I wrote about that on our site a while ago - http://familyonbikes.org/resources/food.htm

As for water, we can't stand carrying camelbaks and getting even more sweaty. We carry a bunch of water bottles on our bikes and use them - between the three bikes and two BOBs we can carry 18 water bottles. (We use two of the water bottle cages for fuel bottles for the stove, so we really only have space for 16 water bottles, but that works!)

If we were passing through the desert and needed more water capacity, we would get a gallon jug and strap it on somewhere.