Kemo m158 water sensor relay switch module 9 12v dc kemo m158 p this module has a very sensitive input for a pair of probes when the 2 probes come into contact with water a relay switches on which can be used to control sirens lights pumps etc p p the water sensors use an extremely low voltage in order to prevent the otherwise usual oxidisation through galvanic currents p kemo m158 water sensor relay switch module 9 12vdc