Thousands of residents have had their water supplies cut off after a main burst.
Severn Trent Water said it had no time scale for when more than 20,000 people would see their supply fully restored, following reports of low pressure or no water at all.
The provider said the problems affecting homes to the north and east of Nottingham had been traced to a pipe which burst today in the village of Epperstone.
In a statement on its website, Severn Trent said: "We've managed to get some people back on supply following this morning's burst pipe in the village of Epperstone, north of Nottingham, but there's still more to do.
"Due to the size of the water pipe affected, a lot of villages and towns in the area have been affected by the issue and left without water.
"We believe the affected areas include Radcliffe on Trent, Bingham, East Bridgford, Upper Saxondale and Flintham, and we'd like to apologise to everyone who's had problems this morning."
The company said that it was looking at other ways to get water out to residents, particularly what it described as "our most vulnerable customers".
Severn Trent said concerned residents can contact the company on 0800 783 4444 or tweet @stwater.
Meanwhile, customers asking online how long supplies might take to be restored were being told by the provider through its Twitter account: "I cannot give a time scale - we are looking at all options for getting customers back on supply."