Arduino Ultrasonic Automatic Water Level Controller

📖 1. Introduction

Monitoring water level manually is difficult and often leads to overflow or dry running of motors. A smart system with display gives real-time information.

In this project, we design a reliable water level controller with LCD display using:

👉 JSN-SR04T Waterproof Ultrasonic Sensor
👉 16x2 LCD for real-time level display
👉 Automatic motor control using relay

This system is accurate, durable, and user-friendly.

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🔧 2. Components

• Arduino UNO
• JSN-SR04T Waterproof Ultrasonic Sensor
• 16x2 LCD Display with I2C Module
• Relay Module (5V)
• Water Pump / Motor
• Buzzer (optional)
• Connecting wires
• 5V Power Supply

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🔌 3. Circuit and Connections

📍 Ultrasonic Sensor:

• VCC → 5V
• GND → GND
• TRIG → Pin 6
• ECHO → Pin 7

📍 Relay:

• INPUT → Pin 8
• Motor One end to Phase other to Normally Open pin 
• Common Contact  → Neutral Point

📍 Buzzer:

• • Positive → Pin 9
  • Negative → GND

📍 LCD (I2C):

• VCC → 5V
• GND → GND
• SDA → A4
• SCL → A5

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⚙️ 4. Step by Step Circuit Working

1. Ultrasonic sensor measures distance from tank top to water
2. Arduino calculates water level
3. Converts it into percentage (%)
4. Displays:
   • Water Level (cm)
   • Percentage (%)

Decision Logic:

• Low level → Motor ON
• Full tank → Motor OFF
• LCD shows live status

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💻 5. Code

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define trigPin 6
#define echoPin 7
#define relay 8
#define buzzer 9

LiquidCrystal_I2C lcd(0x27, 16, 2);

long duration;
int distance;
int waterLevel;

int tankHeight = 40; // cm

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(relay, OUTPUT);
  pinMode(buzzer, OUTPUT);

  lcd.init();
  lcd.backlight();

  Serial.begin(9600);
}

int getDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  return duration * 0.034 / 2;
}

void loop() {

  long total = 0;

  for(int i = 0; i < 5; i++) {
    total += getDistance();
    delay(50);
  }

  distance = total / 5;
  waterLevel = tankHeight - distance;

  int percentage = (waterLevel * 100) / tankHeight;

  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Level:");
  lcd.print(waterLevel);
  lcd.print("cm");

  lcd.setCursor(0,1);
  lcd.print("Fill:");
  lcd.print(percentage);
  lcd.print("%");

  if (waterLevel < 10) {
    digitalWrite(relay, HIGH);
    digitalWrite(buzzer, LOW);
  }

  else if (waterLevel > 35) {
    digitalWrite(relay, LOW);
    digitalWrite(buzzer, HIGH);
  }

  delay(1000);
}

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🔍 6. Step by Step Code Working

• LiquidCrystal_I2C → controls LCD
• getDistance() → reads ultrasonic data
• 5 readings averaged → improves accuracy
• Water level calculated
• Converted to percentage (%)

LCD Output:

• Line 1 → Level in cm
• Line 2 → Percentage

Control:

• Low → Motor ON
• Full → Motor OFF

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💡 7. Tips

✔ Use correct I2C address (0x27 or 0x3F)
✔ Mount sensor vertically
✔ Use enclosure for protection
✔ Adjust tank height correctly
✔ Use good quality power supply

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🚀 8. Uses

• Smart home water tank
• Apartment automation
• Industrial monitoring
• Farming irrigation systems

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⚠️ 9. Common Issues and Solutions

❌ LCD not displaying

✔ Check I2C address

❌ Wrong readings

✔ Adjust tank height
✔ Use averaging

❌ Flickering display

✔ Add delay

❌ Sensor error

✔ Check wiring and alignment

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🧠 10. Conclusion

This project combines automation + monitoring + display, making it a complete smart water management system.

It is highly suitable for real-world implementation and student learning.