More than 30 patients had to be moved from two hospital wards after a burst pipe caused flooding.
Freezing conditions led to the problems at Newcastle's Freeman Hospital in the early hours of Tuesday.
A hospital spokesman said two wards were partially flooded but that patient treatment had been not affected.
Most patients have now returned to the wards, although 15 beds are still closed while repair work at the hospital continues.
A spokesman for Newcastle Hospitals Trust said: "Staff acted quickly to evacuate the 32 patients from the wards.
"Work has progressed well and both wards are now open and patients have been moved back into the two wards - 15 beds remain closed.
"It is anticipated that further beds will reopen later. All planned and urgent activity is being accommodated.
"No patients have been affected, although we recognise they have had a disturbed night and now that they are back on wards they are being encouraged to rest."