Military Canteen Water Purification

Water Purification Tablets are a military necessity, carried by the Soldier in the pocket on the canteen carrier, as a component of an individual first aid kit, or in other gear. Water Purification Tablets are also issued with group first aid kits or packed with medical supplies distributed for military operations or disaster relief.

A bottle of 50 Tablets, Water Purification, Individual, Iodine sits on the open side pocket of a nylon canteen carrier
A bottle of 50 Tablets, Water Purification, Individual, Iodine sits on the open side pocket of a nylon canteen carrier.

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Bottle of 100 Halazone tablets

Military Canteen Water Purification

The first field treatment for water was ancient and primitive: use a cloth to strain out impurities, then boil the water for at least one minute. While this was effective in preventing many water borne diseases, it required troops to concentrate attention on their water for significant time and to expose their position by lighting fires. A better way was urgently needed. Army researchers looked for chemical treatments as a solution.

The purification of drinking water by the use of liquid chlorine was developed in 1910 by Major Carl Rogers Darnell, Professor of Chemistry at the U.S. Army Medical School. He later designed a purification filter for field use in World War I. Around the same period, Major William Lyster used a solution of calcium hypochlorite in a linen bag (Lyster Bag) to treat water. Small vials of chlorine solution were issued to troops, prior to World War II, for water treatment. A cap-full of chlorine bleach, put into a canteen of water, is an emergency method still used when nothing else is available. Older veterans remember standing in line to get bleach from their squad leader.

Chemical treatments for soldiers' canteen water have been continuously studied and improved, resulting in a series of standard treatment chemicals issued to the individual soldier, as well as methods for treatment of group water sources.

Halazone Tablets for Military Canteens

Halazone (4 dichlorosulfamyl benzoic acid) is a white, crystalline powder made from a chlorine compound. It imparts a strong taste and smell of chlorine to the water. Halazone was developed in the early 20th century, and was used during World War I. By 1940, Halazone tablets were available as a conventient and effective water treatment for individual soldiers. Halazone was supplied in small brown glass bottles (packed with K rations and C rations during WW II) and training was provided with proper instructions in their use. Halazone was a major medical item of supply during World War II.

The Halazone tablets were sized so two tablets, dissolved in a full one quart canteen, would disinfect the water.

Halazone was a component of individual and group first aid kits, supplied to U.S. forces until after World War II at which time iodine tablets became the standard for military use. Halazone continued in use through the Vietnam War at least. The shelf life of Halazone is about 2 years from date of manufacture.

MED 3 Catalog Item Numbers for Tablet, Water Purification, Individual, packed in bottles, by quantity:

Tablet Quantity MED 3 Catalog Item Number
100/Bottle 9121805 (former 1K27505)
200/Bottle 9121810 (former 1K27507)

Iodine Tablets for Military Canteens

Halazone, which relies on chlorine reactions, is not fully effective in tropical areas, but iodine-based disinfectants are. Therefore, Halazone was replaced in the U.S. services by Globaline tablets, an iodine compound. Globaline was developed by researchers at Harvard University and has many advantages over the Halazone tablet for water purification. In addition to its effectiveness in hot weather, tests showed that Globaline disintegrated and dissolved in less than one minute while standard Halazone tablets required seven minutes. Overall, Globaline iodine was much more acceptable in use than Halazone.

The iodine-based Globaline was used by American troops for canteen water purification from 1952 until about 1990, and has continued in use even after newer alternatives were developed. However, the military found that Globaline iodine tablets are very limited in use; they do not remove sediments or chemicals, and they are not very efficient against biological contamination. Globaline is not strong enough to kill cysts and viruses. Furthermore, Globaline use is adversely impacted by reduced disinfection efficiency under certain conditions:

  • At low temperature and pH, especially for the enteroviruses.
  • At high pH for certain protozoan cysts such as Giardia and CrvytosDoridium.

Because of such limitations in disinfection effectiveness, military doctrine was changed to require two Globaline tablets per liter of drinking water with a contact time of 35 minutes before human consumption. The use of two tablets contributes significant adverse organoleptic (taste and odor) properties to the treated water. These problems and the potential avoidance of water can be a serious concern where personnel may be required to consume up to 15 liters a day to prevent dehydration (i.e. especially in hot, arid climates).

Globaline was manufactured for the U.S. Army by Van Ben Industries, Long Island, NY, Worthy Chemicals, Inc., Brooklyn NY, and by the Wisconsin Pharmacal Company, Jackson, WI. This NSN was used for the small 50 tablet bottle, for the pocket of a canteen ocver or packed with first aid kits:

  • NSN 6850-00-985-7166 WATER PURIFICATION TABLET, IODINE, 8 MG, 1 BT, 50s. MIL-W-283.

