Personally, I fail to understand how anyone could or would want to avoid drinking water from the fresh water tank. Even in moderate temps with moderate exercise my wife and I each drink about a gallon of water a day. If we stay in a National Park or remote area for even just a 10 day period that would total 20 gallons of bottled water. That would not include the water used for washing and rinsing dishes and certainly not for taking showers. I would really not want to use questionable for either of those.
Aside from the tremendous waste of plastic and the high cost, it just does not seem feasible to buy bottled water for drinking. I cannot even imagine trying to buy bottled water at some place like one of the general stores in Yellowstone. The cost would be more than camping fees and fuel costs combined.