A worker washes the exterior of a Portland Loo in Portland, Ore. San Diego installed two of the loos earlier this year. Rick Bowmer/AP hide caption

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A Lebanese woman covers her nose as she walks past piles of garbage on a Beirut street. Hassan Ammar/AP hide caption

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"Parents enroll their kids here because of our child-friendly toilets," says Eunice, the co-founder of a Kenyan school with latrines designed specially for kids. Frederic Courbet/WSUP/Panos hide caption

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Raya might tickle Elmo with toilet paper if he doesn't use it properly. John Barrett/Courtesy of Sesame Workshop hide caption

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More than 170 volunteers in the Brattleboro, Vt., area have contributed urine to the Rich Earth Institute field trials. Mike Earley/Courtesy of Rich Earth Institute hide caption

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Contaminated water can spread diseases like cholera and typhoid. A new project aims to provide water filters in the form of an educational book. Soe Than Win/AFP/Getty Images hide caption

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A makeshift latrine hangs over the water at the edge of Cite de Dieu, a slum in Port-au-Prince, Haiti. John W. Poole / NPR hide caption

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A boy collects water at a new spigot in Shululu, Tajikistan. Before the government built a new water system, villagers were allocated half-hour time slots to collect water from a trickling tap. Jason Beaubien/NPR hide caption

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A young boy plays on a commode during an event for World Toilet Day in New Delhi in November. An estimated 131 million Indian homes don't have a latrine or a clean toilet. Raveendran/AFP/Getty Images hide caption

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Bill Gates, co-founder of the the Bill & Melinda Gates Foundation, checks out a toilet demo at the Reinvent the Toilet Fair in Seattle, Wash. The festival featured prototypes of high-tech toilets developed by researchers around the world. Bill & Melinda Gates Foundation hide caption

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