Update 10.15pm:78,000 homes and businesses remain without power tonight.
The ESB say 306,000 have now been reconnected with priority given to emergency services, hospitals, water and waste-water plants.
All hospitals are now back on the grid and generators are being shared among farmers badly hit by loss of supply in the south of the country.
Senan Colleran from ESB Networks says crews are making real progress.
He said: "By Saturday we will have about 90% of our customers restored. We are now dealing with smaller and smaller faults and this effort will continue for many more days.
"Likely into early next week, into Monday and Tuesday of next week."
5.15pm: #Ophelia: ESB publishes estimated times of power restoration for remaining 105,000 customers
The ESB has said that power has been restored to 280,000 homes and businesses after storm Ophelia.
They said around 2,500 ESB Networks staff and 1,000 contractors are continuing to bring back power to the remaining 105,000 customers, and have been joined in their efforts by 283 staff from electricity utilities in Northern Ireland, Scotland, England, Wales, the Isle of Man and France.
The power firm has also published estimated restoration times on their PowerCheck app and online at www.esbpowercheck.ie for homes and businesses still without power.
Up to 25,000 people have no water supply.
Telecommunications company eir says that around 60,000 customers are without broadband, telephone and mobile service.
4.50pm: #Ophelia: Thousands remain without power and water as Met Eireann issue rainfall warning
Met Éireann has issued a new rainfall warning, covering a total of 14 counties, and predicting that accumulations between 30 and 50mm are possible tomorrow.
The Status Yellow Rainfall Warning applies to Munster, Dublin, Carlow, Kildare, Kilkenny, Louth, Wexford, Wicklow and Meath.
The warning comes as it emerged Cork city Council are to issue a flood alert for Cork City centre with heavy rain and high tides expected between 5.30pm and 7pm on Friday.
The news has prompted warnings from The National Emergency Co-Ordination Centre that repairs to electricity and water supplies may be disrupted and prolong the disruption of some of the thousands of customers who remain cut off from electricity, water and tele-communication services.
The chairman of the National Emergency Co-Ordination Centre, Sean Hogan, has this afternoon paid tribute to all those who have contributed to the clean-up effort after Ophelia and urged neighbours to continue to check up on vulnerable people.
Updated 4pm: A flood alert for Cork City centre is due to be announced soon.
Heavy rain and high tides are expected between 5.30pm and 7pm on Friday as Storm Brian approaches in the wake of Hurricane Ophelia.
Cork City Council said: "Flooding is possible at Morrisons Island, South Terrace and Wandesford Quay from 5.30pm to 7.30pm on Friday due to high tides."
They also warned that although wind speeds won't be as high as during Storm Ophelia, there is still a risk of further wind damage tomorrow and Friday due to the fragile status of trees and damaged buildings after the recent storm.
Update 1pm: With over 70% of impacted customers now reconnected, ESB networks have said that is expected that the majority of the remaining 119,000 customers will have their power restored in three to four days but some customers in isolated pockets will note be restored until Tuesday.
The latest ESB update comes as the National Emergency Co-Ordination Centre said it fears repairs to electricity and water supplies may be disrupted by Storm Brian, which may bring gale force winds this weekend.
In a statement this afternoon ESB networks said all available resources from ESB Networks are being deployed to carry out repairs to the network and restore power.
It read: "Crews from less impacted parts of the country are now on site in southern counties assist colleagues in the worst impacted areas. About 2,500 ESB Networks staff and 1,000 contractors have restored power to 166,000 homes and businesses, approximately 70 percent of customers impacted by the storm.
"Crews are continuing to work on restoring power to the remaining 119,000 customers, and have been joined in their efforts by staff from electricity utilities in Northern Ireland, Scotland, England, Wales, the Isle of Man and France."
ESB Networks have also published estimated restoration times on their PowerCheck app and website for customers who remain without power.
The statement went on: "ESB Networks acknowledges that this is a difficult time for our customers without supply and we are working as quickly as possible to restore supply to everyone.
"Having assessed the extent of damage to the network in the given area, these times are the best available estimation by our engineers and network technicians of when electricity supply will be restored. It is an estimated timeframe and is subject to on-going review and change."
Meanwhile, according to Irish water an estimated 56,000 customers remain cut off form the country's water supply.
The company's crisis management team will update the National Emergency Coordination Group later today.
Most of the water plants still affected are in the south of the country in Cork, Kerry and Waterford.
Margaret Ashwood of Irish Water told RTE that efforts will continue throughout the day to restore supply.
