Northern Ireland's deputy first minister has said he feels "absolutely let down" by NI Water's handling of a crisis in water supplies.
He was speaking as 36,000 people across NI struggled to cope without running water - some for as long as 11 days.
Information is being provided on the NI Water website on when water supplies will be turned on - and cut off.
The interim chairman of NI Water admitted on Wednesday that its response had been unsatisfactory.
Meanwhile, the Scottish government is to provide 160,000 litres of bottled water.
A shipment from bottling plants in Banff and Forfar were loaded aboard the ferry to Larne on Wednesday evening.
Deputy First Minister Martin McGuinness said people had not been given enough information as to when water would be restored.
"My focus is on how NI Water can do things better over the course of the next number of days," he said.
Northern Ireland Water has said an unprecedented number of leaks caused by the thaw following a long period of freezing weather have been putting "big pressure" on its systems.
Mr McGuinness said: "Our concern has to be around the difficulties experienced by elderly people and young people with very young babies."
Northern Ireland Water is a government-owned company and is NI's sole provider of water and sewerage services.
On Wednesday afternoon, its interim chairman Padraic White said: "I don't think the response has been satisfactory, particularly in terms of conveying information to people."
He added: "The organisation has to improve its performance, has to improve its communication and I believe will improve its communication over the next two days or so.
"I empathise as interim chairman with those people who haven't had water for the last two or three days, that's an awful situation to be in.
"There is a reality that water is very low in the reservoirs and the expectation is it will gradually improve over the next few days."
Earlier, Regional Development Minister Conor Murphy said: "The big problems have been communication and the lack of information on the ground.
"People want certainty that they are going to get accurate information as to what is happening and to get water restored."
Executive ministers are to hold a meeting on Thursday to discuss the crisis.
Almost 80 towns and villages across NI have been affected.
Local councils are working to supply water and offer free showers to people without a mains supply.
NI Water said it was alternating supplies from reservoirs in a bid to give every area a limited supply, causing more interruptions.
Dame Joan Harbison, who speaks on behalf of older people, said many pensioners are struggling to cope.
"There are many older people throughout Northern Ireland who haven't access to water, who can't go to where the water is and certainly can't stand in long queues for long periods of time to actually get water," she said.
"I do think that the Public Health Agency and other health agencies need to get themselves organised to deal with what may actually become a health emergency as well as a water emergency."
Dr Peter Maguire, a doctor from Newry, has been living for eight days without water.
"This is really now a public health emergency. NI Water has been shambolic. Young families have been left without drinking water and not able to flush toilets. This is unacceptable.
"There are too many vulnerable people who are now without a water supply for over a week," he said.
"The situation is unprecedented, but now it is getting out of control."
Environment Minister Edwin Poots said NI Water was not properly prepared.
"Everybody knew that whenever the thaw came that there were going to be big problems with water, so I think that there was a lack of preparation by NI Water, particularly in the issue of communication," he said.
"I think that it's limited how much they can do, the engineers, the guys on the ground, they're just going to have to work their way through all of the problems. But in terms of communicating those problems with the community, they failed and failed very miserably."
Emergency centres have been set up across Northern Ireland to supply water. Leisure centres are also open to offer free bathing facilities.
Details are available from the NI Water website, or telephone hotline: 08457 440088, on Ceefax 169 and BBC News Online.
The Fire Service and the Red Cross have stepped in to help.
Worried farmers have been among dozens of people contacting the BBC about their water supply problems.
We have been without water for seven days. I have two young children, both under five, and it is proving exceptionally difficult to provide water for our family's needs, especially during a time when the whole family are at home. We contacted the emergency number a couple of weeks ago, when our water was off for three days. The water service did send someone out, but told us that as the mains pipe was frozen it was not their responsibility. Alastair McFarland, Ballinamallard
I would like to comment that despite your report citing Belfast and surrounding areas having severe problems that there are many people in the Dungannon and Coalisland area who have been without water for coming onto a week. Why have you failed to report this and why is this not considered enough of an emergency situation so that action is taken to distribute water as is being undertaken today in Belfast? No one I know can get in touch with NI Water to ascertain the action being taken to address this matter. Leontia Doran, Dungannon, County Tyrone
We have had no water since Christmas Eve, starting with the bath taps. We thought it was a frozen pipe at first, but then the taps downstairs stopped working too. Now we have no water at all, no shower or bath, can't even flush the toilets. Can't get through to Northern Ireland water as the number has been engaged all day and the website has been down most of today too. Claire, Dromore, Northern Ireland
We live in Coleraine and have no water. Can't get through on NI Water Helpline and their website keeps crashing. All local supermarkets and garages have sold out of bottled water and there doesn't appear to be any supplies available here from NI Water like there is in other towns. Total chaos. Tricia Roulston, Coleraine
We have had no mains supply for over 48 hours. Calling the emergency line is futile. To make matters worse supply of bottled water in local supermarkets has dried up. Johnny Bottomley, Bushmills
Our home has been without water since Christmas eve. The Housing Executive were informed early that morning and as yet no one has been in contact. We have been on the phone to NI Water constantly with no avail as it is either engaged or you are left waiting for the next available advisor, after 20 mins you have to wonder is there anyone there and give up. Other houses close by lost supply Monday night and it returned within a few hours; ours has had no such luck. There seems to be a serious lack of co-ordination and accountability. Gerry Andrews, Belfast
We live in Edenderry, Belfast and have no water in the village. I have tried in excess of 100 times to phone the Waterboard number. It is constantly engaged. Drove to North Belfast to get water for ourselves and an elderly neighbour to be told they had run out 10 minutes before we arrived! Heather Taylor, Belfast
Our water supply failed yesterday (Monday), morning. I called NI Water. I held on for 30 minutes before getting into the queue and then waited 10 minutes to speak to someone. The water supply was restored by the evening. However, considering the huge problem of such a deep freeze over the whole country, I accepted that there would be hundreds (in fact thousands) of people calling in. I am sure the NI Water got some things wrong, but on the whole they have done as good a job as could be expected in this extreme situation. Dr Raymond Cox, Portadown, Co Armagh
We are a family in East Belfast and have been without water since approximately 8.30am this morning. I took us until after 12pm to get through on the emergency water line and all we were told was that there was a problem with a reservoir, repairs were underway but there was no timescale to fix it. We cannot cook, wash, go to the bathroom etc and have no idea how long this will last for! Lisa, Belfast, Co Antrim