Whether you’re traveling the world or sitting in your living room, waterborne disease can be an issue. While generally the water in the United States is safe, aside from unexpected, isolated water boil alerts, the water quality in poor or developing nations often pose high risks for illnesses such as Travelers’ Diarrhea, which affects up to half of all international travelers.

Drinking bottled water is usually the most convenient path to ensure your drinking water is safe, but can sometimes be inferior to tap water, more expensive and create huge ecological problems in developing countries that do not recycle the bottles.

Below is a list of techniques for international travelers to ensure safe drinking water without relying on bottled water:

Heat

Boiling water is the most effective way to kill common intestinal pathogens and it is the only easily recognizable way to kill bacteria at a high temperature without using a thermometer.

Filter the water before boiling if the water is visibly dirty and allow sediments and particles to settle after boiling. Then decant the water from the top into another container and let it cool by itself, without adding ice. 

All organisms, except bacterial spores, which are not usually found in water, are killed immediately at a boiling temperature. Boil the water for one minute to ensure it is completely safe, unless you are at a high altitude location, in which case the CDC advises three minutes, because the boiling point decreases with increasing altitude.

Tap water that is too hot to touch can’t be guaranteed to be safe because it is likely at a temperature between 120 degrees Fahrenheit and 140 F. Water should reach at least 150 F to kill pathogens.  

Disinfection tablets

Store-bought iodine and chlorine tablets can be an inexpensive and easy way to kill bacteria and viruses; however they are ineffective against protozoa (one-celled animals such as cryptosporidium that can cause infections in humans.)

• Iodine is more effective than chlorine, but it is not recommended for long-term use, because it has physiologic activity. The World Health Organization recommends limiting the disinfectant to a few weeks of emergency use. Due to the potential effect iodine may have on the fetal thyroid, it is not recommended for persons with unstable thyroid disease, known iodine allergy or pregnancy.
• Chlorine is the most common disinfection method for improving and maintaining microbiologic quality of drinking water. Sodium hypochlorite, common household bleach, is the primary disinfectant promoted by the CDC and WHO Safe Water System for individual household use in the developing world, according to the CDC.

As a last resort, mix two drops of common chlorine bleach in a quart of water. Add a tiny pinch of ascorbic acid (vitamin C, available in powder or crystal form and as an ingredient in most flavored drink mixes) after the required contact time to remove the unpleasant taste.

Potable Aqua, composed of the iodine compound tetraglycine hydroperiodide, is one popular brand of water purification tablets that can be purchased for less than $10.

Ultraviolet (UV) Light

Ultraviolet light kills bacteria, viruses and protozoa, but there is a lack of independent testing data available on specific products, according to the CDC. UV requires effective pre-filtering due to its dependence on the cloudiness of the water, the correct power delivery and correct contact times to achieve maximum pathogen reduction.

UV light products, like the SteriPEN, are portable, effective and easy to use; however they can be pricy, averaging about $90.

Filtration

Filters with the smallest pores, between 0.1–0.4 μm (micrometers), are the most effective for removing cysts and bacteria, but might not adequately remove viruses, which are a major concern in water with high levels of fecal contamination. Because one of the most common illness while traveling is Travelers’ Diarrhea, which often is contracted through the ingestion of Escherichia coli bacteria in food or water contaminated with feces, filtration might not be the best option.

Reverse osmosis filtration removes microbiologic contamination and salt from water. However, because of the cost and slow production of small hand-pump reverse-osmosis units, they are impractical for use by land-based travelers. On the other hand, they are important survival aids for ocean voyagers.

The most effective way to use filtration is to buy a system that combines filtering with chemical purification or filter water before using one of the other techniques.

To research other water filtration techniques, including Sodium Electrolysis, Solar Irradiation and Granular activated carbon, please view the CDC’s Field Techniques for Water Treatment.

Sources:

Centers for Disease Control and Prevention. “Water Disinfection for Travelers,” http://wwwnc.cdc.gov/travel/yellowbook/2010/chapter-2/water-disinfection.aspx ; accessed 11 Nov. 2009.

Independent Traveler. “Drinking Water Safety,” http://www.independenttraveler.com/resources/article.cfm?AID=55&category=5&page=2; accessed 12 Nov. 2009.