My city is nestled between a rain forrest and lots of natural springs. If we put our water through the normal cleaning process it would come out dirtier then it went it. We also have a few damned lakes we are having to release water from because we got so much damned rain this past winter.
We have a flat rate we pay for water, sewage, recycling, and garbage pickup and are only charged more if we use a certain amount of water. Mostly just people who water their yard or have a personal pool have to pay the higher fee.
Just wait until you learn about friction!