The Miox is the first significant advance in backcountry water purification in years. Dip the unit into a pond to fill its thimble-size reservoir. A built-in table-salt compartment creates a brine solution, which the device—it’s slightly larger than a fat highlighting pen—then zaps with a small electrical charge. Dump the resulting taste-free cocktail into a bottle (up to four liters at a time) to nuke viruses, bacteria, giardia, and cryptosporidia. The device will effectively purify large volumes of water, but it’s not for the parched: It takes 30 minutes to fry giardia and a thirsty four hours to rub out crypto. The Miox may be a cool new toy, but you can trust the science behind it: Many towns and cities purify their municipal drinking water with more or less the same technology.