El Tigre Journeys
in the heart of the Amazon

Health and Wellness
for travelers to the Peruvian Amazon
From the CDC Travel Page
Division of Quarantine, National Center for Infectious Diseases
Centers for Disease Control and Prevention, Atlanta, Georgia U.S.A.
updated October 10, 2001

Water Precautions

Contaminated food and drink are common sources for the introduction of infection into the body. Among the more common infections that travelers can acquire from contaminated food and drink are Escherichia coli infections, shigellosis or bacillary dysentery, giardiasis, cryptosporidiosis, and hepatitis A. Other less common infectious disease risks for travelers include typhoid fever and other salmonelloses, cholera, infections caused by rotavirus and Norwalk-like viruses, and a variety of protozoan and helminthic parasites (other than those that cause giardiasis and cryptosporidiosis). Many of the infectious diseases transmitted in food and water can also be acquired directly through the fecal-oral route.

Water
Water that has been adequately chlorinated, using minimum recommended water treatment standards employed in the United States, will afford significant protection against viral and bacterial waterborne diseases. However, chlorine treatment alone, as used in the routine disinfection of water, might not kill some enteric viruses and the parasitic organisms that cause giardiasis, amebiasis, and cryptosporidiosis. In areas where chlorinated tap water is not available or where hygiene and sanitation are poor, travelers should be advised that only the following might be safe to drink:

  1. Beverages, such as tea and coffee, made with boiled water.
  2. Canned or bottled carbonated beverages, including carbonated bottled water and soft drinks.
  3. Beer and wine.
Where water might be contaminated, travelers should be advised that ice should also be considered contaminated and should not be used in beverages. If ice has been in contact with containers used for drinking, travelers should be advised to thoroughly clean the containers, preferably with soap and hot water, after the ice has been discarded.

It is safer to drink a beverage directly from the can or bottle than from a questionable container. However, water on the outside of beverage cans or bottles might be contaminated also. Therefore, travelers should be advised to dry wet cans or bottles before they are opened, and to wipe clean surfaces with which the mouth will have direct contact. Where water might be contaminated, travelers should be advised to avoid brushing their teeth with tap water.

Treatment of water
Travelers should be advised of the following methods for treating water to make it safe for drinking and other purposes.

Boiling is by far the most reliable method to make water of uncertain purity safe for drinking. Water should be brought to a vigorous rolling boil for 1 minute and allowed to cool to room temperature; ice should not be added. This procedure will kill bacterial and parasitic causes of diarrhea at all altitudes and viruses at low altitudes. To kill viruses at altitudes above 2,000 meters (6,562 feet), water should be boiled for 3 minutes or chemical disinfection should be used after the water has boiled for 1 minute. Adding a pinch of salt to each quart or pouring the water several times from one clean container to another will improve the taste.

Chemical disinfection with iodine is an alternative method of water treatment when it is not feasible to boil water. However, this method cannot be relied upon to kill Cryptosporidium unless the water is allowed to sit for 15 hours before it is drunk. Two well-tested methods for disinfection with iodine are the use of tincture of iodine (see table below) and the use of tetraglycine hydroperiodide tablets (for example, Globaline®, Potable-Aqua®, or Coghlan’s®). These tablets are available from pharmacies and sporting goods stores. The manufacturers’ instructions should be followed.

If water is cloudy, the number of tablets used should be doubled; if water is extremely cold (<5° Celsius [<41° Fahrenheit]), an attempt should be made to warm the water, and the recommended contact time should be increased to achieve reliable disinfection. Cloudy water should be strained through a clean cloth into a container to remove any sediment or floating matter, and then the water should be boiled or treated with iodine. Chlorine, in various forms, can also be used for chemical disinfection. However, its germicidal activity varies greatly with the pH, temperature, and organic content of the water to be purified and, therefore, it can produce less consistent levels of disinfection in many types of water. Chemically treated water is intended for short-term use only. If iodine-disinfected water is the only water available, it should be used for only a few weeks.

Portable filters currently on the market will provide various degrees of protection against microbes. Reverse-osmosis filters provide protection against viruses, bacteria, and protozoa, but they are expensive, are larger than most filters used by backpackers, and the small pores on this type of filter are rapidly plugged by muddy or cloudy water. In addition, the membranes in some filters can be damaged by chlorine in water. Microstrainer filters with pore sizes in the 0.1- to 0.3-micrometer range can remove bacteria and protozoa from drinking water, but they do not remove viruses. To kill viruses, travelers using microstrainer filters should be advised to disinfect the water with iodine or chlorine after filtration, as described previously. Filters with iodine-impregnated resins are most effective against bacteria, and the iodine will kill some viruses; however, the contact time with the iodine in the filter is too short to kill the protozoa Cryptosporidium and, in cold water, Giardia. Proper selection, operation, care, and maintenance of water filters is essential to producing safe water. The manufacturers’ instructions should be followed. NSF International, an independent testing company, tests and certifies water filters for their ability to remove protozoa, but not for their ability to remove bacteria or viruses. Few published reports in the scientific literature have evaluated the efficacy of specific brands or models of filters against bacteria and viruses in water. Until such information becomes available, the Centers for Disease Control and Prevention (CDC) cannot identify which specific brands or models of filters are most likely to remove bacteria and viruses. A list of filters that have passed NSF tests for parasite removal can be obtained by calling 1-800-673-8010; by writing to NSF at 789 North Dixboro Road, P.O. Box 130140, Ann Arbor, Michigan 48113-0140; or online at the NSF International Web site.Disclaimer

As a last resort, if no source of safe drinking water is available or can be obtained, tap water that is uncomfortably hot to touch might be safer than cold tap water; however, proper disinfection, filtering, or boiling is still advised.

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