4 Answers

Could be a very expensive process,read here...http://healthvermont.gov/enviro/water/lake_river.aspx

You would also need to contact the local authority regarding legality.

If you live at a lower elevation to a brook, creek, spring, etc. you can deliver the water to the home by gravity, as far as I know, for your own use, not commercially, you are breaking no laws.  Check with Mother Earth News, for details of how to do this...

Nothing to stop you using rainwater to drink, shower, wash clothes and car. It's probably purer than river water but would still need to be purified.

A lot easier to drill a water well. Use sediment filter first, couple carbon filters then ultraviolet light to kill viruses-bacteria. But get your water tested first thing.