I use a Shurflo 11.4lpm pump and a B.E.S.T type water filter, it does the job. I filter the water going in to the tank and the water coming out of it. There are several good wells along the way, with great quality water. Well 23,33,46, Georgia Bore and a few others I can't remember offhand generally produce good water. Stay sensible with your drinking water use, and you can just use well water for showering. You want to save as much weight as possible, and water is one of the things that soon adds up to being overweight, best to carry only what you really need, with a contingency plan for a few days extra.
We took 70 litres last time for two of us, but I'd reduce that by half if doing the CSR again to save weight.