Water Level Indicator Circuit Using Transistor

We generally worry about the wastage of water, when we switch ON the motor and forget to turn it off. The Water Level Indicator employs a simple mechanism to detect and indicate the water level in an overhead tank or any other water container.We have posted already a Water Level Indicator and Controller using IC ULN2003. In this article we are presenting a very useful, cheap and a simple circuit using transistors (bc547) for beginners. This circuit indicates the level of water in water tank using LEDs with transistors. you can use this project as college project.

Circuit Components

Circuit Diagram

water level indicator using transistor

The connections arrangements shown in the circuit diagram shown aove. The +9V power supply or battery is used. In this circuit we have used all the transistors as a switch. The water touches the wires contact with base of each transistor, a small current flows through the base and turns on the transistor as transistor turns on, LED connected to it glows. LEDs will be turned on depending up on the level of water. We have used a buzzer with last transistor as water touch the base of last transistor collector the collector and emitter connected and buzzer rings. Relay can be connected instead of buzzer to auto control the water level in the tank.

Points of BC 547

BC547 transistor points

Resistor 220 Ohm

220ohm resistor

Applications & Uses Of Water Level Indicator

  • Water tank level control
  • Automatically turn ON/OFF water pumps
  • It is used in factories, commercial complexes, apartments, home,
  • Fuel tank level indicator
  • Oil tank level control and indicator
  • High & low level alarms
  • Pool water level control
  • Leach-ate level control
  • Cooling tower water level control
  • Sewage pump level control
  • Remote monitoring liquid
  • Pump controller Auto
  • Stream level monitoring auto

Water Level indicator with auto cut off circuit

In this circuit we have used a relay instead of buzzer as tank will become full relay will be change its state and will cut off the power. We are going to control water pup with this relay, So you must use a power full relay because low power relay will be damaged as more impairs will cross through it.

Water-Level-Indicator-cut off circuit

for more detail and for any question you can ask any question through comments section.

Watch video for practical 



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Add a Comment
  1. Hi, I want to use 7 led for each different levels. My 1000L tank height is about 50ft from ground level. So I’m have to use 50ft ethernet cable for this. I’ll use my router adapter to connect wall plug. Which circuit do you recommend? This one or other one with ULN2003? ULN2003 Seems easy to me. So I like ULN2003. What do you think?

    Here is my router adapter,
    Input: 100-220V~ 50/60Hz 0.3A
    Output: 9V 0.6A

    Your website is really helpful. I’ll use your tutorials for my home DIY projects. Thanks for sharing your knowledge with us.

    1. you can use 7 led if you use transistor then you will have to use 7 transistors
      but ic will be best visit this post if you want ic

  2. If I use battery of 3.0 v instead of 9v. what will be the value of Resistor need? Is it work too.

    1. then dont use any resistor connect leds directly with transistor collector point
      sorry for late answer

  3. Use this Relay 220 v or Dc24v. Pls aks me

    1. use 12v relay to operate 220v AC

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