Restrictions on water supply will be in place across the greater Dublin area between 8pm on Tuesday until 6am on Wednesday.
Irish Water has said there are more than 23,000 people with no water supply and 39,000 with water restrictions.
Restrictions were put in place across Dublin and neighbouring counties on Monday night and Tuesday morning and are expected to continue for a number of days following Storm Emma. Hospitals will be prioritised and will have water diverted to them.
Irish Water said the condition of pipes, particularly in Dublin where the average age is 80 years, had contributed to the widespread outages and restrictions across the country.
Speaking at the National Emergency Co-Ordination Centre, managing director of Irish Water Jerry Grant said “this is not a programme that will end today or this week”.
Irish Water said those currently without water are in Galway, Leitrim, Wexford and Tipperary. Those with a restricted supply include areas in Cork, Galway, Kildare, Leitrim, Mayo, Kerry and Meath.
More than 14,000 people are on storm related Boil Water Notices, including homes in Aughrim in Co Wicklow and Enniscorthy in Co Wexford.
Mr Grant said the shorter timeframe of 8pm to 6am to restrict water was to ensure “people will have water at breakfast”.
He also apologised for those in the greater Dublin area who did not have a water supply on Tuesday morning.
“When you do this kind of exercise, properties in particular areas do not get supply back instantly and it can take some time to recover,” he said.
Mr Grant said over the last three days, Irish Water has suffered a deficit of 111 million litres of water.
He said the utility had no option but to “to maintain restrictions until we not only eliminate the deficit but get that storage back to a safe and acceptable level”.
He said the restrictions on Monday night and Tuesday night “hit people hard” while some of the impacts “were not predicted”.
“I want to acknowledge at this stage communities that are still without water have suffered enormous social impact,” he added.
“It’s been really difficult for people for four or five days now to do without water and the criticality of drinking water in particular is really emphasised in places like Gorey and parts of Wexford.”
Irish Water said its crews have been mobilised across the country to make the “necessary repairs” at plants while “significant progress is being made”.
The utility said in Dublin three major bursts in the North Docklands, Infirmary Road and Skerries were wasting the equivalent of the daily water usage of Balbriggan which has a population of about 25,000. These have now been repaired.
In Donegal, normal service has been restored to 46,000 people after county council staff carried out repairs in the area. Services have also returned to normal in Kerry, Westmeath, Laois and Longford.
Due to hydrocarbon contamination of the source supplying the Fethard public water supply, Irish Water and Tipperary County Council, in consultation with the HSE, issued a “do not drink” notice for 12,000 customers supplied by this scheme.
“We are working with Tipperary Co. Council to resolve the issue but it is expected to stay in place for a few days,” Irish Water said.
Irish Water continues to appeal to customers across the country to conserve water at this time. The utility says water tankers will be provided to assist customers in affected areas with further details on the Irish Water website.
The Irish Water contact centre is available on 1850 278278 for customers to report outages. Customers are urged to report loss of service or visible leaks to assist Irish Water to identify bursts.
