What I am considering doing is using a cistern type collection system. In my area, most of the rain falls in the winter and early spring. Then we go 6 to 8 months with unpredictable amounts of rain. So, old timers in this area have done for many years, is have good gutters installed on their houses and outbuildings. Then have the water routed to go into a tank of some kind. I am buying a tank of poly 3,000 gallon capacity to be my above ground cistern. The water will be filtered in a filter similar in some ways to what you describe. If the first tank is a success I will add three more for a total capacity of 12,000 gallons to get us through the dry months. I want to make certain to have plenty of water for our yard, garden and orchard. If power goes in a severe problem we would have lots of soft potable water. My main concern for immediate use is for irrigating our food growing plants.