Moisture / Water probe

["markttay" <markttay@xxxxxxxxxxx>]

I have a basement in my new build and have had a number of problems
recently that have led to some flooding - nothing major, but enough
to
worry me that I could come back from holiday to a swimming pool
rather
than a dry basement.

I am looking for an probe that will detect the presence of water in a
channel in the basement floor, the signal from which I can use to
shut
off the water main or take other action.

Anyone know of such a probe/sensor?
Thanks