“A capacitive liquid sponsor relies on the fact the the capacitance or charge between 2 metal plates will change (in this case increase) depending on what material is between them. This allows us to create a level sensor that is safe for use with any liquid, this one will be used in a buggy with gasoline (petrol). One plate is hooked to ground. The other connects to pin 23. There is a 820K ohm resistor from pin 22 to 23. The sensor works by charging the capacitor (the water bottle) and measuring how long it takes to drain through the resistor.”