Simple Water Level Indicator

We have already posted about a Water Level Indicator and Controller using PIC Microcontroller. Today I am presenting a very useful, very cheap and very simple circuit using transistors for beginners in the field of electronics. This simple circuit can indicate the level of water in your tank using LEDs.

Circuit Diagram

Simple Water Level Indicator Circuit Diagram

Simple Water Level Indicator Circuit Diagram

The connections and arrangements are made as shown in the figure above. The +9V is supplied to water using a metal contact.  In this circuit all the transistors are working as a switch. When the water touches the metal contact in which base of each transistor is connected, a small current flows and turns on the transistor. When a transistor turns on, LED connected to it glows.  Thus LEDs will be turned on depending up on the level of water. By using a relay we can also control the level of water.


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  • Smileengineer2010

    when the tank is full three led are on and the battery will empty

  • abhay bajpai

    led takes very low power from the source…a single battary can work minimum one month

  • Colin55

    You should have a current-limiting resistor in series with each LED

  • Colin55

    The circuit will not work with 4.7k resistors in the collectors. The correct way to write values is 4k7 so the decimal point is not needed. The correct value is 470R.

  • maryam hassan

    can u please help me if i want to implement motor to fill my tank if the taank comes to empty portion…

  • Ligo George
  • Luis Alberto Lucio

    hi if i use a 5 volt power supply what changes i need to make?

  • Ligo George

    reduce the 1K to 680 ohm.

  • Ahmed Abu Sha’ar

    what types of wires shoul i use ?

  • Alex

    is there a way to shut off the empty light when the water is in full level ? pls help me sir . thanks :)

  • Ligo George

    You should use more components for that.. it will loss the simplicity of above circuit.

    Take that leds as for indicating water level. instead of assign an led as EMPTY.