How much water does it take to set off the alarm? Michael T October 20, 2020 19:07 Updated Water is detected at 1mm of accumulation. Related articles Sensor Details and Specifications How loud is the audible alarm? Where are the best places to use the SimpleSENCE® sensors? How do I know if a sensor is connected? What does the "Device Offline Detected" alert mean? Comments 0 comments Please sign in to leave a comment.