Take, for example, Epic OneWater Brew: a Kölsch-style ale made from purified shower, laundry and sink water. It's the brainchild of Epic Cleantec, a San Francisco-based water reuse technology company born from the Bill and Melinda Gates Foundation's "Reinvent the Toilet Challenge." The company primarily creates wastewater reuse and treatment systems, not beer. Epic Cleantec can't sell its beer, made in partnership with Devil's Canyon Brewing Company, due to strict federal and state laws. But it can give the ale away for free to spread awareness and "showcase the untapped potential of water reuse," Aaron Tartakovsky, the company's CEO, tells CNBC Make It.

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Persons: Melinda Gates, — Ilan Levy, Oded Halperin, Igor, Aaron Tartakovsky —, Aaron Tartakovsky Organizations: Gates Foundation, Devil's, Brewing Company, CNBC Locations: States, San Francisco