Basic Electronics for Beginners: Arduino Water Flow Sensor

1. Introduction

Water management is very important in homes, industries, and agriculture. In this project, we design an Arduino-based Water Flow Measurement System using a flow sensor to calculate flow rate (L/min) and total water consumed (liters).

This project is useful for:

Monitoring water usage in homes
Detecting leakage
Smart irrigation systems
Industrial flow measurement

2. Components

Arduino UNO / Nano
Water Flow Sensor (YF-S201)
16x2 LCD Display (optional but recommended)
10K Potentiometer (for LCD contrast)
Connecting wires
Breadboard
Power supply

3. Circuit and Connections

Pinout Diagram of Arduino Uno

Pinout Diagram YF-S201

Pin-out Diagram 16X2 LCD
🔌 Sensor Connections:

Red → 5V
Black → GND
Yellow → Digital Pin 2 (Interrupt Pin)

📺 LCD Connections (Optional):

VSS → GND
VDD → 5V
VO → Potentiometer
RS → Pin 12
EN → Pin 11
D4 → Pin 5
D5 → Pin 4
D6 → Pin 3
D7 → Pin 6

4. Detailed Step By Step Circuit Working

The water flow sensor (YF-S201) contains a rotating turbine inside. When water flows through the sensor:

The turbine rotates
A Hall effect sensor generates pulses
Each pulse represents a small quantity of water
Arduino counts these pulses
Using calibration, flow rate is calculated

👉 More water flow = more pulses

5. Libraries to be included


#include <LiquidCrystal.h>

6. Code


#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 6);

volatile int flow_frequency; 
unsigned int l_hour; 
float total_liters = 0;

unsigned char flowsensor = 2; 

unsigned long currentTime;
unsigned long cloopTime;

void flow () {
   flow_frequency++;
}

void setup() {
   pinMode(flowsensor, INPUT);
   digitalWrite(flowsensor, HIGH);

   lcd.begin(16, 2);
   lcd.print("Water Flow");

   attachInterrupt(digitalPinToInterrupt(flowsensor), flow, RISING);

   currentTime = millis();
   cloopTime = currentTime;
}

void loop () {
   currentTime = millis();
   
   if(currentTime >= (cloopTime + 1000)) {
      cloopTime = currentTime;

      l_hour = (flow_frequency * 60 / 7.5); 
      total_liters += l_hour / 60.0;

      lcd.clear();
      lcd.setCursor(0,0);
      lcd.print("Rate:");
      lcd.print(l_hour);
      lcd.print(" L/hr");

      lcd.setCursor(0,1);
      lcd.print("Total:");
      lcd.print(total_liters);
      lcd.print(" L");

      flow_frequency = 0;
   }
}

7. Detailed Step By Step Code Working

flow_frequency → counts pulses from sensor
Interrupt function flow() → increments pulse count
Every 1 second:
- Flow rate calculated using formula
- Display updated on LCD

👉 Formula used:

Sensor gives ~7.5 pulses per liter/min
Converted into liters/hour

8. Working Principle

The project works based on the Hall Effect Principle.

Water rotates turbine
Magnet passes Hall sensor
Pulse generated
Arduino counts pulses
Converts into flow rate

9. Advantages

Simple and low cost
Accurate measurement
Real-time monitoring
Easy to expand (IoT, logging)

10. Disadvantages

Requires calibration for high accuracy
Affected by impurities in water
Not suitable for very high pressure

11. Applications

Smart water meters
Industrial liquid measurement
Agriculture irrigation systems
Water usage monitoring in homes

12. Conclusion

This project demonstrates how to measure water flow using an Arduino and a simple sensor. It is a highly practical system that can be extended to IoT-based monitoring and automation.

Arduino Water Flow Sensor