Wow Freedom – that is a huge subject! Berkey and Katydyn filters are great – different sizes and uses. I have various versions of both. Rain water can be filtered through one of their models. My well water has an alternate hook up don’t currently use but it will need the use of electricity from my solar generator to filter enough water to fill the expansion tank.
My pool is a different story. Versions of Berkey and Katydyn can filter it for drinking. I have lots of shock, calcium chloride etc stored and solar skimmer and circulator so it doesn’t need electricity even now to use. The circulator has a solar panel on top and with a few changes to it, it can even pump water out of the pool. (I use one in the pond when I need to pull water to water plants or fill livestock tanks). I think I spoke of them here before but gosh knows where. I envision the pool for a backup water storage not for swimming necessarily – think we will be too busy comes to that.
This company has many, good single use water test kits for the basics. Might be handy to stock a few for the most common issues. Water quality/testing etc is a huge science all on it’s own.