Bests & Worsts Reviews from Amazon

I purchased this so that I would no longer be surprised by a backed-up floor drain in my basement. Once in a while, it would back up after using a moderate amount of water, rather randomly though. I tested this unit and it seemed to be exactly what I needed so I would not be surprised by a backup and I would be able to take action if it happened. A few days after putting it down, I was watching TV and I thought that I heard a single Beep. I listened but heard nothing else. I thought perhaps a smoke detector battery was getting low, but as I heard nothing else, I paid no attention. About an hour later I flipped on the basement light and was staring at an inch of water covering the floor, and there in the middle was the silent Honeywell RWD21 Water Leak Alarm. After clean-up, I did a bit of testing with the unit. If it TOUCHES water, you get the alarm. If any more than a surface trace of water is present, it will not work. Basically this renders it pretty useless for most applications where water may exceed 1/4 of an inch at a moderate pace. I could have clearly heard if there were more, but I had gotten only ONE warning beep. I have since purchased two very inexpensive units from China and have tested them. They emit an ear-splitting alarm when wet all the way through submersion. There are better items to spend your money on if you need reliable water detection.