I have a couple of these Zooz Z-Wave water detectors. They were recognized by zwave2js, and easy to set up and test. My only issue is that I get triggers from them whenever the Z-Wave network changes - like, when I add new devices, I get an alarm from them.
They're tiny - like the size of an old box of (matchstick) matches. If they were cheaper, If put one under every sink.
I had a similar issue with other zwave sensors. With a little help I was able to refine my triggers so that my automations only run when they go from an βoffβ state to an βonβ state. Before that theyβd trigger from a βnoneβ or βunknownβ state, which is what happens when HA or zwave2js restarts.