Do you ever find yourself wondering exactly how full your water tank is? With this project from Boris Landoni you can create your very own water tank level sensor using Arduino. This sensor allows you to track tank level trends, and even potentially automatically switch between tank water and mains water if your tank runs dry. An ultrasonic distance sensor is used to determine how far the water is from the top of the tank, and this is used to calculate the current water level. The output output is displayed on an LCD screen so that you can easily see how full your tank is! The possibilities for a project such as this are really limited to your imagination! To get started on this project check out the following link.