On our rural property, we opted for rainwater catchment and pond water backup because the rural water utility gets its water from a sand point well next to a river full of ag chemical farm runoff. We use a series of sediment filters down to 1 micron, followed by UV light, followed by a carbon block filter. The drinking water system then further purifies it with RO, followed by remineralization cartridges. We use RO for the drinking water because our rainwater contains mercury from coal burning power plants.