Passive water sensors

The water sensors for connection to the water detectors for fixed installation are passive sensors, i.e. they are essentially refined, low-corrosion cable ends.
A passive sensor does not emit a signal and does not change its properties when in contact with water.
Rather, it is the water detector itself that sends a signal in the form of a 120 Hertz square wave with 2.5 Vpp to one of the sensor contacts and "sees" what is returned on the other wire. If the sensor is dry, none of the square wave is transmitted to the other wire. However, if both contacts are in the same puddle of water, the square wave is sent back to the water detector via the water's conductivity. For water detectors from Elektrotechnik Schabus, the resistance must be below approximately 80 kOhm for an alarm to be triggered.
However, this also requires conductive water, i.e. water that is not pure, in which free ions move and which can therefore conduct electricity

Completely “normal” water, such as that which comes from our taps, which perhaps enters our house as rain, or which enters our boat as fresh water, always has sufficient conductivity.
Demineralized or distilled water, which usually also includes condensate, is generally not conductive enough to be detected by a water detector using a sensor.

Water sensors are only suitable for regularly dry environments and must not be used to measure water levels in shafts, tanks, pump sumps, or other containers. Mini float switches are always used to measure water levels or lifts. Water sensors are only suitable for floors, surfaces, etc., to quickly detect moisture, for example, under a washing machine.
Sensors that are submerged for extended periods of time will draw water in, resulting in frequent false alarms. Therefore, every water sensor is a wear part, and a defect is not covered by the warranty.