I recently responded to a forum thread at BackpackingLight.com regarding the best lightweight options for purifying water . I suggested trying the SteriPEN and the Sweetwater Anywhere in-line filter (4.5 ounces), both of which I own and use.
In another response to the question posed, Carl Kinney recalled a Backpacker Magazine article that suggested three main factors for people getting sick (noting that statistically your chances of getting sick from unfiltered water are small):
- Bad water: drinking from live stock ponds and sources around campgrounds and heavily used trails.
- Poor personal hygiene.
- The ability of your immune system to fight off bacteria and viruses.
I need to know more before I will recommend not filtering. For a long hike such as a AT or PCT , perhaps eliminating a filter to reduce weight is an option for some. But for shorter trips, having some kind of water purification system makes sense to me.
Be safe. Be light. Be one with the pack.