my wife is a home builder - pretty high end one - and she bulit our house. that said it was her first time at trying "green luxury" so we did learn a lot. the goal was to make the home as self reliant as possible but with it all "hidden" and seamless to the user. We have a two floor home, upside down built into a hill. so street level (well 8 feet below street level) is the top and first floor. There is a dug out "basement" second floor with a den and kids rooms and another office but half of that floor has a two foot thick rebar enforced wall to create a cistern for rain water. consider it like its own rooms on that floor but without access from that floor. It functions as a huge tank. it's under the garage, kitchen, and a part of our dining room which are all top floor along with my office, living and our master bedroom and bath. Access is a hatch in the garage. Our roof line is a butterfly roof then a shed roof, so like this --> \/ \ Note \ / = butterfly and \ = shed.
each of those roof lines forces water to the "V" of the butterfly roof and the outer side of the shed roof. There is a traditional gutter on the shed roof and 3 drains in the trough of the butterfly roof. The drains are 3-4 inch PVC pipe that run through the walls and carry the rain water to the garage cistern where the water flows in. The gutter on the shed drains water to the part of the home that is the subfloor between first and second floor and then runs the same 3-4 inch PVC pipe to the garage through the subfloor across the house. That shed roof gutter does not go all the way down to the ground to release water.
Now all water is in the cistern which is coated with a potable water grade coating that is water proof. The gutter and drain system has a filter to collect large debris and dirt before dumping into the cistern. From there we have an aerator to keep the water fresh, no light so no algae, etc. the cistern is sealed so no critters, and we have a sensor for our home assistant smart home stuff to show amount of gallons remaining.
When we use it, the pump pushes water to the pressurized tank, then pushes the pressurized water through two filters for particulates and then a UV light filter and out to the home. From that point forward it acts no different than "city" water - except - it tastes great, and it does not have any minerals/deposits including additives or calcium, lime, or anything else to cause scale or spotting issues. Our dishes are spotless with regular detergent, our shower glass doesn't spot, just really really happy with rain water.
I do want to add RO to the drinking water, given the recent discovery that even rain water has PFAS, so that was a major downer because I thought we were avoiding all the crap in city water. we do avoid a lot, but probably not everything if those studies are accurate (which I assume they are).
she did consult with a distributor of products, a one stop shop if I recall. we originally had a thick liner but decided that was a mess, so we painted on the water proof potable water grade coating instead. but special items are the tanks, the coating if you need one, the pump, sensor, the drain filters, the pressure tank and the filtration system.
it's super cool.