About 7,000 homes were twice left without water after pumps failed.
The supply was cut off to people in Bourne and the surrounding area on Sunday and Monday evenings.
An Anglian Water spokesman said: “We are very sorry that customers in Bourne and the surrounding area were affected with either no water or low water pressure on two separate occasions on Sunday and Monday evening.
“This problem was caused by an electronic failure at the booster pumps which feed the area. We’re investigating as a matter of priority why this has happened and are doing everything we can to prevent it from re-occurring.
“On both occasions our monitoring has alerted us to the problem and an engineer has been quickly sent to restart the pumps to restore supplies, meaning homes were affected for a few hours while pressure returned.
“We understand how disruptive it is to lose water supply in this way and are grateful for our customers’ patience and understanding while we’ve worked to return things to normal.”