UV light: it might give you cancer, but so too will it save you from intestinal worms and a night of Montezuma's revenge. SteriPen's water purifier for travelers arrives as a pocket-sized, half-pound wand with a 4-pack of AA batteries, and the power to sanitize 3,000 1/2-liter gulps of water on a single UV lamp (each set of batteries is good for about 200 rounds).
The purification process takes 48 seconds for a half liter and 90 seconds for a full liter of water, with steps involved including: 1) Find water. 2) Put it in your bottle. 3) Insert SteriPen at bottle's mouth to seal. 4) Turn bottle upside down and hold. 5) Make the nearest child or nearest adult sucker count to 48 or 90.
Travelers' SteriPens measure 7.6" long x 1.5" wide x 1.5" high. Weight varies from 5.7 ounces with lithium batteries to 7.5 ounces with NiMH batteries.