[p1w1]

then really you will need an r/o system to purify your water. What you need to do is work out what you actually want  and what you have, ie what size van do you have for carrying water, do you want to just pole the tops and trad the bottoms or pole the lot, your budget for gear, do you have room to store a tank and have a water supply to make the purified water if needed etc etc. If you don't need alot of water maybe there is someone near you who would sell you some.
paul