[KimNTerry]

It depends on a couple of things.
How close are you on weight limits? Water weighs 8.3 pounds per gallon.
Is water available at or near your destination?

If you have the weight capacity/ratings and water is not readily available at or near your destination then fill'er up at home.

If you are close or over on weight capacity and water is available then put enough FW in for pit stops on the road (10 gal) or so and leave it at that.

If you are close or over on weight capacity and water is NOT available then put enough FW in for pit stops on the road (10 gal or so) and do your homework on the closest place to your final destination that you can get water. Many small towns have low priced dump and water as they want your tourist dollars. Leadville for sure does. I use the dump station there before heading home. If going up Poudre Canyon (Highway 14) I don't know of any water available up there.

You have to balance availability, capability and convenience.

All that being said. I usually haul the water from home.