I hate starting blog posts this way, but I'ma exercise my one or two a year: I freaking love this idea. Researchers at MIT have discovered a new water filter: no charcoal, chlorine, screens, or ceramics involved.
It's a stick. Specifically, a stick of white pine.
Of course, it's one of those slap your forehead sort of thing. Of course some tree xylem could do this; it's what it's evolved to do: "The xylem has membranes with pores and other mechanisms by which bubbles are prevented from easily spreading and flowing in the xylem tissue." Turns out, those bubble stopped are exactly the right size to keep out bacteria like e.coli.
Sure, this is interesting to the home experimenter and even the survivalist, but this could be enormous for rural areas around the world who still don't have access to clean water. (How have we not figured that out yet.) We'd still need to account for protozoa and other nasties, but four liters a day is something.
Exciting, yes, but some are still skeptical. "Robert Jackson, an environmental expert at Stanford University, points out that at least as it stands now, the system doesn't do a good enough job at filtering out bacteria. He wrote in an email that filtering out almost all of the nasty bacteria is certainly helpful, 'but when you can have hundreds of thousands, even millions, of them in a drop of water, you don't want to rely on something with 99 percent efficiency. In a survival or short-term situation this could work,' he wrote. 'As a longer-term or global solution to the billion people on Earth without access to clean water, call me skeptical.'
Learn (and listen) to more at NPR's Shots blog: To Clean Drinking Water, All You Need Is A Stick