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Arduino project · Water and plants · Easy

Water Tank Level Alarm

The alarm sounds when the tank is nearly full; green means there is still room.

What you will learn

  • How a water level sensor reads depth
  • How to set a high level alarm
  • Why calibration matters

How it works

The water-level sensor gives a percent level. Above 80 % the buzzer and red LED turn on. Below that the green LED shows normal level.

Try this next

  • Add a low-level alarm too.
  • Switch a pump with a relay.
  • Show the level on a bar of LEDs.

The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.

1Choose your Arduino board
2Build the circuit
Parts: sensors and actuators (tap to show or hide)

Try the inputs (virtual sensors)

Pins (you can change them)

PartArduino pin (change it here)How to wire it

Every wire, one by one

Red rail = 5 V from the Arduino 5V pin. Black rail = GND. The coloured wires carry signals. Match the wire colours on the drawing to this list.

#ColourFrom (part and leg)To
3Define the sequence

Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.

4Arduino code





5Parts list and where to buy


Quantities come from the parts you added. The store links open a search for that item on Robu.in, Amazon.in and ThinkRobotics, so you always see what is in stock today. Check the model, voltage and price before you order.


#ItemQtySearch termBuy / compare



6Export








The PDF has the circuit sketch, pin table, every wire, sequence, full code, the parts list with store links, do’s and don’ts for each part, and the safety notes. The project file lets you come back and keep editing.



7Learn: do’s, don’ts, cautions and tips





In the real world
A tank with a level alarm
Change the water level. The tank in the real scene fills or drains and the alarm rings at a dangerous level.
Tip: use the gold tab at the bottom of the circuit drawing to pull the real-world view up over the Arduino board. Your parts stay visible above it, so you can press a button and watch the real scene react.