💧 Water Quality Monitoring System

(ESP32 + Analog TDS Sensor + Blynk IoT Cloud)

In this lesson, we upgrade the system to Cloud-Based Monitoring using Blynk IoT.

This version allows:

• 🌍 Monitor water quality from anywhere

• 📊 Real-time TDS (PPM) display

• 💧 Water quality classification on dashboard

• 🚨 Alert if water is unsafe

• ☁ Cloud-based data monitoring

Internet required ✔
WiFi required ✔
Blynk IoT Cloud ✔

📦 Components Used

• ESP32

• Analog TDS Sensor Module

• TDS Probe

• WiFi Connection

• Blynk IoT Account

🔌 Pin Configuration

GPIO 34 = Analog Input

🌐 Blynk IoT Setup (Step-by-Step)

Go to:
👉 https://blynk.cloud

Login and follow the steps below.

🔹 Step 1 – Create Template

1. Click New Template

2. Template Name:

    

   Water Quality Monitor

    

3. Hardware: ESP32

4. Connection Type: WiFi

5. Click Done

🔹 Step 2 – Create Datastreams

Go to Datastreams → New Datastream

1️⃣ V0 – TDS Value (PPM)

• Type: Virtual Pin

• Pin: V0

• Data Type: Double

• Min: 0

• Max: 2000

Used to display TDS value.

2️⃣ V1 – Water Quality Text

• Type: Virtual Pin

• Pin: V1

• Data Type: String

Used to display water quality status.

3️⃣ V2 – Unsafe Water LED

• Type: Virtual Pin

• Pin: V2

• Data Type: Integer

• Min: 0

• Max: 1

1 = Unsafe
0 = Safe

🔹 Step 3 – Create Device

1. Go to Devices

2. Click New Device

3. From Template

4. Select Water Quality Monitor

5. Copy Auth Token

You will paste it into code.

📱 Dashboard Setup (Mobile App)

Open Blynk App and add:

📊 Value Display – TDS Value

Datastream: V0

📝 Label / Value Display – Water Quality

Datastream: V1

💡 LED Widget – Unsafe Water

Datastream: V2
ON Color: Red
OFF Color: Green

💻 COMPLETE CODE

(ESP32 + TDS Sensor + Blynk IoT)

Replace credentials before uploading.

#define BLYNK_TEMPLATE_ID "YOUR_TEMPLATE_ID"
#define BLYNK_DEVICE_NAME "Water Quality Monitor"
#define BLYNK_AUTH_TOKEN "YOUR_AUTH_TOKEN"

#include <WiFi.h>
#include <BlynkSimpleEsp32.h>

#define TDS_PIN 34

char ssid[] = "YOUR_WIFI_NAME";
char pass[] = "YOUR_WIFI_PASSWORD";

float voltage = 0;
float tdsValue = 0;
String waterQuality;

void setup() {
Serial.begin(115200);

Blynk.begin(BLYNK_AUTH_TOKEN, ssid, pass);
}

void loop() {
Blynk.run();

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;

// Water Quality Classification
if (tdsValue < 50) {
waterQuality = "Very Pure";
Blynk.virtualWrite(V2, 0);
}
else if (tdsValue < 150) {
waterQuality = "Excellent";
Blynk.virtualWrite(V2, 0);
}
else if (tdsValue < 300) {
waterQuality = "Good";
Blynk.virtualWrite(V2, 0);
}
else if (tdsValue < 500) {
waterQuality = "Fair";
Blynk.virtualWrite(V2, 0);
}
else {
waterQuality = "Poor / Unsafe";
Blynk.virtualWrite(V2, 1);
}

Blynk.virtualWrite(V0, tdsValue);
Blynk.virtualWrite(V1, waterQuality);

delay(2000);
}

🧠 Code Explanation

1️⃣ Blynk Initialization

Connects ESP32 to:

• WiFi

• Blynk Cloud

• Your dashboard

2️⃣ Read Analog Value

Reads TDS sensor voltage.

Range:
0 – 4095

3️⃣ Convert ADC to Voltage

Converts ADC value into voltage.

4️⃣ Convert Voltage to TDS

Polynomial equation converts voltage to PPM.

5️⃣ Water Quality Classification

Based on TDS value:

If water is unsafe:

Turns ON red LED.

6️⃣ Dashboard Updates

Updates:

• TDS numeric display

• Water quality text

📟 System Working Flow

1. ESP32 connects to WiFi

2. Connects to Blynk Cloud

3. Reads TDS sensor

4. Converts voltage to PPM

5. Classifies water quality

6. Updates dashboard

7. Turns LED ON if unsafe

🎯 What Students Learn

• Cloud-based IoT system

• Virtual pins concept

• ADC & voltage conversion

• Polynomial calibration formula

• Environmental IoT monitoring

• Real-time cloud dashboard

📌 Lesson Summary

In this lesson, students built a:

💧 Cloud-Based Water Quality Monitoring System

The system:

✔ Measures TDS
✔ Classifies water quality
✔ Sends data to cloud
✔ Alerts if water is unsafe
✔ Monitors from anywhere