More than 600,000 people will have to continue to boil their water until at least Tuesday due to ongoing problems at the Leixlip Water Treatment Plant.
The Environmental Protection Agency (EPA) and HSE carried out an audit of the treatment plant yesterday and made the decision to keep a boil water notice in place as more work is required to ensure the water is safe to drink.
This latest incident, which is the second boil water notice in recent weeks, has impacted households and businesses across parts of Dublin, Kildare and Meath.
Minister for Housing, Planning and Local Government Eoghan Murphy said he was "extremely disappointed" that a precautionary boil water notice must remain in place.
Speaking in Cork, Mr Murphy said: "It is a precautionary boil water notice and it was put in place because the only other alternative was to turn off the water altogether and that would’ve been far worse for people in terms of being able to go about their daily lives.
"We hope to be able to lift it as soon as we can but that is determined by the HSE and the EPA."
Work will continue over the weekend to restore supply and further test results should be available on Tuesday.
Niall Gleeson, Managing Director of Irish Water, apologised to those impacted for the inconvenience.
He said Fingal County Council have flushed the network in key areas to remove the remaining at-risk water from the network.
“We are aware that the old plant at Leixlip is vulnerable and Irish Water, working with Fingal County Council, have worked to maximise the processes at the plant and increase the monitoring and staffing.
"Irish Water, working with Dublin City Council and Fingal County Council, will work to move additional water through the system towards Leixlip to take the pressure off the old plant. The ultimate solution is to replace the filters at the old plant and this process is being accelerated as quickly and safely as possible while still maintaining supply to the greater Dublin area.”