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Iodine vs ClO2 for long term use (thru-hike)
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Dont Wantto
(longhiker) - F
Iodine vs ClO2 for long term use (thru-hike) on 06/28/2010 20:40:53 MDT Print View

Not really long term but for a 35 day thru-hike of the Colorado Trail. We will not have any other mode of filteration and plan to treat all the water we drink in the backcountry.

We'll be using it pretty much everyday.. so I figure 4 - 5 liters per day per person.. that'd be:

1) 5 of those bottles of Iodine in a month (50 tablets in a bottle)


2) 120 individual ClO2 tablets

I was thinking of going with a mixture of these two to hedge. Please let me know if one / both of these will make my arms fall off or if one is safer than the other etc..

Again, no other mode of filteration and we plan to treat all the water we drink for about 35 days.

Have people on the AT / PCT / CDT relied chemical all the day? How did they turn out?

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Iodine vs ClO2 for long term use (thru-hike) on 06/28/2010 21:45:25 MDT Print View

I used to use Iodine for water treatment about 25 years ago, but I seldom used Iodine pills. Back then, it was easier to get Iodine crystals, and we used a saturated solution of Iodine to measure into our raw water container.

Also, you may find some people are very sensitive to Iodine and some are not. That may have something to do with the thyroid gland. One gal got an Iodine hypersensitivity problem started that way. So, I recommend using the lightest concentration that seems effective. I haven't checked it lately, but the Iodine pills used to have approximately twice the concentration that was necessary to kill giardia in the water.

Also, if you happen to have Iodine-treated water, don't use that on any starchy food (noodles, potatoes, etc.) or else you get a starch reaction and everything turns purple. It actually doesn't hurt anything, but it just looks weird.


Dont Wantto
(longhiker) - F
so nothing concrete about long term effects? on 06/29/2010 14:35:34 MDT Print View

So there isn't some definite answer about long term effects of chlorine or iodine?

About sensitivity, I've certainly used about 50 tablets of iodine over my backpacking trips... but they are usually for a couple of days at a time with a few weeks in between of no iodine use. I guess this means I'm not sensitive / allergic?

It'd be great to know if one of these is not recommended for a thru-hike.. surely all the 1000s of people who've hiked the AT /PCT / CDT must know something about this.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: so nothing concrete about long term effects? on 06/29/2010 15:38:24 MDT Print View

Back in the days when I used Iodine crystals routinely, there was some kind of warning that I had read where Iodine treatment of water was not for long term purposes, but there was never any guidance about what a long term was.

I remember using one bottle of Iodine pills, and I remember that they created a moderately bad taste in the water. Then I discovered about the concentration and that explained a few things. Also, Iodine pills have a limited shelf life once the bottle is opened. They still work after that time period, but they are slower to dissolve. Of course, that is another case for crystals over pills.

For me right now, gravity filtering is the ticket.


Willie Evenstop
(redmonk) - F

Locale: Greater Yellowstone Ecosystem
Iodine vs ClO2 for long term use (thru-hike) on 06/29/2010 16:17:37 MDT Print View

I wouldn't use iodine for long term water treatment. As I read the guidelines, your trip is at the limit of the recommended maximum length of iodine use, but will be at a higher concentration than the maximum recommended.

Recommendations for short-term emergency use of iodine are generally limited to approximately 3 weeks, at concentrations less than 0.5mg/L for treating bacteria/viruses. (1,2,3) Wilderness water treatment would be close to 8-16 mg/L for giardia cysts, well beyond the recommended maximum intake amounts. (4,5)

For reference, 60% of school children in central China developed goiter where the water naturally contains iodine content of 462 [micro]g/L .(6)

1) Water and Sanitation for Health Project. Triocide Questions end Answers. Arlington, VA:U.S. Agency for International Development, 1980.
2) Zoeteman B. The Suitability of Iodine and Iodine Compounds as Disinfectants for Small Water Supplies. Tech Paper No 2. The Hague:World Health Organization International Reference Center for Community Water Supply, 1972.
3) National Academy of Science Safe Drinking Water Committee. The disinfection Of drinking water. In: Drinking Water and Health, Vol 2. Washington, DC:National Academy Press, 1980;5-139.
4) Backer H. Field water disinfection. In: Wilderness Medicine: Management of Wilderness and Environmental Emergencies (Auerbach P, ed). St. Louis, MO:Mosby, 1995;1061-1110.
5) Powers E. Inactivation of Giardia Cysts by Iodine with Special Reference to Globaline: A Review. Tech Rpt Natick/TR-91/022. Natick, MA:U.S. Army Natick Research, Development and Engineering Center, 1991.
6) Mu L, Derun L, Chengui Q, Peiying Z, Qidong Q, Chunde Z, Qingzhen J, Huaixing W, Eastman C, Boyages S, et al. Endemic goitre in central China caused by excessive iodine intake. Lancet i:257-258 (1987).

Edited by redmonk on 06/29/2010 16:34:04 MDT.

Ben Crowell
(bcrowell) - F

Locale: Southern California
Re: Iodine vs ClO2 for long term use (thru-hike) on 06/29/2010 19:08:12 MDT Print View

Excellent info, Cameron -- thanks for posting that!

What is the recommended maximum amount of iodine given in your references 4 and 5? Is that a recommended maximum for water that on is going to drink daily as part of one's household routine, or is it a maximum for some specific time-frame?

Is there any downside (in terms of health) to using ClO2 for a long period?

Longhiker -- I recently mistakenly bought a bunch of ClO2 tabs, not realizing that I already had some in a closet. If you want to buy them from me, send me a PM.