Simple Water Level Indicator

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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Comments (26)

  • Smileengineer2010

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

    November 18, 2012 at 5:17 am
  • abhay bajpai

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

    December 16, 2012 at 12:36 pm
  • Colin55

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

    March 7, 2013 at 5:18 am
  • 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.

    March 7, 2013 at 9:21 am
  • maryam hassan

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

    March 26, 2013 at 9:22 pm
  • Luis Alberto Lucio

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

    October 11, 2013 at 12:20 am
  • Ligo George

    reduce the 1K to 680 ohm.

    October 14, 2013 at 7:20 am
  • Ahmed Abu Sha'ar

    what types of wires shoul i use ?

    February 26, 2014 at 6:31 pm
  • Alex

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

    August 8, 2014 at 10:57 am
  • 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.

    August 9, 2014 at 8:57 pm
  • avi123

    Sir, Is the negative of the 9V source connected to the lower part of the water tank. Im not understanding. Plz reply.

    October 30, 2014 at 10:23 pm
  • Ligo George

    No, Positive of the 9V battery is connected to the water..

    October 31, 2014 at 5:17 pm
  • SimpleLife

    What about corrosion. Here in Mira Bhayandar we quite frequently use Creek Water or Well/”Boring” water along with Tap (Sweet) water. If we use copper wire there may be corrosion. Is there a solution for this problem.

    March 24, 2015 at 11:18 pm
  • Ligo George

    Yes, there will be corrosion..
    1. AC voltage sensing avoids corrosion.
    2. You may use Float or Tilt sensor to avoid corrosion
    3. Reduce sensing current to reduce corrosion

    March 29, 2015 at 11:15 am
  • Nasar Khan

    how can we connect a relay to this circuit

    July 12, 2015 at 3:24 pm
  • Ligo George

    It is a simple water level indicator. You need additional components to add relay.

    July 18, 2015 at 11:20 am
  • alejp

    Is possible no to use the 47k resistor on the base?. What would happen?

    October 10, 2015 at 8:10 pm
  • Ligo George

    You can reduce or increase the value of base resistor depending upon the required sensitivity.

    November 21, 2015 at 1:15 pm
  • Siddharth Naik

    I read that ionization leads to deposits on the terminals inserted in water. This means you have to clean the terminals frequently. How to avoid this?

    December 8, 2015 at 10:30 am
  • Ligo George

    You can use the following.
    1. AC Sensing
    2. Reduce current
    3. Use float sensors

    December 19, 2015 at 3:49 pm
  • tirus wanjau

    what type of sensor can we use to vary current

    January 28, 2016 at 3:43 pm
  • Ligo George

    Sorry, I don’t understand your question. Please elaborate.

    January 30, 2016 at 4:32 pm
  • virender

    Check new wireless water level indicator

    April 14, 2016 at 8:57 pm
  • Alexxie

    use stainless steel screws as terminals ,wont gets corroded ever.

    April 19, 2016 at 1:43 pm
  • Ligo George

    Stainless steel is a poor conductor of electricity.

    June 2, 2016 at 6:08 pm

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