Sometimes an item comes along that elegantly and completely solves a traveler's problem, rendering everything else a clumsy alternative. The problem? Local water that you can't drink without getting sick, but plastic water bottle alternatives that are expensive, wasteful, and an environmental nightmare.
Enter the Steripen. Yeah, you can buy some kind of pump with filters you need to replace or a water bottle where you suck through a charcoal mechanism, but overall they're a pain and they take up too much room. This travel SteriPEN, in contrast, is compact and is a technological wonder. You just turn it on, stick it in water, and a minute later the possibly scary liquid in front of you is water you can drink without worry.
I just used one for the past two weeks in Guatemala and not only did this keep me from buying and wasting a big pile of plastic that would spoil the countryside, but it kept me and my family healthy too. Not even the slightest case of the runs. The batteries I had in there didn't run out, but if you are on some kind of backwoods expedition or on extended travels, you can buy a cool solar charger accessory that will (slowly) recharge standard re-useable batteries.
The drawbacks? Well, this breakthrough doesn't come cheap. I could easily argue that it will pay for itself financially over a year and the psychic baggage you drop is worth something, but the upfront investment is around $130 without the charger, which is another $50. Plus the travel SteriPEN water purifier won't fit into the nozzle of a regular commercial bottled water container or a the cool Sigg bottles, so if you are carrying one of those you'll have to borrow a pitcher or a Nalgene wide-mouth bottle for the purifying stage.
Small prices to pay for saving the world if you ask me, so follow this link and do a search at REI.com or buy it here directly from Amazon.