DIY Water Level Indicator using BC547 NPN Transistor

Let’s get started with a very useful project which is a Water Level Indicator. Nowadays, almost everyone has an overhead tank in their home. However, anyone who owns a water tank above ground is familiar with the issues that they face like water tank overflow as well as tank exhausting without any previous clue. Most of the time water starts spilling out of the tank which shows wastage of water and energy. 

Components Required

Introduction to BC547 NPN Transistor

Introduction to BC547 NPN Transistor, BC547 pins, BC547 symbol

BC547 is a Bipolar Junction NPN Transistor. It is primarily used for switching as well as amplification. BC547, like the other transistors, is used for current amplification. The smaller current at the base is used to control the larger currents at the collector and emitter.

Characteristics of BC547 NPN Transistor

  • DC Current Gain (hFE) is about 110-800
  • Continuous Collector Current (IC) is 100mA
  • Emitter Base Voltage (Vbe) is 6 Volts
  • Collector Emitter Voltage (Vce) is 30V
  • Collector Base Voltage (Vcb) is 30V
Wires  are submerged in the tank at different levels with one common VCC wire and the input simply goes to a transistor to turn on an LED, A buzzer can also be used at bottom or top level. Selection of probe material is important as the very low current flowing through them in liquid medium, submerged sensor wires are prone to corrosion and calcification by the minerals present in water. As a result, they cease to function properly after a few months or a year. So, you can use graphite probes for your sensor.


Circuit Diagram

circuit diagram for Water level indicator
Diy projects




Dear sir,
I am doing this project without using transistors and other electronics for getting a signal for particular level I am going to hang se about five water level sensor which is based on relays it is having two contacts when water level is achieved then it becomes make contact and when water level goes below the sensor it becomes a break contact so this is the easiest possible circuit diagram in this case I am not using LED display bars and I want to use breadboard and connector this circuit with very very various values of resencies so I want to know the specifications of resistance and LED is I want to use LED of red colour with 10 mm so I need help to know the value of resistances and there what it is

Kapil Kumar

Kapil Kumar

That’s Great, if you wish to buy any of the component used in this blog than you may visit our website,



Nice! I will try to make this for my water tank.

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