From BBG:
“The CleanStream is a gravity filtration system that resembles an IV bag. Consisting of two Platypus bladders, two hoses, and one 0.2-micron-thick hollow fiber filter (w/a cartridge that’s good for ~1500L), this $90 system can handle bacteria, protozoa, viruses and particulate — i.e. the gunky yellow stuff that came out of the spigot at our campsite (see below).
The CleanStream is straightforward to use. After attaching the hoses to either end of the filter, you fill the “dirty” bag from your stream, spigot or other source (avoid shallow, still puddles!), and hang up the dirty bag, leaving the “clean” bag on the ground or somewhere below the dirty one. Instantly, gravity pulls the H2O down through the filter and into the “clean” bag. There’s also a clip on the hose that lets you pause the filtering if, say, you need only a smaller quantity of water in one minute vs. three.
