Theresa Dankovich invented germ-killing water filters as a graduate student and co-founded her company Folia Water in 2016 to scale up production. Folia Filters (patent pending) are made of thick paper embedded with silver nanoparticles, which are lethal to microbes. The filters are distributed in Safe Water Books—each book provides a year of safe drinking water for a family. Dankovich’s team has field tested her inexpensive filters with users in South Africa, Ghana, Honduras, Bangladesh, Kenya, and Haiti. “I saw an opportunity to simply listen to the people . . . and to deliver designs that fit with the culture,” she notes.