A new “tea bag” uses nano-fibers to suck contaminants and bacteria out of water, providing a desperately-needed, cheap solution for the billions of people without clean drinking water.Researchers at South Africa’s Stellenbosch University made the device from the same material used for the bags of the country’s popular rooibos tea. Inside the sachets are two tiny destroyers of all things unsafe: ultra-thin nanoscale fibers, which filter harmful contaminants, and bacteria-killing grains of carbon.

To use the device, a person simply has to place the bag in the neck of a water bottle, and the bag cleans the water as he or she drinks. A single bag can filter up to a liter of even the most heavily polluted water. The bags are thrown away once used.