💧 Water Quality Monitoring System

(ESP32 + Analog TDS Sensor + Bluetooth)

In this lesson, we upgrade the Serial Monitor version to Bluetooth control and monitoring.

This version allows:

• 📱 Real-time TDS value on mobile

• 📊 Water quality classification

• 🔄 Wireless communication

• 📡 No WiFi required

Internet ❌
Router ❌
Bluetooth ✔

📦 Components Used

• ESP32

• Analog TDS Sensor Module

• TDS Probe

• Android Phone

• Serial Bluetooth Terminal App

Recommended App:
👉 Serial Bluetooth Terminal (Android)

🔌 Pin Configuration

GPIO 34 = Analog Input Pin

💻 COMPLETE CODE

(Bluetooth + TDS Monitoring)

Copy & paste into Arduino IDE:

#include <BluetoothSerial.h>

BluetoothSerial SerialBT;

#define TDS_PIN 34

float voltage = 0;
float tdsValue = 0;

void setup() {
Serial.begin(115200);
SerialBT.begin("Water_Quality_BT");

SerialBT.println("=== Water Quality Monitoring ===");
}

void loop() {

int adcValue = analogRead(TDS_PIN);

voltage = adcValue * (3.3 / 4095.0);

tdsValue = (133.42 * voltage * voltage * voltage 
- 255.86 * voltage * voltage 
+ 857.39 * voltage) * 0.5;

SerialBT.print("TDS Value: ");
SerialBT.print(tdsValue);
SerialBT.print(" ppm");

// Water Quality Classification
if (tdsValue < 50) {
SerialBT.println(" | Very Pure Water");
}
else if (tdsValue < 150) {
SerialBT.println(" | Excellent Water");
}
else if (tdsValue < 300) {
SerialBT.println(" | Good Water");
}
else if (tdsValue < 500) {
SerialBT.println(" | Fair Water");
}
else {
SerialBT.println(" | Poor / Unsafe Water");
}

delay(2000);
}

🧠 Code Explanation

1️⃣ Enable Bluetooth

Creates Bluetooth device named:

Your phone will detect this name.

2️⃣ Read Analog Value

Reads analog signal from TDS module.

Range:
0 – 4095

3️⃣ Convert ADC to Voltage

Converts ADC value to voltage.

4️⃣ Convert Voltage to TDS

Polynomial formula converts voltage to PPM.

5️⃣ Water Quality Classification

Based on TDS value:

The app shows both TDS value and quality.

📱 How To Use Bluetooth App

Step 1
Upload code

Step 2
Turn ON Bluetooth

Step 3
Open Serial Bluetooth Terminal

Step 4
Connect to:

Step 5
View live TDS value on screen

📟 Example Output in Mobile App

🎯 What Students Learn

• Bluetooth communication

• Analog sensor reading

• Voltage to PPM conversion

• Water quality classification

• Wireless environmental monitoring

📌 Lesson Summary

In this lesson, students built a:

💧 Bluetooth-Based Water Quality Monitoring System

The system:

✔ Reads TDS sensor
✔ Converts voltage to PPM
✔ Classifies water quality
✔ Sends data wirelessly to mobile