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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  • Ligo George says:

    Stainless steel is a poor conductor of electricity.

  • Alexxie says:

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

  • virender says:

    Check new wireless water level indicator

  • Ligo George says:

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

  • tirus wanjau says:

    what type of sensor can we use to vary current

  • Ligo George says:

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

  • Siddharth Naik says:

    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?

  • Ligo George says:

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

  • alejp says:

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

  • Ligo George says:

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

  • Nasar Khan says:

    how can we connect a relay to this circuit

  • Ligo George says:

    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

  • SimpleLife says:

    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.

  • Ligo George says:

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

  • avi123 says:

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

  • Ligo George says:

    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.

  • Alex says:

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

  • Ahmed Abu Sha'ar says:

    what types of wires shoul i use ?

  • Ligo George says:

    reduce the 1K to 680 ohm.

  • Luis Alberto Lucio says:

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

  • maryam hassan says:

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

  • Colin55 says:

    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.

  • Colin55 says:

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

  • abhay bajpai says:

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

  • Smileengineer2010 says:

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

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