http://www.collective-evolution.com/2014/03/09/florida-makes-off-grid-living-illegal-mandates-all-homes-must-be-connected-to-an-electricity-grid/
There a special magistrate ruled Speronis was not guilty of not having a proper sewer or electrical system; but was guilty of not being hooked up to an approved water supply.
It's a city code about her water supply. She's collecting rainwater off her roof, treating it. Then using it. I wouldn't advise doing that inside any city limits.
They don't want her using rainwater because she pays no water bills and sewer is billed based on water use