On the trail, filtering water always feels like a chore to us -- like having to wash dishes or take out the trash. So we sometimes like the idea of water bottle filters. You can just scoop and go. But, in the past, bottles have had sluggish flow rates, and you could sprain your cheeks trying to draw a drink.
Sawyer seems to have solved the issue with its Innova Stage 2 filter. Borrowing technology from kidney dialysis equipment, the Stage 2 has fibrous tubes that block biological contaminants (e.g. bacteria, cysts, protozoa) without obstructing the flow of water. Plus, a pre-filter removes lead, chlorine, bad tastes and odors. We found that the bottle functioned well over the course of several hikes this summer and fall, always offering a steady, satisfying flow of water.
Our only wish is that the filter took up less room in the bottle so that it could hold more than 20 ounces. (A standard Nalgene bottle holds a bit more than 32 ounces.). On hot days -- with long stretches of trail between water sources -- you could easily go a little parched since 20 ounces won't last longer than about 30-45 minutes, meaning an extra water container becomes a serious consideration for a backup refill.
Suggested retail: $39.99