Arduino Water Gauge

A simple digital gauge to monitor the water level of two tanks.

Description

The Arduino Water Gauge is a compact and practical solution for monitoring the water levels of two separate tanks: one for fresh water, and one for waste. Using a SparkFun Pro Micro (or any compatible Arduino board), the system reads values from a float sensor to display a linear level for the fresh water tank and a simple full/empty status for the waste water tank via a float switch.

An I2C OLED screen provides real-time feedback, while LED indicators offer quick visual cues, blue for Bluetooth connection status, and red to warn of a full waste tank. Two buttons allow you to switch the Bluetooth module or the display monitor on or off as needed.

With built-in Bluetooth connectivity using an HC-06 module, the data can be remotely accessed for added convenience. Built on PlatformIO but easily portable to the Arduino IDE, this project is ideal for campers, boaters, or anyone managing off-grid water systems.

Features

• Dual Tank Monitoring Tracks both fresh water (with linear level) and waste water (with full/empty status).

• Compact OLED Display 128x56 I2C screen provides real-time tank levels at a glance.

• Bluetooth Connectivity Wireless data access via HC-06 module — great for remote monitoring.

• Visual Alerts Blue LED for Bluetooth status, red LED warns when the waste tank is full.

• Display & Bluetooth Control Two push buttons let you easily turn the display or Bluetooth on/off to save power or stay stealthy.

• Arduino-Compatible Built for SparkFun Pro Micro but works with most Arduino boards.

• PlatformIO & Arduino IDE Support Developed using PlatformIO, but easy to adapt for use in the Arduino IDE.

• DIY-Friendly Uses affordable components and a breadboard-friendly design for easy prototyping.

Hardware

• Sparkfun Pro Micro (or any compatible Arduino Board)
• Bluetooth module HC-06
• I2C Oled Display, 128x56
• 2 x led diode (suggested blue for BT and red for waste water)
• 3 x 330k resistor
• 1 x 100k resistor (depending on sensor range)
• 2 x push button
• jumper wires
• prototyping breadboard
• Float switch
• Fuel/Water floating sensor

Software

The project is built with Platformio (https://platformio.org/) If you are using the Arduino IDE, just copy the main.cpp file, rename it as .ino and import the required libraries.

Schematics

HC-06	Arduino
Rx	Tx
Tx	Rx
Vcc	Vcc
Gnd	Gnd

I2C Oled	Arduino (Sparkfun Pro Micro)
Sck	3 (Scl)
Sda	2 (Sda)
Vcc/Vdd	Vcc
Gnd	Gnd

Pro Micro pinout reference