[mugwump]

If you're on foot I feel pretty safe recommending a Steripen. It uses UV light to scramble the DNA of any nasties. I've used it for about two weeks total in Honduras and hiking the Corcovado in Costa Rico but my daughter has used one for the last 7 months in Vietnam, Tibet, Cambodia, etc. Ours are the older ones that use two CR123A, but they have new versions that use NIMH AAs, solar power, hand crank, etc. The daughter is pretty suspicious of tech solutions but hasn't been let down by this device. She hiked to the Everest base camp where the sanitary conditions are questionable ("f***ing gross" was her technical description) and she was fine when even the Sherpas had the squirts. We both prefilter with paper coffee filters if the water it's goopy. She carries a Surefire toe-popper full of batts on really long segments--she really hates chem treated water.

Pros: no chemical taste; works as well on cold or warm water; only takes 60/90 seconds for 16/32 oz.; small and light; (huge to me) if you're in an area where water is plentiful you don't need to hump excess water because you can get another 32 oz in 90 secs. I'm convinced the "chem" people I've hiked with got sick because they rushed things when thirsty and didn't give the iodine or whatever time to work.

Cons: batteries, only 50 liters per set (although if you're recharging less of an issue); it's a device, and devices break--you need Aquapure as backup.