Drinking the tap water in a place you're not familiar with can bring on some pretty nasty business, but carrying a Brita Pitcher around with you isn't really practical. But carrying around the SteriPEN is!
The SteriPEN is a little device that fits in your pocket and can purify a glass of water using just UV rays. Simply stick it in your water, turn it on, and in under a minute it promises to have killed off 99% of bacteria. It even recharges via USB, making it extra convenient. Want one? You can snag it for $120 now.