The Problems of Iodine Tablets for Water Purification

Iodine tablets– One tablet added to a quart releases 8 ppm (parts per million) of iodine.  Two tablets are used for turbid water.  Wait 15 minutes after adding tablets, 30 minutes if the water is cold.  The shelf life of the tablets is 3-5 years.  Deterioration is evidenced by a change in the tablet color; metallic gray is acceptable, light yellow double the dose, and reddish brown discard.  The formation of a precipitate is acceptable.  If there is starch in the water from potatoes, corn or rice the water will turn a blue color.  The blue colored water is harmless and is acceptable to drink.  Iodine tablets are not effective against Cryptosporidium and according to some experts ineffective against Guardia. The iodine tablets leave a strong taste in the water.

Carrying iodine for water purification is a lightweight solution for those in temporary need of clean drinking water.  Kits are available in camping stores that include an iodine pill and a second flavored pill (vitamin C or ascorbic acid) that will remove the iodine taste from the water after it has been disinfected.  The addition of vitamin C, in the form of a pill or in flavored drink powders, precipitates much of the iodine out of solution.  It should not be added until the iodine has had sufficient time to work. This means a minimum of 30 minutes in clear, warm water, but is considerably longer if the water is turbid or cold.

The same general factors apply if you use the crystalline Iodine, except that the shelf life is indefinite as long as it is kept in the crystalline form.

See also  The Doulton Travel Filter, a Solution to Water Problems When Traveling

Warning – Pregnant or nursing women or persons with thyroid problems should not drink water disinfected with Iodine.

I personally do not use iodine or chlorine except in an emergency, today there are much better choices available.  I will cover some of these options in future posts.




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10 thoughts on “The Problems of Iodine Tablets for Water Purification”

    1. Yes, remember putting tabs in the water buffalo. It was better than getting water-borne diseases causing things like vomiting and diarrhea and more.

  1. If iodine is “not effective against Cryptosporidium and according to some experts ineffective against Guardia” – what’s it good for? I mean, why bother.

    1. RationalPrepper

      Sandy it IS effective against Guardia. –iodine crystals is one of the best methods of purifying water for drinking.

      ADMIN: Edited to remove insulting language. Make your point, disagree, but name calling? That belongs on a teen prepper blog, not here. As well, this link may be helpful,

      Or this one,

      Both explain why iodine is NOT the best method for purifying water. Sounds like maybe you need to do some further research.

      1. Thank you. Thank you for the sites as well. Crypto and Guardia are prevalent here. Will stop searching for iodine tabs—————–OR are they still needed for other nasties? OR WILL boiling 1 minute kill them all as well?

  2. Iodine is used to treat as a clinical treatment for people who have contracted Guardia. This is what led the man who created Polarpur. He read an article about a couple that had been lost and then rescued. Both had contracted Guardia.

  3. In 1967, I drank gallons of rice paddy water using nothing but two tablets of military iodine water purification tablets. I carried and drank at least 4 quarts a day.
    Yes I knew that the family and the ox all went in the rice paddy by the hutch all went in it close to the house and assumed where ever they were working and tried not to fill up near there.
    I never came down with anything. Just a air mobile, air assault grunt 1/8th Cavalry 1st plt. weapons sqd.

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