Water bosses tonight faced demands to quit as engineers struggled to repair leaking pipes to tens of thousands of homes in Northern Ireland, amid fears the drinking water fiasco could develop into a major health emergency.
Lorries carrying 160,000 litres of bottled water are due to arrive from Scotland in a bid to ease the plight of families all over the country, many of whom have been without toilet and washing facilities since before Christmas, when temperatures were at their lowest in living memory.
The Stormont Executive will meet in Belfast tomorrow to discuss what extra measures are needed to deal with the worsening situation but questions are being asked about the performance of top staff at Northern Ireland Water (NIW), the company at the centre of the crisis.
It is expected to be at least a few days before all the repair work to burst pipes is finished and the system gets back to normal.
Supplies are being rotated, but tonight up to 36,000 customers were affected at any one time.
Conor Murphy, the minister in charge of the Department of Regional Development, who admitted serious failures in the public information process, is also under pressure.
People queuing with containers looked on in disbelief as tankers arrived empty at distribution centres in Belfast and Cookstown, Co Tyrone.
Mr Murphy said: "I can understand the frustration and anger, and lessons need to be learned."
Some families have had no running water for 11 days.
Glynn Roberts, chief executive of the Northern Ireland Independent Retail Trade Association said: "How come other parts of the UK went through similar weather conditions, but haven't suffered the drought we have? Heads should roll because of the disastrous reponse."
Outside Londonderry and Belfast, one of the areas hardest hit, almost 80 other towns and villages in all six counties have had supplies disrupted because of unprecedented demands on resources in the aftermath of the thaw which followed one of the coldest periods in living memory.
Some reservoirs are empty and others are worryingly low.
Unreported leaks in private and commercial properties which have been vacant over Christmas - including student accommodation, holiday homes and farm outhouses - have been blamed for draining much of the water.
NIW tonight claimed 95% of customers were getting water after supplies were increased to their highest ever level, up 40% from 600 million litres a day to 850 million. It was anticipated that interruptions would last between six to eight hours.
First Minister Peter Robinson and Deputy First Minister Martin McGuinness who will chair tomorrow's meeting at Stormont Castle confirmed they had accepted Scotland's offer of assistance but were furious at the delay in NIW getting its act together.
Mr McGuinness said: "People feel they were let down, and they were let down."
A joint ministerial statement said: "NI Water's response was clearly inadequate and we are now looking urgently at what further measures can be taken to alleviate the problems people are facing."
Civil servants have been drafted in to call centres in support of staff answering queries from the public. As many as 6,000 calls a day are being made, six times the average. Bruce Robinson, head of the Civil Service, also got involved to help with contingency arrangements, including plans to beef up communications.
Leisure centres were opened to provide showering facilities and additional sites for water bowsers and water distribution have been identified.
One hotelier on the north coast used sea water to keep toilets functioning but with NIW confirming it could be days before all supplies are restored, restaurants, bars and clubs fear New Year's Eve business could nose dive.
Red Cross staff, community workers and firemen are heavily involved and politicians on all sides have been out in their constituencies to help. Some took to the roads with car loads of water.
But with the onset of a winter vomiting bug, some doctors warned the crisis could quickly develop into a major health issue, especially among the elderly.
Dr Peter Maguire, a GP in Newry, said: "This is really now a public health emergency. Northern Ireland Water has been shambolic in their response. People with young families have not been able to flush toilets and wash themselves, never mind get access to drinking water. It's just not good enough. What's happening is really not acceptable."