We each have our vision of how we want to travel....for me carrying a full 26 gallons in the Hawk is like keeping as close as possible a full tank of fuel while in the boondocks...so that I if I need it, I have it....on pavement, more options to replenish both...MPGs, questionable how much a couple of hundred pounds will affect MPG, since most of our mileage is determined by pushing the Tundra/Hawk weight/sail down the road and of course our speed/RPM range..
Bottom line is do what makes you worry free and enjoy the trip! Have fun!
I agree. Using my house water that is filtered and through a water softener, I have a known source of water that is trusted. If water is needed on the trip then I search out opportunities. Some people bring a filter to run it through as it fills. Some have a inline filter that filters as you use it.
It comes down to individual preferences how you use the water and what trust you have toward the water being used. Some add a little bleach when filling up on the road to the tank supply.
Others bring bottle water supply and consume that and use the tank water for other usages.
It's all good, water is a necessity, use your method of choice.