Entrepreneur Philip Wilson provides clean water to over 300,000 Guatemalan families by doing one thing no one ever thought to do — sell them the very products his own mother’s foundation was previously giving away for free. Because of his radically different thinking, he’s on track to provide access to clean water to 1 million Guatemalans by the year 2020 through his company, Ecofiltro.

But Philip’s idea to charge for a product that was previously free wasn’t always so popular. In fact, when he told his sister — a social worker who had been working on water purification in rural Guatemala for years — she was so upset by his proposal that she stopped talking to him for three months.

“My sister was like, ‘You know, that’s not in the spirit of...