six tankers onto the streets to ensure water was available to the worst-hit parts.
Senior executives from the capital’s four city and county councils met with Kildare and Wicklow county council officials for crisis talks during the day.
Afterwards, a Dublin City Council spokesman said there was no immediate plan to shut off or “throttle” public supplies, but he urged householders to conserve water where possible.
“We would appeal for people to only use washing machines on a full load, use dishwashers sparingly, take shorter showers and not to leave taps running when brushing your teeth or filling the kettle.”
The council has warned that if people did not conserve water, pressure may have to be reduced and supplies may have to be reduced overnight.
Fingal County Council said it will be 'throttling' water supply from today. Water supply will not be cut off completely but all areas will experience reduced pressure and there may be a disruption to supply during the day or at night over the next couple of days.
Cork city manager Joe Gavin said supplies to key buildings like the Mercy Hospital were being affected by low pressure across the water network.
Supplies were restricted in several parts of the city with stand pipes set up in some areas for emergencies. There are severe water shortages in Bantry and in Allihies due to the cold weather. Water will be available at 21 fire stations throughout the county to householders today between 10am and 4pm.
Extremely high demand and burst pipes in Donegal has left a number of areas, including Falcarragh, the Rosses, Gweedore, east Inishowen, Lifford, Castlefinn, the Frosses and Inver, without running water.
Reservoir supplies were being shut down overnight in the worst-affected areas, said Donegal County Council.
In Sligo, major pipe bursts hit both the north and south of the county while in neighbouring Leitrim, council chiefs said supplies may have to be turned off in some parts overnight.
Similar warnings were issued in Meath, Kildare, Limerick and Westmeath.
Galway city and county councils are still reiterating appeals for conservation of water and predict that the severe weather will continue to affect the region for several days.
Meanwhile, Minister for Education Batt O'Keeffe today rowed back on an earlier instruction to schools not to open until Thursday due to adverse weather conditions.
Mr O'Keeffe said schools in a position to open tomorrow should now do so.
Following a review of weather conditions, Mr O'Keeffe said he had decided the normal arrangements that see the schools decide to open or close based on local circumstances should be reinstated.
Additional reporting: PA