Turns out the nonsensical yuppie idea that bottled water is “cleaner” is actually true, in very very specific circumstances. In areas where it’s hard to find drinkable water, plastic bottles and sunlight can save lives.
SODIS, or solar water disinfection, is a fancy way of saying, "Leave germy water in a plastic bottle out on your hot roof and eventually all the bad stuff will die." It's a simple idea, but remarkably effective at dealing with water contamination. Fast Company reports that it can cut incidence of diarrhea by more than 85 percent, that more than 5 million people in about 30 countries use the technique, and that it’s easy to implement.
SODIS works by exposing contaminated water to the sun's UV rays, destroying the genetic material and cellular structure of viruses, bacteria, and protozoa. PET plastic bottles work best, as they're both durable and allow much of the UV radiation to pass through them. Bottled water is left outside for at least six hours (or 48 hours if it's cloudy), and then stored for future use.
Quick, someone tell the Gates Foundation! Maybe they can use some of their sanitation cash to spread the good word on this one.