Restrictions are mainly on commercial and especially agricultural use. It's not that bad for residential systems. https://www.worldwaterreserve.com/rainwater-harvesting/is-it... But in Georgia, you can only use the rainwater outdoors. So you can't legally flush your toilet with it.
Some municipalities have ways to handle the second (as you have homes that are on well water but city sewer). Usually it's a flat fee based on occupancy or square footage.