The water level sensor / leak detection sensor is a 3-pin module that outputs an analogue signal (generally 0 to 500) that indicates the approximate depth of water submersion. When used in conjunction with a pull up resistor, it can be used as a digital device to indicate the presence or water.

The sensor has a series of ten exposed copper traces, five of which are power traces and five are sense traces. These traces are interlaced so that there is one sense trace between every two power traces. Usually these traces are not connected but are bridged by water when submerged.

The series of exposed parallel conductors, together acts as a variable resistor (just like a potentiometer) whose resistance varies according to the water level. The change in resistance corresponds to the distance from the top of the sensor to the surface of the water. The resistance is inversely proportional to the height of the water:

• The more water the sensor is immersed in, results in better conductivity and will result in a lower resistance.

• The less water the sensor is immersed in, results in poor conductivity and will result in a higher resistance.

The sensor produces an output voltage according to the resistance, which by measuring we can determine the water level.

Technical Specifications: 

• Operating Voltage: +5V
  
• Working Current : <20mA
  
• Sensor Type : Analog or Digital
  
• Water Detection Area :. 1.58in X .63in (40mm X 16mm)
  
• Mounting Hole Size : 0.12in (3mm)
  
• Operating Humidity: 10% to 90% (non-condensing)
  
• Working Temperature: (-30 to 50 degrees C)

To connect to the Grove board:

The 3 pins in the module are:

S (Signal) pin is an analog output that will be connected to one of the analog inputs on your Arduino.

+ (VCC) pin supplies power for the sensor. It is recommended that the sensor be powered with 3.3V – 5V. Please note that the analog output will vary depending on what voltage is provided for the sensor.

– (GND) is a ground connection.

First you need to supply power to the sensor. For that you can connect the + (VCC) pin on the module to 5V on the Arduino and – (GND) pin to ground.