You are ready for your vacation, yet you are still concerned about the quality of drinking water once you reach your destination. 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.
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:
- Beverages, such as tea and coffee, made with boiled water.
- Canned or bottled carbonated beverages, including carbonated bottled water and soft drinks.
- Beer and wine.
Where water might be contaminated, travelers should be take the following additional precautions:
- Ice should be considered contaminated and should not be used in beverages.
- If ice has been in contact with containers used for drinking, thoroughly
clean the containers, preferably with soap and hot water, after the ice has
- It is safer to drink a beverage directly from the can or bottle than from
a questionable container.
- Remember that water on the outside of beverage cans or bottles might be
contaminated. Dry wet cans or bottles before they are opened, and wipe clean
surfaces with which the mouth will have direct contact.
- Avoid brushing your teeth with tap water.
Treatment of Water
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.
- 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. The size of the
microstrainer filter is important as some 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. 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. 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 http://www.NSF.org.
- 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 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. 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.
- 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.
For additional information, please visit the MedicineNet.com Travel Medicine Center.
Portions of the above information was provided with the kind permission of the Centers for Disease Control.
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Last Editorial Review: 5/15/2002