Good points being made by DTape, and OM here folks pay attention!

I second what they both said, and add; there are 2 'camps' in backpacking as far as water treating goes.

There are the chemical folks, and you know who you are <img src="/forums/images/graemlins/smirk.gif" alt="" />; and the water filter folks, and we know who they are <img src="/forums/images/graemlins/smirk.gif" alt="" />

Now, if you are trying to FILTER your water to remove everything possible in it that could cause you harm, then MECHANICALLY FILTERING is the only method that will get this done.

If you are attempting to make your water 'biologically safe for human consumption', if not filtering then you're pretty much choosing from the available chemicals or the Steripen.

Which begs the question, Why add more chemicals to water you are going to consume, instead of just mechanically filtering it clear and clean? The answer is weight, we as backpackers want the lightest, most practical alternative to drinking crud <img src="/forums/images/graemlins/tongue.gif" alt="" />

Ok, so from the available chemicals DTape made a pretty good assessment of them all, including the Steripen.

You choose your method based on the following: Region, water temps, turbidity or lack thereof, susceptability to local pathogens, your desire to rid your water of unknown chemicals. That's pretty much it in a nutshell IME. <img src="/forums/images/graemlins/smirk.gif" alt="" />