A burst water pipe on the A54 Oakmere Road in Winsford has left homes and businesses in the CW7 area without water.
Motorists are experiencing severe disruption, with the A54 closed between the B5074 Swanlow Lane junction and the Browning Way junction.
The leak was reported to United Utilities shortly before 6am this morning.
A team of engineers is on site working to repair the emergency burst and tankers have been moved to the area to pump water into the pipe network to keep water flowing to as many people's homes as possible.
A spokesman for United Utilities said: "We're very sorry for the problems our customers are having with their water supply in the Winsford area today.
"We appreciate this is inconvenient for many people, but please bear with us while we carry out this repair and get things back to normal."
Winsford Academy was forced to send its pupils home this morning as a result of the incident.
Headteacher Andrew Taylor-Edwards said: "We have no water and no indication as to when the issue will be resolved.
"All students to report to school as usual on Thursday (October 9)."
Cheshire West and Chester Council's Winsford customer service centre Wyvern House is also without water, while Winsford Lifestyle Centre and Knights Grange Gold Club are reporting low water pressure.
