For travelers in developing countries, exposure to unsafe water can be a big risk. Wouldn't it be great if you could just dip a magic wand into water and purify it? Now, essentially, you can. A handheld device called the SteriPEN, marketed by Maine-based company called Hydro Photon, uses ultraviolet light to eradicate disease-causing microorganisms. The device employs the same purification technology used by bottled-water plants, but it's been miniaturized, so that it weighs just 6.5 ounces (184 grams) and fits into a backpack. Stick it into a liter of stream or pond water for 90 seconds, and voila -- it's safe to drink [source: Stone]. Such portable water purification systems can destroy bacteria, viruses and protozoa, such as giardia and cryptosporidium, which can cause sickness [source: New York Times].
The big market for SteriPENS is backpackers and travelers, but they're also used by the U.S. military. SteriPEN also has donated some of the devices to game wardens who have to work in remote wilderness areas where they don't have access to tap water [source: Stone]. One caveat with ultraviolet purification: Water that's cloudy must be pre-filtered first in order to remove particles that are in suspension [source: Centers for Disease Control and Prevention].