I use the steripen and I love it, the draw back on the pen is the water has to be reasonably clear, so you would have to prefilter murky water with a bandanna or t-shirt. Also you can't leave the batteries in the unit for storage or they will be dead over time. It has a small internal drain if left in there. I use the thing, then tale the batteries out until the next time I need it. There is some more info if you search for it on the site.

http://forums.equipped.org/ubbthreads.ph...=true#Post92710
http://forums.equipped.org/ubbthreads.ph...true#Post104842