Newbie into rainwater harvesting. A couple of queries: 1) Any tips on calculating storage tank size? 2) Does the "system" somehow connects back to mains? 3) Is it recommended to install a filter to rainwater harvesting system? 4) Generally, always full or empty? 5) What kind of maintenance...

Hi, Seeking volume or semi-custom builder in victoria(east), which have existing double story wide floor plans. Seeking 18-20m wide homes with depth of 12-15m long. Or if you know of any custom builder, please reach out. Thanks