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Understanding the Water Level Indicator Circuit: Working & Applications

Imagine being at ease of getting notified when your tanker is full. You can save up water and contribute to the world with this little effort. In fact, you do not even have to do any of the efforts when you can use a water level indicator circuit.

Yes, such circuits do exist and have vast applications. The role of this circuit is to notify you about the level of water. As you know, we cannot live without storing sufficient water for household needs. Since these tanks are huge, you cannot always check the water level in them.

However, this is not a problem since you can use a water level indicator circuit. You can go for a circuit with a 555 timer. It is more easy to use and also accurately indicates the water level in your tank. Unbelievable how a small device can help you save up water and time simultaneously! You can quickly turn off your pump when the tank is full after the circuit notifies you of this.

Now it’s time to go in-depth with the water level circuits. We are starting with the definition of a water level indicator!

What is a Water Level Indicator Circuit?

The water level indicator circuit is a type of circuit that sensors the water level in tanks, swimming pools, and even dams. Such a circuit is beneficial for saving up water and helps you contribute to saving the world from the possible water crisis in the future. 

Working of Water Level Indicator Circuit

Now, it is important to know that a water level alarm works differently as per the water level. If the level is low, there are some considerations that you need to know. In this section, we are going to talk about how this circuit works in low water levels:

  • There is an NPN-type transistor that plays its role as a switch in the circuit.
  • The circuit has 0 voltages in the beginning because you will keep the transistor turned off, which does not allow any current to pass through the circuit.
  • You also keep the LED off.
  • Now, wait for the water level to approach a marking called A in the tank you are working with. 
  • Join the positive terminal of the battery to the transistor. Now when the transistor will receive the voltage from the battery, it will turn on.
  • When you turn on the transistor, it will allow the current to flow and move toward the emitter from the collector. It will also turn on the LED.
  • The resistors are also working with the transistors in this experiment. Their role is to increase the current that passes through the circuit. 
  • The standard voltage that turns on the transistors is to be 0.7 volts. It is important to regulate this voltage since it can burn the LEDs due to excessive charge. 
  • Now, a similar thing happens when you are experimenting with marking B. The voltage from the battery goes to another transistor. 
  • The current flow after it has been turned on, and it glows the other LED. 
  • The buzzer present in the circuit will slightly make a noise, like a beep, to notify that the water has reached its maximum limit, meaning the tank is now full. 
  • One thing that you need to remember is to keep the wire that brings the voltage from the battery to the transistors bigger in length than the others. 

Circuit Diagram of Water Level Indicator Circuit

If you have a physics background, you know circuit diagrams are highly useful when it comes to understanding the functions of circuits. You learn about all the important components and their roles in the circuits. So, a water level indicator circuit also has a circuit diagram that we are going to discuss below:

  • The job of this circuit is to observe the water levels in a tank or maybe a reservoir. 
  • Now, the circuit will quickly turn on the pump to fill the tank when it detects a low water level in it. How impressive, right?
  • It has 5 LEDs that glow on five different water levels in the tank.
  • When the tank is full, the circuit will beep, indicating this and stopping the water from brimming out and wasting. It will turn off the pump for this.
  • Some circuits also use probes in place of LEDs that you need to position at different distances to avoid any damage and mishap of the circuit.
  • However, the space between these probes should be the same, and you need to align them in the form of a stack. 
  • The probe which is positive will be under the rest of the probes. Similarly, the positive voltage is beneath the tanks, and other probes are on top of it. 
  • You need to connect the second terminals to the transistor, and you can use a resistor for this purpose. 
  • Now here’s what happens: In case when maximum water is flowing, it will make the current flow toward the probe present at the bottom. 
  • Also, it will reduce the voltage. It will turn off the pump when the water level reaches the maximum. 

Water Level Alarm Circuit

These alarm circuits also work similarly to water level indicators. However, we can use a circuit diagram to fully understand their working:

  • You need to combine a water level alarm circuit with a regular alarm. Now position it on to of the electronic water level circuit that will notify a person inside their home about the level of water in their tank.
  • For the electronic alarm circuit, the probes are important because they work efficiently with the microcontroller’s pins. 
  • The purpose of these pins is to let huge amounts of current pass toward the speaker from the microcontroller. It can also command the LED if you are using a microcontroller which is supportive of that. 
  • The electronic alarm circuit will keep updating the person about the water level. It greatly helps when the tank needs to be filled, or the pump needs to be turned off. 

Water Level Alarm Circuit using Level Sensor


Did you know before that you can use water level alarm circuits with level sensors? Well, this post is going to be ground zero for you to understand how versatile these circuits can be. Here’s how you can use water-level alarm circuits with sensors:

  • You need to grab a special liquid-level sensor for this purpose.
  • It gives a sound as soon as it detects a change in the water level. Even if it’s a single drop, the sensor will respond.
  • It is a simple circuit, and you just need Physics 101 for its construction.
  • You can rely on the LM1801 IC for this because you can also use it as a comparator, and it gives an impressive amount of current.
  • The sensor will beep when it detects the water level is lesser than the default level in the tank.
  • You can even construct these sensors on your own with PCBs. All you need to focus on is etching to make such a sensor.

Applications of Water Level Indicator Circuit

Some of the major applications of water level indicator circuits are:

  • These are important for inserting in tanks and hotels; factories and house owners completely rely on these circuits for water saving.
  • Different motor types are supported with these circuits. These are single-phase motors, three-phase motors, and submersible motors. 
  • You need different circuits for monitoring the water level in different tanks. One circuit cannot monitor two tanks.
  • Such circuits can also identify the fuel level in industrial machinery and consumer vehicles.

Advantages of Water Level Indicator Circuit

  • These circuits are affordable and easily accessible for the users and producers.
  • The circuit beeps and gives alerts to the user when they need to turn the pump ON and OFF.
  • You can easily store and save water by relying on these circuits.




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