I have a 5000 litre underground rainwater tank which collects almost everything that comes off 200 sq m of slate roof in a village in Devon, which amounts to over 200 cu m per year.   It goes through multiple stages of filtration and then a UV steriliser. So it is fit to drink, though in fact we have mains water piped to the cold taps for drinking. Everything else gets fed from the rainwater - loos, washing machine, dishwasher, hot water system.   The water is noticeably acid