Jul 31, 2012 at 8:42 pm #1292511
@maiaLocale: Rocky Mountains
Companion forum thread to:Jul 31, 2012 at 11:28 pm #1899078
This article alone is worth the cost (and more) of joining BPL. Keep up the good work!Aug 1, 2012 at 5:47 am #1899110
Roger, et al, It is apparent that you missed some of the finer points of microbiology but the article is more than sufficient for comparing relative drinking water contaminants.
Getting back to sizes of microbes, this has a rather wider variance than you guys intimate. When a bacterium divides, it becomes difficult to determine the size of the daughters. All that is really required are the mechanical necessities for life. You can easily see that a 1/10th size reduction for one daughter is possible, as you mention, but often enough the difference can be greater. Even an absolute filter can let these small daughter cells through. While I have used filters, I do not trust them for this reason. Especially where I will be drinking water several hours after filtering, the cells get a chance to grow after dividing. Amoeba can often slip through pores far smaller than their actual size. I would point out that they have no structure in the cell, hence act almost like a thick fluid. Again, this can take time, but the high preponderance of gravity filters used for overnight filtering can allow a couple amoeba to flow through. On the theory side, this could show up as amoebic dysentery.
Filters are generally statistical in nature. Only the absolute number can be relied upon for filtration and sometimes, even this can fail. Filter fibers are generally laid down in a relatively disorganized state. Absolute filters have set pore sizes. The difference is the cost. Coffee filters, biodiesel filters, or even a cotton ball in a tube are all statistical in operation. Most backpacking filters are better, but still lack the filtration of a good absolute filter.
The overall assumption is that the person using any methode of cleaning water for drinking is healthy and in a "normal" state. Note that for any person, an immune compromised person especially, the active infection can be caused, in all cases, by a single active bacteria, protist or virus. It is statistical. A rather facetious example is the 99.9% safety. You can interpret this to mean 1 person in a thousand will get hammered. Just because one person still gets sick does NOT mean the cleaning method is at fault. This is a rather obscure point that most people miss. As you point out, a difficult thing to trace since it can also be caused by other problems: sanitary conditions, rain dripping off a tree and into your cup, etc.
I am glad you guys pointed out that chemical treatments all qualify as pesticides. Worse, they are generally toxic to people. Which is worse? The disease or the cure? Overdosing water with a large amount of tannic acid in it with chlorine dioxide can give you toxic disorders. Slight overdosing would work better by decreasing this risk, but, also increase the risk from some pathogens. A difficult call in the field, but overdosing with chemicals to improve the efficacy is not always a good solution. If you are out for a long time, alternating methods and chemical types will help reduce toxicity.
Anyway, you make the point that for a normal person, none of this is a problem. I certainly agree. But, every time I slurp up from a clear mountain stream, I cross my fingers… Yes, in most cases of drinking water from these sources, I know my body will handle it.Aug 1, 2012 at 5:52 am #1899111
Glad to see BPL readressing the classic topics.Aug 1, 2012 at 6:59 am #1899126
I'm now depressed : )
There is no certain solution
Either it's hopeless and I just shouldn't be drinking water that's not from my tap,
or I should just forget about it and not bother treating the water
Except, the same uncertainty applies to my tap water, so I shouldn't drink it eitherAug 1, 2012 at 8:13 am #1899148
Hell, Jerry, just dilute the water with ethanol…you won't be able to tell which is making you sick the next day. And certainly not depressed about it. Hay hay…:)Aug 1, 2012 at 8:27 am #1899159
Doesn't ethanol kill "bugs and wogs"?Aug 1, 2012 at 1:11 pm #1899271
@mkeilLocale: Surf City
I have often posted over the years that I use granulated pool chlorine to treat my clean-up kitchen water when backpacking. I wash my dishes in unfiltered water treated with a high concentration of this version of chlorine. I wash my hands in it as well after using the cathole and after a long day on the trail. I add a small amount of dish soap to it when actually washing cooking tools. Does anyone have some comments on the efficacy of this method of treating water (not for drinking, mind you)?Aug 1, 2012 at 1:49 pm #1899284
> Washing my hands after going to the toilet is far, far more important.
Great write up. (And I haven't even read it all yet.)Aug 1, 2012 at 3:41 pm #1899317
Excellent review. I am looking forward to part 3.
Under Dribbles & Drops the calculation I believe is incorrect; 0.1cc in 1,000cc is 0.01% not 0.1% so it becomes 99.99% – big improvement.Aug 1, 2012 at 4:32 pm #1899337
Thanks for the great article.
