I've been doing this for years, but my buddy saw it and had an A-HA! moment.
Sometimes if you have a floor that's not completely flat, the water on the floor might miss the water sensor. Or, if you have a vertical pipe and it leaks, it might leak down the opposite side of the pipe from the sensor. On a pipe, wrap a sponge around it, zip tie it, and then zip tie the sensor to the sponge. On a floor, use a rag or a towel to cover a larger area. Water will eventually wick over the sensor probes and set it off.
