This seems like a good concept. The water flood alarm is meant to sit on the floor near potential sources of flooding such as dishwashers and washing machines. The device sensors detect excess moisture and sound an alarm so that you are able to address the problem before your neighbours one floor down have to knock on your door asking you to explain why there is a continuous stream of water running down their dining room table.
As long as you make sure that internal battery is always charged, your dog doesn't think it is a new chew toy, you can keep the alarm in a place that doesn't get in the way and you actually know what to do with the appliance once the alarm goes off, this might be a worthwhile gadget.
Further information on availability can be found here