Water Disinfection for Travelers

Travelers and campers are often faced wit questionable drinking water.

There are many techniques available to clean water and work by different ways.

In order to ensure water is drinkable it should be free of: Invasive Bacteria (Salmonella, Shigella and others); Non-invasive Bacteria such as(E. coli) ;Gastrointestinal Viruses ;other foodborne viruses that enter through the gastrointestinal tract including (Polio, Coxsackie, Echo, Hepatitis A) and Parasites such as Amoebae, Giardia, and Cryptosporidia.

Boiling water works  for all organisms

In order to be effective water must achieve a rolling boil for one minute. If above 2, 000 meters (6, 500 feet) the water must be boiled for three minutes in order to be effective.

Boiling is a slow process and is inconvenient. It requires fuel (wood or stove fuel). Wood fires also leave ugly residue

Boiling is not simple or convenient. It is not small and lightweight. However, it is HIGHLY reliable

Portable Water Filters are also used to filter water. The typical pore size of a filter is

0.2 - 0.3 µm.

Infective agents are bigger than this: Giardia Cysts (6.0 µm); Cryptosporidium Cysts (4.0 µm); Bacteria (Diameter1.3 – 3.0 µm) ; and viruses (0.004 – 0.06 µm)

Water filters are bulky and relatively heavy, expensive, and they readily become obstructed

Viruses as well as small bacteria may not be removed. Although some products claim to filter viruses this is hard to believe.

Iodine was found to be fully effective for bacteria, viruses, and Giardia and amoebic cysts .90 seconds is adequate for bacteria and viruses. Some parasites such as cryptosporidium are resisatant to iodine and require longer contact times with iodinated water.Standard contact times (With margin of safety): Warm water (>5°C or 40°F) takes 10 minutes.Cold water (<5°C or 40°F) takes 20 minutes.

There are many manufacturers that use either iodine or chlorine as the disinfecting agent and instructions on contact water will vary from product to product. All are reasonable choices for backpackers providing the manufacturer's instructions are followed.

“Steri-Pen”® is a recently devised ultraviolet water disinfection battery powered device that disinfects 16 oz of water in 45-60 seconds. This is showing promise as it destroys bacteria, viruses and protozoa (including cryptosporidium), which is notoriously hard to destroy.

Whichever method of cleaning water people choose they should be familiar with the limitations of each method and remember not to drink water that hasn' t been cleaned properly