In the latest What If? by xkcd, a cash-strapped reader asks “what’s the best way to use my free faucet to generate electricity?” Author Randall Munroe discovers that there are far too many roadblocks standing between a homemade hydroelectric bathtub dam and profitability, ultimately suggested the reader go another route altogether.
Single servings of bottled water sells for a dollar or two per half-liter. A lot of bottled water comes from municipal sources—that is, it’s tap water. Bottled water isn’t necessarily about the water; often, people are paying for convenience or because there’s an issue with their water supply. Whatever the reason, however, there’s no reason to let Coca Cola keep all the profits. If you bottled the water from your bathtub faucet and managed to sell each bottle for $1.50, you’d make $72 per minute—$38 million every year.