Water Level Indicator Using Arduino

Water level monitoring is a simple yet essential task in many household and industrial applications. Whether it's preventing the overflow of a water tank or automating an irrigation system, monitoring the water level can help avoid wastage and ensure proper use of water resources. In this project, we will build a water level detection system using an Arduino, a water level sensor, and a few basic components. This system will provide both visual (LED) and audio (buzzer) alerts when the water reaches a specified level.

Supplies

Water Level Sensor

The water level sensor operates based on the change in resistance as water touches different parts of its conductive path. The sensor consists of 10 exposed traces out of which 5 are power traces and 5 are sensor traces.

When the water reaches different heights on the sensor, the water bridges the traces, altering the sensor's resistance. The sensor outputs an analog signal that corresponds to the water level, which is then fed into the Arduino for processing. This analog value changes with the level of immersion of the sensor in the water, allowing us to detect the height of the water.

Water Level Sensor Pinout

The water level sensor module typically has three pins:

VCC: Power input (3.3V–5V, connect to Arduino 5V).
GND: Ground (connect to Arduino GND).
SIG: Signal output pin (connect to Arduino analog input, usually A0).

Wiring Connections

This simple setup allows the Arduino to read the water level from the sensor and trigger the RGB LED and buzzer when the water level crosses the threshold.

The Arduino controls the RGB LED to display different colors for different water levels. When the water level is below 10%, the RGB LED will glow red. If the water level is between 10% and 99%, the LED will emit a blue light. Once the water level reaches 99% or more, the LED turns green, and the buzzer activates, signaling that the container is full and should no longer be filled.

Wiring Connections

First we connect the VCC pin of the water level sensor to the 5V pin of the Arduino. Then we connect the GND pin of the sensor to the GND pin on the Arduino. Then connect the SIG pin of the sensor to the Arduino's A0 pin (Analog input).

Now we connect a common cathode LED connected with the Arduino at pins 10, 9 and 8 for colours red, blue and green respectively. A buzzer is connected at pin 2.

Arduino Code

#include <LiquidCrystal_I2C.h> // Library to Run I2C LCD

// define the size of filter array

#define FILTER_SIZE 20

#define LOWER_THRESHOLD 4

#define UPPER_THRESHOLD 650

#define RED_PIN 10

#define BLUE_PIN 9

#define GREEN_PIN 8

#define BUZZER_PIN 2

// Set the LCD address to 0x27 for a 16 chars and 2 line display

LiquidCrystal_I2C lcd(0x27, 16, 2);

// Define the Analog pin for the soil moisture sensor

const int WaterSensorPin = A0;

// Analog Value filter

int Filter(int sensorValue);

void setup() {

// initialize the lcd

lcd.init();

// Turn on the Backlight

lcd.backlight();

// Clear the display buffer

lcd.clear();

// Make LED pins and Buzzer pin as output

pinMode(RED_PIN, OUTPUT);

pinMode(BLUE_PIN, OUTPUT);

pinMode(GREEN_PIN, OUTPUT);

pinMode(BUZZER_PIN, OUTPUT);

// Turn Off all the pins

digitalWrite(RED_PIN, LOW);

digitalWrite(BLUE_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

digitalWrite(BUZZER_PIN, LOW);

// Print a message to the LCD

lcd.setCursor(0, 0);

lcd.print("Fill Percent:");

}

void loop() {

// Variable to store sensor values

int sensorValue;

// Variable to store filtered Value

int filteredValue;

// Variable to store fill percentage

int fillPercent;

// Read the value from the soil moisture sensor

sensorValue = analogRead(WaterSensorPin);

filteredValue = Filter(sensorValue);

fillPercent = map(filteredValue,LOWER_THRESHOLD, UPPER_THRESHOLD, 0, 100);

// Display the filtered Analog Value on the LCD

lcd.setCursor(0, 1);

lcd.print(fillPercent);

// Clear Previous Data

lcd.print("% ");

// Change the color of LED as per water level

if (fillPercent >= 99) {

digitalWrite(RED_PIN, LOW);

digitalWrite(BLUE_PIN, LOW);

digitalWrite(GREEN_PIN, HIGH);

digitalWrite(BUZZER_PIN, HIGH);

} else if (fillPercent >= 10 && fillPercent < 99) {

digitalWrite(RED_PIN, LOW);

digitalWrite(BLUE_PIN, HIGH);

digitalWrite(GREEN_PIN, LOW);

digitalWrite(BUZZER_PIN, LOW);

} else if (fillPercent < 10) {

digitalWrite(RED_PIN, HIGH);

digitalWrite(BLUE_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

digitalWrite(BUZZER_PIN, LOW);

}

// Wait for 50ms before the next loop

delay(50);

}

// Averaging filter to filter Analog Values

int Filter(int sensorValue) {

static int analogArray[FILTER_SIZE] = { 0 };

int filteredValue = 0;

int i;

// Shift the Element removing the oldest value stored at index 0

for (i = 0; i < (FILTER_SIZE - 1); i++) {

analogArray[i] = analogArray[i + 1];

}

// Put the current value in the last element of Array i.e. at index FILTER_SIZE-1

analogArray[FILTER_SIZE-1] = sensorValue;

for (i = 0; i < FILTER_SIZE; i++) {

filteredValue += analogArray[i];

}

// Return Filtered Analog Value

return (filteredValue / FILTER_SIZE);

}

Working

Once the circuit is set up and the Arduino code is uploaded, the project works by continuously monitoring the analog signal from the water level sensor. The sensor detects the current water level and sends an analog signal to the Arduino, which reads it through pin A0. The Arduino then compares the sensor reading to a predefined threshold. If the water level exceeds this threshold, the Arduino triggers both the buzzer and the LED to notify that the water has reached a critical level.

To learn how to build a water level indicator checkout: Water Level Sensor with Arduino