Simple Water Level Indicator with Alarm (Tested Circuits)

Generally, water stored in overhead tank is wasted due to over flow ,when the tank is full. Water level alarm using micro-controllers like 8051 and AVR are shown in previous articles.This article shows simple circuits of water level indicator with alarm.

Three circuits were shown  here  are simple and built using transistors, 555 timer and  ULN2003 IC. First let us build a water level alarm using simple transistors.

Water Level Indicator Using Simple Transistors

Circuit Diagram

Water Level Control using Transistor Circuit

Components Required

  • BC548 transistors-Q1,Q2,Q3,Q4
  • Resistors R1,R2,R3,R4-2.2kohms
  • R5, R6 ,R7 – 100 ohm
  • Led – Red(LED3) , Green(LED1) , Yellow(LED2)
  • Metal Contacts – M1,M2,M3,M4.

Working

  • The circuit is designed to indicate three levels of water stored in the tank: low but not empty, half and full but not overflowing.
  • When there is no water in the tank, all the LEDs are off as an indication that the tank is completely empty.
  • When water level increases and reaches M2, the contacts M1 and M2 get shorted as water acts as a conducting medium between M1 and M2.
  • This will turn on the transistor Q1 and the Green LED starts to glow. As the water level continues to rise and reaches half the tank, M3 will come into contact with water and receives a small voltage from M1.
  • As a result, Q2 is turned on and Yellow LED will glow. When the water in the tank rises to full tank, M4 is also shorted with M1 and both Q3 and Q4 will turn on.
  • The Red LED glows and also an alarm is made by the buzzer as an indication that the tank is full and the water pump or motor can be turned off.  

Note:This circuit does not show a buzzer.Connect a Buzzer,resistor and transistor  in series and connect this in  parallel to the last LED.

Water Level Alarm Using 555 Timer 

Here is the circuit using 555 timer IC.

Circuit Diagram

Water Level Indicator using NE555 Circuit

Components Required

  • NE555 Timer
  • Resistors 
    • R1,R4-1K
    • R2-22k
    • R3-570 Ohm
  • Capacitor- 1UF
  • Buzzer
  • Connecting wires

Working

The circuit uses a 555 timer in astable mode with R1=22k ohms, R2= 570 ohms and C1=1 uF. The frequency of the given astable circuit is around 62 Hz.

The two probes which are shown in the circuit should be kept at the high level for the water. The distance between the probes should be less than a few centimetres to ensure that the conduction between the probes will take place when water is touched to these probes.

When the water level rises to the height of the probes, then the 555 circuit will get enabled and the output of the 555 timer produces a square wave output with a frequency of about 62 Hz. This output is given to the buzzer.

The logic Implemented in this circuit is, 555 timer is enabled when its reset pin is connected to logic high. But initially it is connected to ground. When the water level is maximum this pin is enabled and this drives the 555 timer into astable mode. 

Water Level Indicator and Alarm Using ULN2003

One can implement this circuit using simple ULN2003 IC.IC ULN2003 consists of an array of seven Darlington transistor pairs.

Circuit Diagram

Water Level Indicator using ULN2003 Circuit

Components Required

  • L1-L3-LEDs
  • R1-R3-1k ohm
  • M1-M7-Metal Contacts
  • ULN2003 IC

Working

  • This circuit can be used to indicate three levels of water in tanks.
  • When metal contact is reached ,each Led starts glowing.
  • When the tank is full buzzer starts ringing along with this all LEDs are ON.

Also Read the Post: Water Level Indicator Using AVR Microcontroller

80 Responses

  1. i need water level contact no or nc
    2 no tank 1st is botam and second is up
    wean bottom tank water level hi this time
    give “nc” contact to motor wean upar tank
    full this time all system are stop.
    pleas i received circuit dayogrm
    1st refrains ic 555
    thank you..

    1. Please check the circuit diagram for components..All the components with their ratings are provided in the circuit diagram itself

    1. Here we used 8 ohms speaker…Please check the circuit diagram to know how to connect speaker… Where and why do you want to connect the switch??

  2. how can i implement the water level alarm in a tank which is placed in the vehicle and also i want to cut the supply automatically when tank is filled

  3. please explain the the principle behind it.so,that we can something cool with it……!!!!
    thamk you sir…..!!!!

  4. HOW THE CONTACT TYPE CAPACITIVE WATER LEVEL SENSOR CAN BE CONNECTED TO ARDUINO BOARD UNO BOARD? I USED SS CONTACT TYPE SENSOR.

  5. partianing the circuit where you used transistors for the water indicator circuit, how can i make the red LED turn off while the amber led stays on, cause i Want the amber to indicate stable mode, so when its in stable mode the red LED turns off but when it goes below the stable mode, the red LED turns on, what can i do pls. thanks

  6. Excuse me please can i know the name of the publisher of this article, want to include it in my proposal, thank you

  7. Water Level Detector Using Simple Transistor.
    why should we use transistors if we can directly connect led with Current Limiting Resistor?

  8. My requirement is that after every 15 minute the motor should run for 2 minutes then halt then again start after 15 minute.
    Please provide me the details for this circuit…

  9. If the circuit is places near the tank how can we see that LEDs are glowing or not and we are unable to hear sound of a buzzer.can u please explain me

    1. PLEASE GUYS HELP ME .ITS OK IT PLACED ON THAT .IT IS NOT AN ISSUE. BUT IN 555 TIMER WE KNOW WHEN WATER REACHES THE PEAK THE BUZZER WILL ON.BUT HOW TO KNOW THE TANK S EMPTY. WHEN OUR ISMOTOR IS ON IN ORDER TO FILL THE TANK. 1STLY WE KNOW RIGHT.HOW MUCH WATER PRESENT IN WATER LEVEL.

  10. THANK U FOR UPLOADING GOOD PROJECT LIKE THIS. I GET A SMALL DOUGHT ABOUT USING 555 TIMER CIRCUIT . IN THAT THE BUZZER WILL RING WHEN WATER LEVEL REACHED TO PEAK LEVEL .BUT HOW TO KNOW THE TANK IS EMPTY. FOR KNOWING THAT WE HAVE TO KEEP ONE
    THRESHOLD LEVEL .HOW IT POSSIBLE IN THIS CIRCUIT.PLEASE GIVE RESPONCE QUICKLY.

    1. Here we used only IC’s and Transistors as a major components. So, no need for any programming.

  11. I have assembled the first circuit and powered with 12 Volt supply; On switching on the circuit all the led are dimmly lit. Why it is so happening. Kindly enlighten me and give me the rectification for this.

    1. first of all, have you modified the circuit to work with 12V??
      if yes, then try to connect 10kΩ resistors to all the base of the transistors to ground.

  12. Water Level Indicator Using Simple Transistors

    Connect a Buzzer, resistor and transistor in series and connect this in parallel to the last LED.

    Could you please add this to the diagram, I need to see it, to understand

    Thank you

  13. I want to use ULN2003 as water indicator circuit. I want to combine my existing water lever controller with new indicator circuit. my current controller circuit uses 0v as input from tank not the vcc to avoid scale formation on the contacts. This means 0v wire is given to tank water and signal from different level is received to glow the LED and trigger the motor SSR. how to use ULN2003AN to receive 0V as input on base as signal from tank and glow the LED at different water level?

    1. if you already implemented this kind of project I suggest you to upgrade this project using magnetic relays instead of using electrodes.

  14. Your connection video is not clear. not clear means dont know where the wire connected.so can you please upload a new video or clear detail about connection.

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