Sensaphone spot water detector
Crutchfield Customer Review (What's this?)
Excellent product. This one has been added to a system that has been in place for 9 years to provide notification of water on a basement floor in a second location by wiring the added detector in series. I would highly recommend this family of Sensaphone products.
Pros: Simple plug and play and more detailed instructions are on line. Sensaphone phone support is also easy to get.
Cons: Adding in a second detector requires you to understand basic low voltage wiring, specifically what "in series" means. An added sentence of explanation beyond "Wire the second detector in series" would be enough for the novice.