Further water restrictions for the Greater Dublin Area are due to come into force from 10pm this evening.
Homes and businesses will have a reduced supply for seven hours every night, from 10pm to 5am.
Night time water restrictions are already in place in several counties, and Irish Water has said the restrictions could be extended to other parts of the country.
The restrictions come as several weeks of drought have led to low levels of water supply.
Irish Water has said that even though rain is expected this week, it will not be enough for water sources to be replenished.
There will be 34 areas around the Greater Dublin region that will experience a reduction in water pressure.
New night-time water restrictions come into force in Dublin tonight pic.twitter.com/421GS0cVKM— RTÉ News (@rtenews) July 16, 2018
While most households will not lose supply, Irish Water says supply for some customers on higher ground and at the remote end of networks may be reduced to a trickle.
Areas around major hospitals have been protected and pressure will not be affected.
Irish Water says the restrictions are necessary to protect supply and avoid widespread shortages in the autumn.
It says it is impossible to know yet how many litres of water would be saved per night as a result of the curtailments.
The restrictions will initially be in place for a week but there is the high possibility that they will be extended.
The following areas will experience low pressure overnight:
City Centre, Smithfield, Phibsboro, Drumcondra, Cabra, Whitehall, Finglas, Beaumont, Marino, East Wall, Inchicore, Crumlin, Ballyfermot, Kimmage, Walkinstown, Chapelizod, Ranelagh, Rathgar, Ballsbridge, Donnybrook, Sandymount, Ringsend, Clondalkin, Lucan, Tallaght, Templeogue, Ballyboden, Rathfarnham, Dalkey, Killiney, Ballybrack, Shankill, Cabinteely and Bray
The head of an organisation representing publicans has said members are very concerned about the potential impact of the water restrictions on their trade.
Donall O'Keeffe of the Licenced Vintners' Association said the weekend is a critical period for the night-time economy and he called on Irish Water to ensure there are no restrictions in place for publicans during this period.
He added that LVA members pay between €5,000 and €6,000 for water a year.
Irish Water has said it will be monitoring the water restrictions very closely every night and every morning for a week to understand how much water is being saved and how customers are being impacted.
The company's Corporate Affairs Manager, Kate Gannon, said that while they cannot guarantee that nobody will feel a reduction in supply or experience an outage the company has done all it can in terms of automating the pressure and looking at critical monitoring points and modelling the water system in the background to ensure people do not experience water outages.
Irish Water said if people do experience water outages they want them to contact the company so that amendments and adjustments can be made.
She said it is impossible to say how long the night-time restrictions will be in place in Dublin and that it all depends on the weather, as well as the results of public water conservation efforts for which they said they were grateful.