Initially there were 260,000 customers at risk of running out of water. This has been reduced to 56,305 #Ophelia— Irish Water (@IrishWater) October 18, 2017
Eir have also revealed this afternoon that an estimated 85,000 Customers are without broadband, telephone and mobile services across the country.
The company said they expect the number of customers without service will continue to reduce today as power supply issues are resolved.
In a statement they warned, however, that the number of individual line fault reports will rise today and over the coming days and that given the overhead nature of the network in rural areas, the damage is extensive and repair work will take time.
"Approximately 1,200 staff will continue to work today to assess and repair network damage. Field technicians have, as a priority, attempted to make safe any dangerous poles or cables that have posed a public safety risk. There have been close to 400 reports of dangerous plant since Monday."
Customer help and information resources:
ESB Networks are providing updates on all power outages and have assured customers that they can find estimated restoration times for their outage via PowerCheck
Irish Water are providing updates on water outages at water.ie
Eir customers can find updates via eir.ie and are encouraged to log faults on the “Log a Fault” section of the website or through our automated customer service line 1901. Faults can be reported to either service 24 hours a day, seven days week.
Update 12.13pm: Concerns repots may be impacted by bad wetaher
The National Emergency Co-Ordination Centre has said that repairs to electricity and water supplies may be disrupted by Storm Brian, which may bring gale force winds this weekend.
The strong winds, heavy and possibly thundery rain, will arrive on Friday and linger on into Saturday.
For today, Met Éireann has issued a new Rainfall Warning, covering a total of 14 counties.
The Status Yellow Rainfall Warning for Munster, Dublin, Carlow, Kildare, Kilkenny, Louth, Wexford, Wicklow and Meath was issued at 10am today.
The warning states that "heavy rain is expected with accumulations between 30 and 50 mm possible".
The warning is valid from midnight tonight until a minute before midnight tomorrow.
Update 10.45am: ESB spokesperson warns that restoring power will be slower as priority given to water treatment plants
With an estimated 130,000 ESB customers and 48,000 water customers still without supply the ESB's Head of Corporate Affairs has warned progress at restoring power may now be slower as priority will be given to water treatment plants and waste water treatment plants.
Speaking on RTÉ's Morning Ireland, Bernardine Maloney said the majority of affected customers are in Co Cork and went on to reveal that more than 255,000 customers have had their power restored over a 36-hour period since 4pm on Monday.
"As we go beyond today it's premises by premises and field by field, tree by tree - which is going to be a lot more slower progress.
"Really good progress has been made in the last 36 hours but the slower, more difficult, more rural, more isolated areas are what's remaining beyond today really."
ESB Networks have said significant progress had been made in counties Kerry, Laois, Galway, Clare and Westmeath and that priority is being given to the restoration of supplies for water and communications services.
ESB Networks are providing updates on all power outages via PowerCheck
Irish water are providing upadtes on water outages at water.ie
Update 9.11am: Estimated 130,000 households still without power while 48,000 have no water
An estimated 110 - 130,000 eir customers are still without service as the Southwest and Midlands continue to be the worst affected areas.
Approximately 1,200 eir staff are working today to assess and repair network damage.
"Field technicians have, as a priority, attempted to make safe any dangerous poles or cables that have posed a public safety risk," the company said
The company said County Cork is the worst affected area.
"If damaged infrastructure is causing a public safety risk, we ask people to contact us at 1850 245 424 or contact An Garda Siochana," eir added.
ESB Networks are providing updates on all power outages via PowerCheck
Earlier: Thousands of people remain without electricity and water in the wake of Storm Ophelia.
ESB crews are continuing their work to restore power after the worst storm to hit Ireland in more than 50 years.
The repairs are under pressure as Storm Brian is predicted to bring gale-force winds this weekend.
Three people lost their lives during the storm and more than 100,000 households are still without power this morning, while 48,000 homes have no water.
Sean Hogan, Chair of the National Emergency Coordination Group said ESB Networks is acting in a 'planned and methodical way'.
"Those who are without electricity can be assured that ESB Networks are working in a planned and methodical way tor reduce this figure on a daily basis," he said.
"They are also prioritising people with medical needs and critical infrastructure, including water supply," Mr Hogan added.
Updates on esbpowercheck.ie
Help is being drafted in from France and workers have been commended by the Taoiseach for their efforts to get the country back on track.
Children and teachers across the country are heading back to school after a two-day closure.
Bus Éireann said it is resuming over 6,000 school transport services this morning.
It added that little or no disruption is anticipated.
LUAS operator Transdev said the Red and Green Lines are back in operation.
The tram service was not expected to resume until later this morning following storm damage.
The decision to re-open the lines came after a test of track and technical systems last night.