Most spa towns or mineral water source towns have the stuff flowing free from a pipe in the town centre.
I always used to fill up for free when passing through Malvern. A supermarket not 50m from the source was selling bottles of mineral water from all over the world at the usual high prices.

Are there any spa towns in USA. I know there are hot springs in the Rockies but the water tends to be very sulphurous. Ive had other wild spring water that tasted like rust.
In wet mountain regions, springs can flow from cliff sides and they are usually OK to drink.