$100, 7.4 ounces, www.cascadedesigns.com/MSR
Updated from a 2008 model that had some filtration problems, the newest iteration of the Hyperflow is now slightly more successful—clogging less easily than its predecessor. The system is still most effective when used in relatively clear water. The Hyperflow is compact and easy to assemble, requiring only a plastic tube attachment—one end to the prefilter and the other to the pump. Though effective against protozoa, bacteria and particulates, the Hyperflow does not remove chemical toxins, viruses, taste and odor. It can be assembled and disassembled quickly, making cleaning and backflushing easy. Because of its small spout, the Hyperflow fits snugly into the opening of disposable water bottles. This system filters three liters per minute—the fastest system tested.