A wonderfully low-tech and low-cost, MIT-designed solution for developing countries, this homemade water filter requires just a few common and inexpensive items working in conjunction with a small piece of tree.

Certain kinds of sapwood are particularly capable of filtering out dangerous E. Coli bacteria, effectively using the same natural process by which trees move water through their own trunks and branches while straining particulates. These DIY xylem filters use the branch’s organic ability to filter out particles down to 20 nanometers in size, combined with a tube and some glue and/or a metal strap to tighten the entire little apparatus.

Other plants may be even more well-suited to the process than those already tested by MIT researchers. “Today’s filtration membranes have nanoscale pores that are not something you can manufacture in a garage very easily. The idea here is that we don’t need to fabricate a membrane, because it’s easily available. You can just take a piece of wood and make a filter out of it.“