Moisture sensors

[Dave Smith]

Has anyone here ever setup a sensor under Linux to detect moisture or 
some other anomaly in the home or office? I own a pretty old house and 
have had the basement flood a couple times, for differing reasons. The 
flooding wouldn't be a big deal if we could catch it early, so I'd like 
to setup a few moisture sensors around the basement's most worrisome 
areas (toilets, drains, etc), and hook them up to a 
"Linux-box-in-the-closet" to alert me if moisture is ever detected. 
Anyone have any ideas?

--Dave