Three years ago, Priya Sharma was a junior at Lincoln High School in Portland, Oregon, working on a science fair project about water filtration. Today, her solar-powered water purification device is being used in 15 countries, providing clean drinking water to an estimated 50,000 people.

The device, which Sharma designed to be manufactured from locally available materials at a cost of under $30 per unit, uses a combination of UV sterilization and ceramic filtration powered by a small solar panel. Its simplicity and low cost have made it particularly effective in rural communities without access to electrical grids.

Now 19 and studying engineering at MIT, Sharma has partnered with two international NGOs to scale production and distribution. The organizations handle manufacturing and deployment in their respective regions while Sharma continues to refine the design based on field feedback.

"The best part is getting messages from communities where waterborne illness rates have dropped," Sharma said. "That's not my achievement — that's the achievement of every person who helped build and maintain these devices in their communities."