The filter I've been looking for. It's lightweight, multi-functional, easy to use, and difficult to break. That makes it the perfect piece of gear!
I bought this filter in September 2011 to replace my Katadyn Hiker Pro. After my bad experiences with the Katadyn and SteriPen and my ambivalence toward my MSR Miniworks, I wasn't eager to be disappointed again. I spent a couple hours taking apart ever filter in the Bozeman REI before this Sawyer gravity filter caught my eye. I had been skeptical years earlier when I had first heard of it. "One Million Gallons Guarenteed" sounded like a scam, but if they guarenteed it and it didn't deliver, then I'd return it without remorse. I used it for my three day solo bike tour in Utah and Colorado (which saw some very dirty water), four nights (solo) in the White Mountains, and a six night, two person trip in the Absaroka Mountains.
Admittedly, it's only seen use on three trips so far, but I'm optimistic about it's durability and longevity. For starters, it has no moving parts, which is what broke on my Katadyn, and after my SteriPen failed I'm more inclined to prefer the lowest tech option available. It doesn't have a ceramic filter either, which is what broke on my MSR. Essentially, there's nothing to break. But a filter also has to last inside or it's no good. The six night trip was a good test of its filtering capabilities. After most uses I would back-flow half a liter and every other night or so, a little more. When I got back after each trip I used the sink attachment to pressure back-flow the filter to clean it even better. So far it still has a good flow rate. I'd recommend squeezing the 'dirty water' bag to get the flow going and then let gravity take care of the rest. The bags themselves are very durable, as are the hoses.
Another plus for this filter is its effeciency. It's lightweight for what it has to offer, it filters with virtually no effort, and it's easy to maintain in the field. This is more than a filter, it's also a water carrier. The 2L system has 2 bags which makes 4L total; there is also an 4L system which allows for 8L of water capacity. With a bitevalve (not included but a mere $3 or so) it's also a personal hydration system, like a Camelback. After filling, give the dirty bag a little squeeze to get the flow going and then sit back and wait a few minutes. It doesn't get any easier than that and now I don't even have to work during my water breaks! Ahh, luxury. After I have my bag of clean water I sometime reverse the bags (I usually used a small slope rather than a tree to get the gravity difference) and let it back-flow a little.
As a rule this filter has been a great addtition to my kit. Besides its obvious functions, it's nice to be able to carry so much extra water when putting out a fire, or camping away from my water source, or just to have all my water on hand in the morning so I can get breakfast going without a delay. My single complaint comes from when I first used it as a hydration bladder in my backpack. I was hiking along when I felt water dripping into my pants. I tore off my pack and found two liters of water flowing over my clothes and sleeping bag (all protected by water resistant stuff sacks, but still) and soaking the inside of my bag. The hose had come off the bag. The attachment is held by friction, which obviously didn't work. I'll need to get some decent zip ties to fix the problem. I may try to find a female end to permaentally affix to my hose so it attaches male-female, instead of with friction alone.
It costs more than some filters and less than most. Considering its functionality beyond mere filtering, its terrific durability, and I expect (though only time will tell) its appropriately guaranteed longevity, this filter is a steal!
I love this hydration system and haven't been this excited about a new piece of gear in years! It does everything it should and more. It my #1 recommendation for a filter whether you backpack or tour, solo or in groups. This is the filter I've been looking for.