In-Depth: How Water Level Sensor Works and Interface it with Arduino

The water level sensor module functions through a series of exposed parallel copper traces that act as a variable resistor. When connected to power and ground via jumper wires, the resistance between the traces changes depending on the depth of the water it submerges into. As water covers more of the sensor surface, conductivity increases, resulting in a proportional rise in analog voltage output. An Arduino Mega 2560 reads this analog voltage through its built-in analog-to-digital converter (ADC). By processing the raw numerical values provided by the ADC, the Arduino can determine the exact fluid level. To provide immediate visual feedback, the system incorporates three LEDs—Red, Yellow, and Green—each protected by a 220-ohm current-limiting resistor. Depending on the threshold limits programmed in the Arduino IDE, the microcontroller triggers different combinations of these LEDs to light up, signifying varying levels from empty to full. This combined analog-reading and digital-output architecture allows undergraduate engineering students to understand how continuous environmental variables can be quantified, thresholded, and mapped onto discrete physical indicators using an Arduino platform.