Review on Floor Water Sensor Flood Detection by Dave Russell

This is a good water sensor to connect to the controller. I used it with an Arduino to detect a drain backed up when my washing machine drains. I used a relay and was able to pause the washing machine until the drain water stopped. The sensor detects quickly. I agree that it would be nice if the chord was longer, but lengthening it is easy enough. The included app notes are nice. You'll have to play with the value of the pull-up resistor you add to work with the standard TTL input pin.