Police are appealing for information after a hosepipe was put through the letterbox of a house in Skipton Road, Earby, and turned on flooding the property.
The incident occurred some time between Friday and Monday and it is thought the hosepipe was on for two days.
Sgt Shaun Pearson said: “At the moment we are not sure whether this is an act of stupidity or a malicious act against the property owners.
“It was only noticed when water began to enter a neighbour’s cellar. It is too early to say what the damage will amount to but it could be in the tens of thousands of pounds.”
Anybody with information should call police on 101 or alternatively contact Crimestoppers anonymously on 0800 555111.