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Where did all the water bottles come from? Just a few decades ago, no one carried bottled water around with them, and now it's totally ubiquitous. What changed? Hydration is a real thing in science, but it was also a kind of invention: used by marketers of sports drinks, bottled water companies, and the wellness industry to keep us buying and drinking water for clearer skin, better health, and all sorts of other nebulous benefits. To hear the full episode now, sign up for Slate Plus. Otherwise you'll hear this episode in June when our full season launches. Learn more about your ad choices. Visit megaphone.fm/adchoices