Gum from the prickly pear cactus naturally filters contaminated water. Scientists are researching how to do this on a large scale for impoverished areas with bad water.
Householders in the developing world could boil a slice of cactus to release the mucilage and add it to water in need of purification, says Alcantar. “The cactus’s prevalence, affordability and cultural acceptance make it an attractive natural material for water purification technologies.”