A: My guess is you'll find plenty of bottled water, which means your filter system won't be maxed out every day. Still, as you note, a good, durable filter than can be easily field-maintained is advisable. One choice would be the MSR MiniWorks EX ($80; www.msrcorp.com), a very tough filter that has an easily replaceable ceramic cartridge ($38). It wouldn't be too onerous to pack two of them along, plus a maintenance kit ($12). Katadyn's Pocket Filter is another rugged, long-lasting filter that's easy to maintain on the road. It's a $200 item, however, which may be a factor (www.katadyn.com). A cheaper yet no less rugged and worthy alternative is the Katadyn Hiker ($60), which has an easy-to-use pump mechanism for quick on-the-hoof filtration.

Of course, you also have to deal with filter-proof organisms such as viruses. For that you need a purifying solution, such as MSR's SweetWater Purifier Solution ($9 per bottle). You add it to filtered water, let it stand for five minutes, then drink.

As a backup, there's old-fashioned Potable Aqua ($6; www.potableaqua.com), an iodine-based tablet that kills just about everything in the water from giardia on down the food chain. It doesn't taste great, but if you're in a hurry then it works fine. And no, you can't possibly drink enough of it for the iodine to pose the remotest danger.

Bon voyage!

Check out Outside Online's Filtration & Purification Buying Guide for more aqua-cleansing options.