A million and a half homeowners had their water restricted last night thanks to the selfishness of a few thousand users who leave their taps running to prevent pipes freezing.
Water supply and pressure was reduced in all Dublin homes from 7pm last night to 7am this morning due to a severe shortage.
Elsewhere, counties including Cork, Galway, Kerry and Waterford also faced water rationing.
More than 1.6 million people will be hit with cuts in their water supply for the next three days because of record demand on the system.
Dublin City Council last night said it would reduce pressure across the city, also to happen in counties Wicklow and Kildare, from 7pm to 7am until at least Friday because of widespread shortages partly caused by people leaving their taps running.
The move will result in a small number of homeowners and businesses being cut-off, a spokesman said, but the move was necessary to conserve stocks.
The shortage of drinking water is now acute across the State. Almost half of the country's local authorities are restricting supply amid fears that unless access to water is rationed the situation may become critical.
The shut-off came as weather forecasters predicted the Siberian blasts -- along with more snow -- would return with a vengeance next week just in time for Christmas.
After a temporary respite over the weekend, Met Eireann forecast that sub-zero temperatures will return from next Monday.
"Sunday night will be very cold with widespread frost and Monday night even colder with air temperatures below zero in most parts," the Met Office said.
A weather expert who in mid-November predicted Ireland's big freeze said it would get even colder next week -- with a "once-in-a-lifetime" Siberian weather event bringing -10C temperatures, six inches more snow and a white Christmas.
Meteorologist Brian Gaze had issued a weather warning on November 16 for a cold snap lasting over a week with -8C temperatures.
The long-range forecaster, of independent company The Weather Outlook, has now predicted that next week will be even colder as the freak cold spell stretches to a month to last beyond Christmas -- something he claims we will never see repeated in our lifetimes.
Bookmakers are offering odds as short as 7/2 for a white Christmas in Dublin.
Road conditions were again dangerous in many parts of the country yesterday with numerous collisions reported.