Interfacing Plastic Liquid Level Float Switch with Arduino

Table of Contents

Liquid Level Float Switch Features

The liquid level float switch is a very simple sensor that works like a switch. This sensor places vertically, floating on water. The float is located on a pipe that can move on the liquid surface. It works based on the magnetic field.


Until you have not placed the sensor on the liquid surface, the switch is closed and when the sensor is placed on the liquid, the float moves on the pipe and goes up and the switch remains open.

Liquid Level Float Switch Pinout

The liquid level float switch has two wires that two switch ends are inside it. When it is on the surface of the water it is open and otherwise it is closed.

Required Materials

Hardware Components

Arduino UNO R3 × 1
Liquid Level Float Switch × 1
Liquid Level Float Switch × 1

Software Apps

Arduino IDE

Interfacing Liquid Level Float Switch with Arduino

Step 1: Circuit

The following circuit shows how you should connect Arduino to the float switch. Connect wires accordingly.


We use the Arduino internal resistor to pull-up the switch.

Step 2: Code

Upload the following code to Arduino.

  Liquid Level Float Switch
  made on 13 oct 2020
  by Amir Mohammad Shojaee @ Electropeak
*/ void setup() { pinMode(2,INPUT_PULLUP); Serial.begin(9600); } void loop() { if(digitalRead(2)== HIGH){ Serial.println("On Water"); while(digitalRead(2)== HIGH) {} delay(100); } else{ Serial.println("Outside Water"); while(digitalRead(2)== LOW) {} delay(100); } }

We first set Pin 2 as Input Pull-Up. The phrase “On Water” is displayed when the float is on water (i.e. the switch is open and connected to the Vcc) and the phrase “Outside Water” is displayed when it is not on the water.

The output is as follows.

As you see, the switch state changes by putting sensor inside or outside water.

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