Arduino project · Water and plants · Medium
pH Water Monitor with LCD and Warning LEDs
Shows the pH of the water. Green means safe (6.5 to 8.5), red means too acid or too alkaline.
What you will learn
- What pH means and what the scale is
- How a probe gives a voltage
- How to build a good/bad indicator with two limits
How it works
The LCD shows the live pH. The green LED is on between 6.5 and 8.5. The red LED is on above 8.5 or below 6.5. Use the pH slider to try lemon juice (2), tap water (7) and soap (10).
Try this next
- Add a buzzer for pH outside 5 to 9.
- Log the pH every minute.
- Add a pump that doses neutralizer.
The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.
Parts: sensors and actuators (tap to show or hide)
Try the inputs (virtual sensors)
Pins (you can change them)
| Part | Arduino 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.
| # | Colour | From (part and leg) | To |
|---|
Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.
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.
| # | Item | Qty | Search term | Buy / compare |
|---|
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.
In the real world
Testing the pH of water
Move the pH slider. The marker moves along the pH strip from acid to base.
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.
- pH sensor = acid or base
- LEDs = warning / OK