Belfast, Northern Ireland (CNN) -- Northern Ireland's water supply is in a "precarious position" after several major water pipes burst, allowing 10 million liters of water to drain from Belfast reservoirs each day, the Northern Ireland Water interim chairman said Friday.
The state-funded water company's response to the "unprecedented situation" was "unacceptable," Padraic White said.
Tens of thousands of homes and businesses have lost their supply after frozen pipes burst in a rapid thaw that followed record low temperatures last week.
Many customers have been without running water since Monday, but some say they haven't had supplies for 10 days.
Pipes at the country's top hospital, the Royal Victoria Hospital in Belfast, were among those that failed, White said.
Water service might not be fully restored until the middle of next week, but even then hundreds of rural homes could still be without water, he said.
The water company's emergency call center was not prepared to handle "a disaster of this magnitude," but communication with customers will be improved, White said. He recommended a full investigation into the company's problems.
Northern Ireland Water has been heavily criticized for its response to the crisis, with some politicians calling for top officials to resign.
Chairman White said company executives were not considering resignations, since their focus at the moment is restoring water service.
The company said Friday that there had been an improvement in the situation in the past 24 hours and that the number of customers without water was down to around 5,000. It added, however, that as many as 24,000 customers could experience intermittent disruption to supplies as repairs continue.
Northern Ireland Water has blamed the problems on a rapid thaw, with a huge number of pipes bursting after a dramatic change in temperature -- from minus-16 to 10 degrees Celsius (3 to 50 degrees Fahrenheit) "within a matter of hours."
Company officials have also complained about a lack of investment in the water infrastructure over the years.
The Republic of Ireland has also experienced problems with its water supplies. The government said Thursday night that most parts of the country would see a resumption of service within two days, but restrictions in the capital, Dublin, were expected to remain in place until January 10.