Work is ongoing to restore water supply to 4,500 customers after low pressure was caused to the system in the aftermath of a fire.
Residents and businesses in the Peterlee area have seen their water pressure levels affected since this morning.
Northumbrian Water said it became aware off issues at around 8.30am, with its engineers working to restore the service.
It has said 4,500 properties are affected by the issue.
A spokesman said: "There is an airlock in the water main after fire service workings and a power cut.
"We are working to restore supplies as soon as possible."
The problems follow on from an incident on the North East Industrial Estate in the town yesterday, where County Durham and Darlington Fire and Rescue Service used two jets and an aerial ladder platform to put out the blaze in a large factory unit.
Northumbrian Water can be contacted on 0345 717 1100.