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, Transport Minister 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 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 around 20 per cent as people left taps open in attempt to stop their pipes freezing over.