Develop a cheap way to kill bacteria in water, and you can provide clean drinking water to millions, maybe billions, of people in the developing world.
Then you can head to gym class, because you're a 14-year-old girl in New Hampshire.
Deepika Kurup's water purification system exposes unclean water, titanium oxide and zinc oxide to sunlight, creating a free radical that kills harmful bacteria.
Kurup's invention just won the Discovery Education 3M Young Scientist Challenge, with an award of $25,000.
See the story at Fast Company.