Up to 10,000 homes and businesses lost their water supply on Tuesday morning after a power cut.
Customers in the Terrington and Fincham areas were left without power for an hour after a power cut at Anglian’s Water’s Marham station.
Pumps stopped working around 6.45 am after the system tripped.
But it was re-set by an engineer and everything was working again at 7.45pm.
An Anglian Water spokesman has apologised for the interruption in supply.
The station at Marham also supplies homes between Lynn and Friday Bridge, near Wisbech, but these were not thought to be affected.