Personal information: I hike almost exclsively in the desert and mountain SW. I don't carry a stove, so I cook over a fire every (nearly every) night. I don't chemically treat my cooking water (just boil it). I boil an extra pot of water before putting the fire out and let it cool for morning water. My water preferencess are:

1: Untreated water from a good source. (happens at least half the time)
2: Boiled water for cooking and, left to cool, for drinking.
3: Treated water. Previously filtered, but I'm going to try the ClO2 tabs.

Even though I'm going to try it - I don't like the IDEA of chemical treatment and would therefor like to use the minimum dose required to do the job. Now, on to my questions:

It's my understanding that a good way to think about the effectiveness of chemical treatments is to use the formula: EFFECTIVENESS IN KILLING PATHOGENS = AMOUNT OF CHEMICAL USED x (multiplied by) THE AMOUNT OF TIME THE CHEMICAL IS LEFT TO WORK. Please, and I know you will, correct me if I have been misinformed.

Obviously, the amount of chemical used must meet some minimum standard of effectiveness. But, my guess is that the minimum amount would be alot less than the recommended dose if it were left for significantly longer than the recommended time of 1/2 hour or even 4 hours - like overnight.

Also, Related Question: From reading this forum it seems that the tabs have 3 times as much ClO2 as AM liquid (per recommended dose). So, given the discrepency in the dosages of AM liquid and the ClO2 tabs, shouldn't the tabs be able to treat more water?

O.K. - I know that the quality of the water will have alot to say about how long and how much chemical is used. But, given some good judgement, shouldn't we be able to use less chemicals?

rionada

Wow, that's a load o' questions.

I'll caution that there likely isn't a direct proportionality at work here, e.g., an infinite amount of chemical won't kill everything instantaneously and an infinitesimally small dose won't kill anything, no matter how long you let it work.

Somewhere between these extremes there certainly must be a balance (ratio) between dose and contact time, but since every container of water is unique that ratio must necessarily differ each time. Cysts are the hardest to kill and most likely to escape a low dosage unscathed. Bacteria and viruses, not so much.

In short, I try to follow the treatment's guidelines while also prefiltering debris and dirt. I've never followed a four-hour treatment period, although sometimes it occurs overnight anyway. And I always try to help dissipate any residual chlorine odor by aerating the water. If the source water was quite clear, I might shorten how long I wait but I don't fiddle much with the dose itself. I simply can't know when I've reached non-lethal concentrations.

The way I go about it is to use the manufacturer's instructions; I figure they don't want to get sued for overdosing their customers, or for providing a recipe that makes the chemical so dilluted that it won't do its job. Still, like you I'm wary of exposing myself to any more chems than I need. I get around it by switching brands/chemical type each trip (might help a little?) and by packing my heavy filter as a shared item when there are enough people in the group to justify it. I also boil most of my water during meals instead of using pills.

I'm sure there is a tolerance within which we could use less or more chemical volume and get good results. I'm not sure I'd want to personally explore that, though. :\

The time needed depends on the temperature of the water. I immediately put the chlorine tab in my water and then set it in the sun to warm. I do about the same as you do, except about 80% of the time I deem my water source as suitable.

It is all a matter of reducing risk, not eliminating it. I would rather be picky about my water sources than just get water anywhere and treat it.

Municipal water is often chlorinated, but then it is tested for chlorine by-products. My understanding is that it is not the chlorine per-se but the by-products that are the nasties. I assume that the makers of the chlorine tabs have run tests for by-products.

I think chlorine tabs make the water taste very flat (alkaline??) even though I do not taste or small any chlorine.

Almost every "reliable source" is chemically treated.

I live in the SE region where humidity is often higher than the temp, which hovers around the mid 90 mark. I can not carry enough "reliable source" or boiled water to fill my needs, which git to 1 gal or more per day.

I have a co-worker that just spent a week in the hospital and another month recovering due to a cracked filter. He lost 40 pounds during that episode and stayed on IV meds/hydration most of a month. He has decided he has no opposition to chemical treatment any more.

Chemical treatment is still the easiest, most portable and cheapest way to go. chemical treatment also allows one to purge the container, inside and out, to avoid cross contamination. Boiled or filtered water in a contaminated container is contaminated water.

KYratshooter,

What did your buddy get? Or did he get everything?

rionada

There are several different pathogens possible in water, and the chemistry is not the same for all of them.

In a loose way, the "formula" you give provides some sense of what is involved, but it is oversimplified. Pushing hard on oversimplifications may not be in your best interest.

Killing pathogens in like a chemical reaction. At first, not much happens. Then the killing reaction sets in and there is a nonlinear decline (not strictly linearly proportional to time) in the concentration of pathogen A (the most easily killed) and after a while, the killing reaction ceases because either all/almost all of the pathogen A are killed, or the concentration of active purification chemical has reached equilibrium with the pathogen concentration - possibly from inadequate initial concentration of the killing chemical.

In the meantime, pathogen B is finally begun to be killed, and the concentration of pathogen B falls nonlinearly with time.... Fill in the story from pathogen A.

Then repeat the story for all of the pathogens C, D .. present.

Some of the pathogens are very resistant to being killed, to different degrees, with different chemicals. For complete safety, one is wise to treat for the worst possible case.

If you are somehow convinced that YOUR water source is free of the worst possible case, you can resort to lesser chemistry doses and "risk it".

As has been noted elsewhere in this thread, in civilized countries, almost all city supplied water is chemically treated. Periodically there are breakdowns in the water supply system, and residents are advised to boil their water.

Maybe you are a "boiler" who lives among pretty pure water and abundant fuel. That is nice, but most of us aren't so fortunate.

There are much better explanations of chemical treatment of water around than the version I gave, and I encourage you to find and study some of them.

Thanks,

I do backpack where there is generally abundant fuel and mostly good water sources. And I do boil for cooking and for morning water. But, sometimes, to be on the safer side I do treat or filter water.

You all have me mostly convinced to go with the recommended dosage.

I still don't get how the ClO2 tablets can be 3 times the dosage of AquaMira liquid (using the same chemical for the same volume of water) and no one will consider treating more water than recommended with the tablets. But, hey, that's just me.

I will probably try it. (I'm thinking one tablet per two liters of water instead of one liter). It's likely that nothing will happen to me. I realize that it won't prove anything since there are so many variables in water treatment. But, I'll let you know how it goes anyway - especially if it it doesn't go well (those stories are always more interesting anyway!?

rionada

How bad are the chemical treatments for your health? Could one of those home Brita or Pur filters remove everything after your tabs kill all the baddies? It says on the filter package that it filters out chlorine and the like.