Homes and businesses in Lancaster are without water after a pipe burst in Church Street.
Water company United Utilities said it had sent an engineer out to deal with the problem but it was taking longer than usual due to buried valves.
There have also been reports of electricity outages in the city centre and some businesses have had to close temporarily.
Fire crews have been called to the scene to help.
A spokeswoman for United Utilities said: “Our engineer is on site at present working to isolate the burst water pipe on Church Street.
“This is taking us a little longer than usual because some of the valves we need to access have been tarmacked over and we are having to dig them out.
“We have had reports of no water from 12 customers and we have a water tanker on the way to pump water into the mains and help restore water pressure.
“We’re very sorry for the inconvenience and we will restore supplies as quickly as we can.”