My favorite filter - Platypus Gravity Works Carbon Element

Not the most lightweight filter, but definitely the easiest to use. Good for getting water to the whole camp quickly. I got roughly 2 years of frequent use and 3 years of light of of my previous filter. I never kept up with the amount of gallons filtered but I can assure you it is many. My hiking group is 3-6 adults. I use this filter to fill a 5 gallon collapsable cube that everyone uses, and keep a 4 liter bag filled as a night time backup if the cube runs dry. In the 5 years I've used this filter no one has become sick from its use, which was mostly in the southern portion of the Appalachian mountains