I just took the MSR MiniWorks EX Water Filter on a 4-Day backpacking trip in the Grand Canyon. My filter was the primary method of water for eight people. I freaking love this thing. It was so easy to use, and I appreciate the fact that I can attach it directly to the top of my Nalgene bottles.
The ceramic/carbon filter effectively removes bacteria and protozoa including giardia and cryptosporidia and on top of that…bad taste/odors which can be caused from things like chlorine, iodine, pesticides etc. Though I don’t recommend trying to filter pool water.
It pumps just under a liter a minute and weighs about 14.5 ounces so while someone might argue that it weighs too much for you ultra-light backpackers, this piece of equipment was worth it. My only complaint? When one of my fellow backpackers was using it the little float at the end of the hose decided to detach and immediately float down the river. Obviously, that is the least important part of this product and probably really easy to replace or create a makeshift one.
Last thing: The filter is incredibly easy to clean, remove the ceramic filter and scrub in upward/downward strokes. Supposedly the filters last for about 2,000 liters; that’s a mighty long time.
You too could own this magic piece of equipment – REI sells them for $89.95 here: MSR MiniWorks EX