Water Level Indicator

If you are tired of continuously monitoring the water level of the overhead tank of your house, then you can relax now by creating your own water level indicator.

This indicator beeps whenever the water is in contact with the probe. This beeps continuously till you turn off the water pump.


  • 330k ohm resistor
  • 10k ohm resistor
  • 10microFarad capacitor
  • BC548
  • BC558
  • 8ohm speaker
  • Probe
  • 3v battery
  • Connecting wires
  • PCB (Printed Circuit Board)
  • Multimeter


How to make it:

Once you have gathered all the components, cross check the components as per the requirements.

Now connect the components as shown in the circuit diagram. Once you rig up the circuit make sure the short circuit test and the continuity test is done with the help of the multimeter.

Now power up the circuit and place it on the surface of the overhead tank. Once the probe gets contact with water, there will be flow of current. This current will turn ON the BC548 transistor. BC548 is an NPN bipolar junction transistor. This in turn powers up the BC558 transistor, which causes the current to flow through the speaker. BC558 is a PNP transistor.

Inductive coil in speaker causes the flow of current in one direction. The induced current in the speaker flows in the opposite direction of the flow of current. This flows in the form of pulse through the capacitor and resistor, switching off the BC548 transistor. This process repeats till the probe is in contact with water, making the speaker diaphragm vibrate. Sound will be produced whenever the speaker diaphragm vibrates.

The output of the speaker depends upon the speaker watts and impedance values.


About Pavan Shetty

Masters in Embedded systems, Intern Embedded Engineer.

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