Water Treatment on Wilderness trips

Proper sanitation and water treatment are important steps in preventing disease from being trasnmitted on backpack trips. There are several methods for treating water, and one that is very effective is use of Iodine, either in tincture or dilute form. Many of our leaders and trip members have used the 4% Iodine tincture because it is lightweight, 100% effective, and easily transported. While this 4% tincture used to be handed out at the start of trips, it is no longer part of the standard commissary equipment. Another form of iodine is the commercially-available product "Polar Pure," which dissolves a small amount of iodine from crystals, and the dilute solution is mixed with water for treatment. What each person does with their personal water is of course their own decision.

All food prepared for group consumption on our trips is made with water that has either been heated to sufficient level to kill cysts, bacteria, and any other organisms, or has been filtered through pumps or gravity-fed micro-porous material, or has been chemically-treated in some manner. Whenever possible, extra boiled or filtered water is reserved at night time for use with the morning's meal. This helps keep the faint taste of Iodine out of milk, for example.

Some people dislike the taste of water treated with Iodine. A simple solution is to use less, and let the water treat for a longer period. Another quite efective and simple way to remove the taste of Iodine is to sprinkle a pinch of lemonaid mix into a bottle of treated water. The ascorbic acid in the lemonaid combines with the iodine to make iodide, which is salty but so faint and dilute you can't taste it. Iodine tincture must never be added to water that already contains lemonaid or any other additive, or it will be rendered ineffective.

Giardia Cysts, Parasites, Bacteria, and Virus Disinfection

Following are directions for the proper use of 4% Iodine tincture.

The rate at which micro-organisms are destroyed is dependent upon the Iodine concentration, the contact time, and the water temperature.

One fourth the standard concentration needs four times the contact time.

Cloudy, heavily contaminated water needs double the Iodine concentration

TimeWater Temperature
4 drops solution / quart10 min.56 F (Sierra stream water)
4 drops solution / quart30 min.34 F (Glacial melt)
2 drops solution / quart20 min.56 F (Sierra stream water)
2 drops solution / quart60 min.34 F (Glacial melt)
4 drops solution / gal.8 hrs.56 F (Sierra stream water)

IODINE TOXICITY: The rare person who is allergic to iodine must not use iodine for water disinfection. Persons with known thyroid dysfunction should determine how they react to water containing iodine at home before using iodine for water disinfection while traveling.


Hot water (140 F) will destroy Giardia in two or three minutes! For any other micro-organism, water is safe to drink by the time is is brought to a boil at 14,000 feet (186 F). Time and temperature are adequate to kill all disease producing micro-organisms.

An excellent paper on the effectiveness of iodine and other forms of water treatment can be found here in a paper by Dr. Howard Backer.