If you're putting in a cistern to be your primary source of water (full potable use), be aware of your roof materials. Don't use asphalt shingles unless you're only planning on collecting just from the solar panels and can segregate the two (panels are mostly glass so they're fine). Use a metal roof or look for something that's NSF certified. Make sure you use a pre-filter before water goes into your cistern to keep out large organic material (leaves, sticks, bugs, etc) that might wash off your roof. Then there are plenty of options for treatment/filtration as it comes from tank into your house, many of which are easily wall mountable and use a couple filters (sediment/carbon) and UV light for disinfection. Water will be every bit as good, if not better than your municipal water, which you could still have as backup.