Water Filters For Hiking
I always carry a hikers water filter with me in my camera bag. A couple years ago when I was hiking the Siyeh Pass in Glacier Park (a 10.3 mile 1 way hiking with an elevation gain of 2440 feet), I ran out of water about half way through the hike. Rather than drink water from runoff and take a chance on getting Giardia, I opted to go without water the rest of the way (about 4 1/2 miles). It was a very hot day and I got dehydrated and about 2 miles from finishing my legs froze up.
If you are planning a hike over a couple miles you may want to consider carrying a water filter. They are about the weight of a small bottle of water and could save you from some real problems.
Check out the filers in the ad on the lower right of this page.