updated 9:52 a.m. ET Aug. 28, 2008

Nothing ruins a good trip like getting sick — and we're not talking about a few extra bathroom stops. Contaminated drinking water is one of the leading sources of health problems for travelers, and can cause anything from mild gastrointestinal distress to serious bacterial diseases.

The most common cause of water-borne illness is bacteria, such as E. coli, cholera and salmonella, but illness can also be caused by protozoa (including giardia and cryptosporidium), viruses (like hepatitis A, polio and rotavirus) and chemical pollutants.

The best way to protect yourself is to avoid local tap water and instead seek out bottled water; when that's not available, boiling tap water generally kills most micro-organisms, and there are a number of good water filters and purification tablets that can easily be stowed in your carry-on. Read on for tips on how to keep yourself safe, healthy and well-hydrated on your next trip.

Know the risks
Mexico is well known for its contaminated water (Montezuma's revenge, anyone?), but according to the Centers for Disease Control and Prevention (CDC), travelers also face high risk in Central America, most of Africa and Asia, and the Middle East. You'll find moderate levels of risk in Eastern Europe, Russia, South Africa, Argentina, Chile and some parts of the Caribbean (including Haiti and the Dominican Republic). Drinking water is generally safest in developed areas of the world like the U.S., Canada, Australia, New Zealand, Northern and Western Europe, many parts of the Caribbean, and Japan.

Keep in mind that water quality may vary depending on where you are in a particular country. For example, in Costa Rica you'll probably find safe tap water at a major city hotel, but you may have to boil water before drinking it if you're staying in a small rural village. If you're not sure, consult a reliable guidebook or ask your   fellow travelers before you leave.

So-called developed countries aren't necessarily risk-free; cryptosporidium outbreaks have appeared in the U.S. Midwest and Northwest, as well as in highly populated cities in Australia. Giardia has been found in the water supply in St. Petersburg, Russia. Check the CDC's Web site to see region-specific health info.

Some cities may advertise their drinking water as being chlorinated, but this doesn't necessarily mean that the water is contaminant-free. Your best approach when faced with potentially unsafe drinking water is avoidance.

What (not) to drink
Bottled water is generally safe, but only in sealed, tamper-proof containers. Ask someone at your hotel to recommend a reliable local brand.

In addition to bottled water, you'll usually be safe drinking tea, coffee, canned soda and juice, beer, wine, and other alcoholic drinks.

Prolonged exposure to higher temperatures will kill many parasites. Drinking from a hot water bottle is slightly safer than drinking untreated cold water.

You don't need to drink contaminated water to be exposed; always consider alternate sources of exposure, like the water you use to brush your teeth, or to wash your contact lenses or dentures. Be sure to use bottled, boiled or purified water for these purposes as well.

Freezing water does not kill bacteria. A margarita on the rocks may sound appealing, but ice cubes present the same problem that tap water does. You can make your own ice if you boil the water first.

Avoid food that may have been rinsed in contaminated water, such as salad and fresh fruit. For more info, see our article on food safety.

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