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Water Level Sensor

Interleaved traces whose reading rises with how deep the water is.

How it works

A water level sensor has a set of interlocking conductive traces. Water bridges them and lowers the resistance, so the analog output climbs as the water rises — useful for tank levels, rain, and leak detection.

The exposed traces corrode if left powered in water, so a good trick is to power the sensor from a digital pin and only turn it on for the moment you take a reading.

Pins

+ (VCC)
Power — often driven from a digital pin.
− (GND)
To GND.
S (signal)
Analog output — to an analog pin.

Ratings

Voltage
3.3–5 V
Output
Analog (rises with water)

Tips

  • Power it from a GPIO and switch it on only to read — greatly reduces corrosion.
  • Calibrate dry vs. submerged to pick a threshold.