My wife and I took a year off and travelled through South America(3 months), North Africa(1 month), the Middle East(1month), India(2 months), SE Asia(4 months) and China (1 month) on a tight budget. Our steriPen was probably our best buy overall. We didn't dip any water out of the Ganges or anything, but we never got sick (due to water!) through out. One thing that I think is worth mentioning too, is the fact that you aren't buying bottled water and you aren't throwing away a bunch of plastic bottles. Lastly, we used rechargeable batteries which fit both our camera and the steriPen. (The portable charger was small enough to offset the inconvenience.) In short, not only was it an effective tool, it also is incredibly efficient.