If you do bear in mind there needs to be an actual "event" leading to the claim.
If you drive into water, user error. If you park below the tide line, user error. If it rains hard and your windows are open, user error.
If you did nothing wrong but have a blocked drain I would expect your insurance company would try and duck the claim as one of the following:
- a maintenance issue
- a design issue
- gradual process loss
