Despite the negetive feedback about bladders / Nalgenes and water filters, we carried all three for our '04 thru hike. We used a Camelbak Unbottle (or just a Camelbak bladder if you want yours in your bag). Filters were a life saver on the trail. I can’t count the number of times we filtered water for chemical hikers. The other advantage with a filter is you can get your water from almost ANYWHERE. There were several occasions where there was no water and we had to filter water from a rain puddle on the trail or from a puddle on top of a mountain. Plus, filtered water always tastes better if you like having good tasting water.
We carried the Nalgene bottle through the Smokies because we put boiling water in them and put them in our sleeping bags to keep us warm. After the cold weather was done, we sent them home. Invaluable trick when (not if) the weather gets colder than you anticipated. It’ll keep you warm for something like 8 hours or so. You can’t do it with 3 liter soda bottles or (most) bladders.
We did see a lot of people carrying platypus bags to fill and bring back to camp. Handy when you don’t want to get back up and walk .5 miles back to water for more.
Definitely carry at LEAST the capacity of 1 liter… 2 or 3 is much better.
Dave and Miranda