Your decision will be based on where you're camping, availability of clear water, whether you are sensitive to iodine, how much we... [show more]

Your decision will be based on where you're camping, availability of clear water, whether you are sensitive to iodine, how much weight you want to carry and other factors. Here's my take on the topic:

No filters or purification systems fully remove certain contaminants -- such as pesticides, herbicides, industrial metals, etc. If you're in an area where you suspect this is an issue, check with the park service and find out about any unsafe water sources.

I've carried both a filter and purification tablets. A .2 micron filter is probably good enough for most scenarios, because it catches bacteria and protozoans (some of which are quite nasty). However, even a .2 micron filter won't catch viruses. Iodine will kill viruses and bacteria, but some protozoan cysts are resistant -- such as Cryptosporidia (nasty). I have backpacked for up to 12 days consecutively on the trail in both New Mexico and Virginia, drinking only water from streams & using a Katadyn filter (.2 micron), and never got sick.

Now here's an idea: Try the Steripen ultraviolet purifier. I was at first reluctant to make this recommendation, but after doing some research, I think it's effective at deactivating bacteria, protozoan cysts, and viruses. This model has a prefilter in case you can't find clear running water: http://www.rei.com/product/761906

Reading user feedback, the main problem some people had was with battery longevity -- which seemed to be resolved by using lithium batteries. Here's the results of a controlled test of the device using EPA test standards:
http://www.steripen....ape_study.pdf
I'll be using one of these next time I'm on the trail.

For more detailed information on this issue, read the expert advice tab here: http://www.rei.com/product/720265 [show less]

Is what I use.

and it is PRETTY! Looks simple to use, too. http://www.campmor.com/webapp/wcs/stores/serv
let/ProductDisplay?productId=30924571&m..
. [show more]

and it is PRETTY!
Looks simple to use, too.
http://www.campmor.c...d=40000000226

Ever used one? I haven't. [show less]