Water restrictions are likely to continue for several days in many places around the country as local authorities try to mend burst pipes and restore water levels.
Water tankers and standpipes are being provided for the areas worst affected.
Details of emergency supplies and restrictions are being published on local authority websites.
Hotline numbers have been set up in several areas to offer advice to householders in urgent need of water.
Colin Gallagher, Senior Executive Engineer in Fingal County Council, said supplies are critically low in the Dublin region due to unprecedented demand.
"The Dublin region is suffering a lot," Mr Gallagher said.
"There is a lot of water being used out of storage and our storage is depleting fairly quickly.
"We have had to introduce restrictions (in order to) maintain control of the system and not to lose the reservoirs completely."