Otherwise, if you can locate a spring outside of the city and not surrounded by farms, that water should be good.
Supposedly there's a spring or some kind of running fresh water at the end of forbidden drive. But you'll have to call the park about that, and I don't know if it would be clean or contaminated.
Anytime you are considering a new source of water just do your best to determine any sources of contamination. Farms, cities, industrial waste, broadcast towers, these are your most common and worst sources of contamination. If you can find a spring out in the middle of a forest, that is your best option.