Take a look around. Right this very second there's a water bottle within a 10-foot radius of where you're sitting. How did it get there? A drop of physiological need mixed with an ocean of marketing savvy. Water used to fuel the office water cooler; now it's practically become an anytime-anywhere fashion accessory. Fashionistas — not to mention the mailman, the grocery clerk, your yoga instructor, and the school nurse — can all be seen carrying their bottles and Camelbacks of purified, fortified, and natural spring. And whether you're staying hydrated during a marathon shoe-shopping session or drinking from your home Brita filter, there is no doubt about it: Water, water — it's everywhere. But as with any mainstream megatrend, you have to stop and ask yourself, "What's really going on here?" When water bottles become must-have equipment on a planet that's 70 percent liquid, some of the reasoning is bound to be bunk.