i usually carry a camel back 64 oz full of water if im going to be overnight in a dry area. otherwise i carry it nearly empty and pump what i need for the next leg of the trip. my pump weighs about the same as a 12oz bottle of water sooooodo the math.

3 of us went on a two day overnight tip in 90*F heat 2 weeks ago and no fill up was available so we carried and used 2.5 gallons of water. we were totally dry when we arrived at the truck!! and thirsty