Prototype

 We hacked a calculator and attached it to a reed switch so everytime the magnet passed the switch the calculator would count this as one revolution of the wheel. We put in the function 1+1 =

 The magnet attached to the wheel

We attached the wires to the equals button

Connecting wires to the back of the calculator, connecting to a reed switch that reacts to a magnet we have place on our turning wheel. This wheel turns by water flowing through it. The reaction is counting how many times the wheel is turned, ultimately given us a clue as to how much water is being used.