I use the Water Siren Plus in conjunction with an automatic dialer to alert me to the presence of adverse conditions in a second residence. The package instructions indicate that you can use the Water Siren Plus in two ways. You can either place the unit directly on the floor or you can detach the small sensor part from the main unit and locate it in a hard to reach area (there is a wire that connects the sensor to the siren unit). Since I did not have a hard to reach application, I opted to place the entire siren unit on the floor. By the time I was able to respond to an alarm condition, there was already 1 inch of water on the floor. The Water Siren electronics were fully submerged and shorted out. To the credit of the Water Siren Plus, it performed as it should and I was able to respond to a bad situation that would have been much worse had I not been alerted. Also, I was able to clean up and dry out the shorted out unit and it returned to full operation. However, since the unit was powered when it shorted out, many of the connections are corroded and can not be trusted long-term. This recent purchase is for a replacement unit. I have taken caution from my experience and detached the sensor from the siren unit so that I could place the siren unit that contains sensitive electronics in a spot where it will not get wet. In the meantime, the small sensor sits on the floor, remaining vigilant in its never ending watch for water.