One source that has helped me decide which water to treat, which method to use, and how long to wait is the EPA Guide Standard and Protocol for Testing Microbiological Water Purifiers.
In particular, Appendix A "Summary for Basis of Standards and Test Water Parameters" has lots of good information. Here’s my translation:
Regarding the 6 log reduction in bacteria:
1. Studies show that raw sewage can contain 10 billion coliform bacteria per liter.
2. Polluted streams can contain 1 million coliform bacteria per liter.
3. Adding a liter of raw sewage to a small (12’ diameter x 3’ deep) backyard swimming pool yields concentrations found in polluted streams.
4. After treatment, a liter of the polluted water should have no more than 1 bacterium.
Regarding the 4 log reduction in viruses:
1. In the United States concentrations of enteric viruses are estimated from 100 to 10,000 per liter in raw sewage.
2. It is estimated that natural waters contaminated with raw sewage may contain from 10 to 100 enteric viruses per liter.
3. Adding a liter of raw sewage to 100 liters of water yields virus concentrations found in polluted streams.
4. After treatment, a liter of the polluted water should have less than one virus (none).
Regarding the 3 log reduction in cysts:
1. Cyst reduction standards are based on Giardia only and some educated assumptions.
2. “Unpublished data” indicate very low levels of cysts in natural waters from less than 1 per liter to less than 10 per liter.
3. After treatment, a liter of polluted water should have less than one cyst (none).
Regarding test waters:
1. The general test water (#1) and the stress test waters (#2-5) are all doped with the same concentrations of bacteria, virus and cysts.
2. General test waters are 68(+/-) degrees Fahrenheit. Stress test waters are 39(+/-) degrees Fahrenheit.
3. Other differences between general test water (#1) and the stress test waters (#2-5) are pH, turbidity, total dissolved solids, and total organic carbon.
4. (Bacteria, virus and cyst reduction is more successful in the general test waters.)
Here’s a link to the EPA protocol
I'd guess that contamination levels in most back country water doesn't come close to the EPA test protocol levels.Aug 4, 2012 at 4:36 pm #1900192
@ouzelLocale: Pacific Northwest/Sierra
I look forward to Part 3. The real world is where the action is at.
Thank you Roger, Will, and Rick for taking the time and effort to do this series.Aug 5, 2012 at 2:15 am #1900310
Roger et al. —
If space permits in Part 3, hope you can cover how much Jack Daniels is needed to take care of all the bugs in a liter of typical backcountry water.
A ratio of 2 to 1, Jack to water? Or something a little (or a lot) stiffer?
Thanks. Great series of articles!Aug 6, 2012 at 1:55 pm #1900662
A very thorough, informative series Roger. Looking forward to part 3.Aug 23, 2012 at 10:50 am #1905306
Alan Van DrieMember
Great article, but here is small correction to your math….
0.1cc out of 1000cc (1L) is 0.01% not 0.1%. So thats 4 nines dilution not 3Sep 12, 2012 at 1:29 am #1911498
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
Just back from 2 months walking in Europe – hence delay in replying.
> It is apparent that you missed some of the finer points of microbiology
Well, glossed over, anyhow.
> Even an absolute filter can let these small daughter cells through. While I have
> used filters, I do not trust them for this reason. Especially where I will be
> drinking water several hours after filtering, the cells get a chance to grow
> after dividing.
Hum … good point! Thank you.
I switched to a Steripen some years ago. However, by now I suspect both Sue and I have built up some inate resistance. (Especially to European cows…)
CheersSep 12, 2012 at 3:08 am #1911501
Roger, Wow, walking in Europe twice now. You lucky SOB! Hope you had fun! You were missed.
Anyway, as I mentioned, cells do not devide evenly. They are also vulnerable to being killed by chemicals at that point, ie, they have incomplete cell walls. They are also vulnerable to your bodies digestive process, a form of immunity if you want to include it as such.
Yeah, the Steripens are pretty good. UV is an excellent disrupter of cellular DNA. I lost mine last year on a steep and rugged downhill. I got another, but the lamp blew. I have a note into them about the cost of replacement.Sep 12, 2012 at 7:44 am #1911544
Roger seems to be in a pattern of spending our summer in the Northern hemisphere and our winter in the Southern hemisphere
Nice Roger!Sep 12, 2012 at 1:11 pm #1911654
Jerry, Yeah, I could only wish I culd trapse all over the world…Sep 12, 2012 at 3:49 pm #1911704
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
> Wow, walking in Europe twice now.
errr… seven times.
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