I will show you how a water catchment system can work to run your entire home without any water from the outside world. This system does need an electric pump to maintain water pressure, so you do need to have electricity, eventually this could be on a solar system.
Technically you could probably drink this water, however we do not. It runs 100% of the plumbing in our house, the house has ZERO water from the outside world. The only source of running water in the house and on the property is supplied from this catchment.
TO make the water 100% potable, the system should have:
first flush filter
Tank feeder line not underground,
Also the house has a steel roof.