Mountain Safety Research HyperFlow Microfilter Water Purifier

Much to recommend this water filter
I'm perplexed that all of the prior reviews gave 5 star ratings when two of the reviews were highly critical in the narrative. In this case I am giving an unqualified 5 star rating. This Hyperflow filter replaced my previous MSR Sweetwater, on which a piece of plastic that anchors the pump broke rendering it unuseable. Before that I had a PUR (now Katadyn) Hiker which was an effective filter, but heavier and more difficult to pump. The Hyperflow has a very simple pumping mechanism that is both effective (it takes less than a minute to fill a typical water bottle), and ergonomically designed, so you can comfortably fill a number of bottles in one sitting without your hands going numb with fatigue. The inlet hose has an attached pre-filter to keep grit from getting to the pump; the pre-filter is effective but it floats on top of the water (particularly in a free-flowing stream) so I typically use a rock to pin it below the surface. The outlet hose comes with a quick-connect cap that screws on to a wide-bottle Nalgene (I use it on a high-capacity Nalgene Canteen). This is an outstanding feature - you can fill your bottle without having to try to hold it and pump at the same time to avoid a spill (a gymnastic exercise with both my previous water filters). The quoted weight must not include the two-sided pouch that comes with the filter (see pictures) - one side is mesh, holds the hose, pre-filter, and cap, and has sewn-in instructions how to disassemble and back-wash the filter. The other side holds the filter and is coated fabric so the filter doesn't dribble water into your pack. The total weight of my filter, including attachments and the pouch, is 10.8 ounces; that still comfortably beats any full-featured filter on the market. You can cut weight further with a Steripen or MSR Miox purifier; I owned a Miox and it must have been effective (I never got sick) but there's nothing like the clear pure water you get out of a filter. I live in the Northwest, land of many deer, beavers and other creatures so it is critical to purify the water. Every trip out, I'm shuffling what goes into my pack, but one piece of equipment that ALWAYs is included is my Hyperflow filter.

Works great for the first 10 liters
I was really excited to get this pump, great throughput and low weight, and even field cleanable. But even backflushing every 4 liters it became incredibly hard to pump very quickly, and then it broke while we were applying a lot of pressure trying to pump. I was using it mostly in the sierra where the granite dust wreaks havoc with water filters. Katadyn Hikers and MSR SweetWaters all failed on me too, but lasted quite a bit longer. I also found the backflushing process really annoying, you have to take it apart and flip around two O-rings.

Great filter
I have used this filter in the field for months and it is my favorite - it is small, light and fast. I own 3 others from various manufacturers and keep grabbing this one. Back flushing is not to hard once you've done it a time or two.