Rain water is filthy, much worse from a cistern... you'd be better off
drinking from your neighbor's pond. In agri areas well water is
loaded with chemferts and bacteria from livestock.
All the water in our house has been treated with UV plus all our
drinking water comes through our RO filter. The water we drink is far
cleaner than any you can buy.
Municipal water companies only test the water leaving their plant, and
then it may travel through many miles of filthy antiquated piping...
the piping in most peoples homes is disgustingly filthy. And the water
from their hot water heater is excruciatingly filthy because hardly
anyone shocks their hot water heater regularly with chlorine bleach...
the morons set their dishwashers to sanitize, that sanitizes
nothing... that water is not nearly hot enough to kill all the
nasties... they'd be far, FAR better off to hand wash... insulated
rubber gloves are cheap. No residential dishwasher sanitizes... only
top of the line commercial dishwashers are capable of sanitizing
because they blast everything with 230degF live steam.