The bottle is sealed with paraffin wax. Traditional guidance has been to check the wax seal on the bottle and make sure the tablets are "steel gray" in color. According to the Defense Supply Center (Richmond, VA), the shelf life of Iodine Tablets is 36 months.

Globaline iodine tablets are available as Potable Aqua for civilian use, available from at the linked page.

Directions and procedures for the utilization of iodine tablets for disinfecting water can be found in TB MED 577 (Sanitary Control and Surveillance of Field Water Supplies) and FM 21-10 (Field Hygiene and Sanitation).

Chlor-Floc Emergency Water Treatment

Chlor-Floc is an emergency disinfectant mixed with a settling aid that helps remove dirt and other suspended particles from water by flocculation and sedimentation. If it is available, it should be used when the water to be treated is cloudy or discolored and the operational situation is such that the treatment bag can remain motionless for the required settling period and can then be filtered.

In the early 1990s, the U.S. Army did a market investigation looking for a new emergency water purification method based on COTS (commercial off-the-shelf) chemical compounds -- coumercially available, non-developmental and able to satisfy the new military requirements. The search resulted in the selection of a tablet called Chlor-Floc. The Chlor-Floc (CF) tablets combine sodium dichloro-isocyanurate, the active ingredient, with proprietary flocculating agents that clarify the treated water by coagulating particles in the water as the water is being disinfected. The heavy coagulated particles settle out, leaving the water above the sediment clear.

When dissolved in water, the active ingredient in Chlor-Floc dissociates to hypochlorous acid and chloride ions depending on the final pH of the water. The tablet also contains a buffering system which buffers the treated waters to a pH that is most optimal to achieve disinfection of the water. Chlor-Floc may provide improved water purification over a broad range of pH and temperature, and may not suffer from interferences by organic chemical demand in field water supplies.

Another tablet called Aquapure (AP), very similar to the CF tablet and containing the same active ingredient, was also evaluated and compared to CF.

After testing, Department of the Army, Office of The Surgeon General approved the use of Chlor-FLoc tablets and all ccmponents of an associated water purification kit as Common Table of Allowance 8-100 medical expendable items. By this action, iodine tablets were replaced by Chlor-Floc Emergency Drinking Water Tablets as the standard, although iodine tablets continue to be used.

Chlor-Floc tablets were manufactured by the Control Chemical Ccmpany in South Africa represented by Deatrick and Associates Inc, Alexandria, VA. Aquapure (AP) tablets were manufactured by the World Resources Company, McLean, VA.

The Chlor-Floc tablets are a component of a kit issued to soldiers containing 30 chlorine flocculating tablets, 3 cloth filter pouches and one plastic water treatment bag, designed to support a three day mission. The kit nust conform to Commercial Item Description A-A-52122, 1993, entitled Kit, Water Purification, Emergency and the tablets to A-A-52119 Tablet, Chlorine, Flocculating, Emergency Water Purification. The kit and its components are:

Item NSN
Chlor-Floc Treatment System (kit) 6850-01-374-9921
Chlor-Floc Tablets (box of 3 packages, 10 tablets each, total 30, 600 mg tablets) 6850-01-352-6129
Chlor-Floc Treatment Bag 6850-01-374-9923
Chlor-Floc Treatment Cloth Filter 6850-01-374-9922

Each Chlor-Floc tablet is designed to leave the water with approximately 1.4 mg/L (ppm) of free available chlorine per liter. The shelf life of Chlor-Floc is 3 years from the date of manufacture.

Directions and procedures for the utilization of Chlor-Floc for disinfecting water can be found in TB MED 577 (Sanitary Control and Surveillance of Field Water Supplies) and FM 21-10 (Field Hygiene and Sanitation).

Chlor-Floc is available from at the linked page.

Individual Water Purifiers (IWP)

While Chlor-Floc and iodine provide workable solutions to the continuing problem of disinfecting drinking water in the field, there may be better solutions offered by COTS (commercial off-the-shelf) products that have emerged in the civilian market. The U.S. military has conducted extensive testing of such products to determine their performance and safety when measured against military-specific requirements. Such tests are ongoing and recommendations are issued on the lowest-risk IWPs to use. Contact the U.S. Army Center for Health Promotion and Preventive Medicine for more information.

See also Field Hydration.

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