This water sensor is designed for water detection and can be widely used in sensing rainfall level, overflow level or even liquid leakages. The sensor is mainly comprised of three parts: An electronic connector, a 1 M resistor and several lines of bare conducting wires.
This sensor works by having a series of exposed traces connected to ground and interlaced between these are the sense tracers. The sensor tracers have a weak pull-up resistor of 1 M. The resistor will pull the sensor trace value high until a drop of water shorts the sensor to the grounded trace. This module will work with the digital I/O pins of your Arduino or you can use it with the analogue pins to detect the amount of water between the grounded and sensor tracers.
This item judges the water level through a series of exposed parallel wires, which measure the amount of water present.
This item uses very little power and is highly sensitive, which are excellent characteristics of this type of module.