Branching into clean water: MIT's tree-slice filter purges bacteria and viruses without power

MIT researchers turned tree branches into water filters that removed more than 99% of E. coli and rotavirus in lab tests; after fieldwork in India, they designed a gravity-fed prototype that purifies about one liter per hour without electricity or imported membranes, using replaceable wooden discs—offering a cheap, accessible solution for clean water in low-resource settings, though real-world performance and durability still face challenges.