The Steripen
This device is made specifically for travelers needing to purify water on the go. It is relatively inexpensive, compared to good water filters and it is compact. It uses ultraviolet rays to kill all bacteria and viruses. I have used it several times and have no complaints. I think it will come in real handy while traveling to our mission churches and eating in Haitian homes.
Let me just add the final story on this steripen. The bulb burnt out after using it less than 10 times. Not a good track record.