An MIT
study shows tree branches can filter 99% of bacteria. There's a real potential for low-tech clean
water. Here's the best quote from one of the co-authors:
"There's huge variation between plants," Karnik says. "There could be much better plants out there that are suitable for this process. Ideally, a filter would be a thin slice of
wood you could use for a few days, then throw it away and replace at almost no cost. It's orders of magnitude cheaper than the high-end membranes on the market today."