They've sold our water to for-profit groups, some foreign. This includes any rain falling on our property (chance there for gravity related charges as well). My ex-BIL had to pay some charges for rainwater which ran off his warehouse roof into the nearby stream for some odd reason. They do allow us, indeed encourage us, as individuals, to have water butts which they do not not charge us for using.

Incidentally. hot-air balloons depend on the cold air sinking to enable them to rise, so you haven't escaped the gravity charges that way.

Penny