Large numbers of homes in Northern Ireland are likely to be without water for days to come, the national provider said, after a thaw in icy conditions caused pipes to burst.

Northern Ireland Water said 40,000 people were without running water in 74 towns and cities. Some families have been without water for eight days and are relying on bottled water being handed out at 18 centres.

Liam Mulholland, of NI Water, said the situation would continue for at least a few more days.

“Having clean drinking water is a very important aspect of life and we are trying to get that system back up and working as fast as we can,” he said.

“The sooner we don’t have customers going to stand pipes or alternative water supplies the better. This may go on for another short period but we are doing our best to keep it as short as possible to get those reservoir levels up and provide water to our customers.”

Mulholland said vacant properties with leaks that had yet to be traced and repaired were proving a drain on the system.

The NI Water website listed 74 conurbations as experiencing interruption to their water supply.

One GP affected by the shortage in Newbury warned that it could cause a health crisis.

“This is really now a public health emergency,” said Dr Peter Maguire. “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.”

Northern Ireland’s deputy first minister, Martin McGuinness, has promised a review of the response to the extreme weather. “The recent long spell of sub zero temperatures and snow falls, followed by a quick and dramatic thaw, has resulted in frozen pipes followed by flooding which has affected many people adversely, with some having witnessed considerable damage to their homes,” he said.

“I would like to thank public servants for their hard work over the this period of severe weather in seeking to help. I will be asking departments for their assessment of the situation and to bring forward proposals on how best to address, and deal with effectively, situations such as this.”

McGuinness repeated calls for keyholders to check unoccupied houses and businesses where leaks may have occurred.

The SDLP South Belfast MP, Alasdair McDonnell, was among several senior politicians who said the government was failing to handle the problems caused by the severe weather.

“People in South Belfast are at their wits’ end having been without water now for several days and many are currently having to cope with the nightmare of sewage in their homes with little help or reassurances from NI Water,” McDonnell said.

“Businesses in our busy retail area have also been damaged by this water supply nightmare which is proving particularly detrimental at this crucial time of the year for retailers. Residents also have the added frustration of not being able to get through to speak to anyone in NI Water or get any information on whether or not their water is being fixed, as the agency’s website is down.”

NI Water said it had been inundated by calls from the public and had dealt with 6,000 in the early part of yesterday alone.

The Housing Executive, which covers social housing and which also came in for criticism when homes were hit by heating problems during the cold snap, said it had received 2-3,000 calls a day about frozen pipes.