A simple water flood sensor (water level) detects electrically conductive fluid through 4 outlets on the detector body (spot detection). The sensor can be placed on a wall or floor with a dielectric surface.

Using an RJ11 cable, it connects directly to the 1W-UNI port (Poseidon, Ares, STE2, ..) where the sensor shows the values 1 (flooded) / 0 (non-flooded).