What You Need
The main component required to make this project work is something called a flex sensor. The buoyancy of rising water levels will bend the sensor. As the sensor bends one way or the other, current values will increase or decrease accordingly. The sensor’s position can be read with a simple Arduino program and can be powered via either the Arduino’s 3.3 or 5.0 volt pins.
Here’s the complete list (refer to the photo in Figure 2, Water Level Notifier parts):