Drinking Water for Hiking: Myths and Facts

[Bob Gross]

It is also interesting to note that the Hetch Hetchy aqueduct system is having cross-connections added, just of late. This is a security measure intended to maintain some degree of water delivery even if terrorists manage to knock out part of the pipes. It is interesting in that this current project cost $billions. I've been watching its progress for the last couple of years.

I'm not sure whether that will make the water better or worse.

–B.G.–

[Buck Nelson]

Greg: this part I agree with "So, is all water clean? Nope.
Is it as bad as industry has lead us to believe? Not at all."

I don't agree with the gist of the rest of your post. Decades ago, no one I know was worried about Lyme Disease, either. Yet thousands of people suffer from Lyme Disease now: http://www.cdc.gov/ncidod/dvbid/lyme/ld_Incidence.htm

Decades ago, I think people didn't talk about Giardia. But now "Giardiasis is the most commonly reported pathogenic protozoan disease in the United States. Travelers are the largest risk group for giardiasis infection, especially those who travel to the developing world. Giardiasis is prevalent among hikers and campers…The CDC estimates that there are upwards of 2.5 million cases annually. [note: this latter apparently refers to the whole US population."] http://www.giardiasis.org/Prevalence.aspx Giardia is not some imaginary boogie man.

Now, if people do in fact get Giardia in the backcountry, and they do, for sure, (3 times for myself alone) they are getting it by ingesting cysts. It's been proven that that can happen with drinking water or by poor hygiene. No one has ever determined the break-down of the actual percentages on the sources/causes, it's guesswork.

The Myth Buster paper makes a lot of good points, but it's not a scientific paper (neither is this post, of course.) He does a lot of data mining. I could easily write a similar sourced paper spun the other way and backed up with lots of sad stories of sick hikers with confirmed cases of Giardia.

Bottom line, the risks of Giardia are often overblown. But Giardia is undoubtedly common, and people can and do get it from drinking water. Whether or not the risk is worth treating water and practicing good hygiene is an individual call.

[Greg Mihalik]

"Now, if people do in fact get Giardia in the backcountry, and they do, for sure, (3 times for myself alone) they are getting it by ingesting cysts."

You tested positive for giardia? Three times?

[Jeff Hollis]

One article I read many years ago stated that our ancestors were exposed to Giardia but had a tolerance for it and that modern water purification has eroded our tolerance. I have never seen it repeated in any article so does anybody know if there is any truth to it?

Jeff

[Rick Dreher]

Neglected to introject my Rocky & Bullwinkle reference in a faux Russian accent–my bad.

Cheers,

Bori…er…Rick

[Rick Dreher]

Hi Jeff,

We refer to this as the Ray Jardine water's-too-darn-clean-for-our-own-good theory. WRT Giardia some portion of the population can injest it and remain asymptomatic, some portion will get sick but spontaneously recover and some will remain chronically ill without treatment. For the immunocompromised, Giardia and Crypto can be serious indeed, perhaps fatal.

Cheers,

Rick

[Buck Nelson]

I was diagnosed by physicians three times. Once tested, confirmed by the lab. All three times very sick for extended periods with unique symptoms which quickly cleared when treated.

It seems illogical to me to assume it wasn't from drinking water when the source is unknown, and people sometimes do get Giardia from drinking water in "civilization." In 20 some years straight (after my first two bouts) I was careful about treating water and I never got Giardia. The trip where I was the MOST careful about hygiene, and finally stopped treating all water, I got Giardia in a few weeks. Not slam dunk, but powerful enough evidence to me to return to treating drinking water.

[Bob Gross]

It would be very interesting if we could find out the one most common factor why some people get the illness, and others don't.

As an example, some people might have a pH in their gut that fosters giardia blooming. The next person might have a pH that kills the giardia.

This thought has been raised over and over again for decades, and I don't think that there is any consistent answer. For the example, if we simply knew that pH was the factor, we could consume something to change the pH radically, and that might ward off the giardia symptoms.

–B.G.–

[Paul McLaughlin]

I have been diagnosed with giariasis once – though the tests were not positive and the doctor I dealt with said they are often not positive even for people who are infected – and I'm pretty sure I had it another time, since the symptoms were identical to the time I was diagnosed. Neither from Sierra water, by the way. It's not something I'd care to have again, and I found the cure nearly as unpleasant as the disease. So I'm pretty careful about my water, but I don't treat it all the time. I do when I am in high use areas, but often don't when I am well off trail. Or when I am standing at the spring or where the snowmelt runs out of the snowbank.

As for water consumption, I work as a contractor/carpenter, and am often outdoors working hard in 90 degree plus weather. I can definitely see the difference in the color of my urine when I drink less, and I can feel it when I drink less. I find that I need a least a gallon of water to get me through the workday in those conditions – that's after I have maybe 12 oz or so in the morning before going to work, and then I'll drink probably another quart after work, so altogether it's really almost a gallon and a half, and sometimes more than that. I know I am not drinking too much because even with all that I may not have to urinate all day. It's kind of an extreme situation, but not more so than hiking all day in hot weather. And I do find that in situations like that I definitely need to drink before I am thirsty or I'll have a hard time catching up. And If I get behind on my water I can feel the difference in energy and at the end of the day I will have more muscle soreness. I think in normal circumstances drinking when you are thirsty will do just fine, but in extreme circumstances, like working hard in hot weather, or backpacking at high altitude in warm, dry weather my thirst at least does not keep up.

The other end of the spectrum is working in the winter – which for me isn't very cold weather, but temperatures in the 40's mean I can work all day and hardly ever sweat, and then I am comfortable with maybe a liter of water or less all day. So how much I perspire is the big factor for me. Cold and damp – I don't need much water even when working hard. Hot and dry and sweaty – I need lots of water.
I have a friend who really sweats a lot – if we go on a hike on a warm day where I end up with my shirt damp here and there, his is so wet he can wring it out. And he's in better shape than I am if anything – he runs regularly. And it's not as if he really runs hotter than I do – He's cold when I'm cold. He just sweats a lot more. So he has to drink a lot more water than I do to stay hydrated.

What it comes down to is that one person's water needs are not the same as another's,and what you need in one set of conditions is not what you need in another set of conditions, and the only way to know what you need for particular conditions is to have experience in those conditions yourself. And If you are going into conditions you don't have experience in, be conservative until you know what works for you.

By the way – I had a kidney stone years ago and the urologist told me, after analyzing the stone and doing a test where they save all your urine for a whole day and analyze that, that my problem was I just didn't drink enough water. Since then I am more careful about getting enough – kidney stones are no fun!

[Gregory Petliski]

I treat ALL water in the backcountry. Being miles from help, and alone, is no place to be getting Giardia or other dysentary type illnesses.

[Ben Crowell]

"I treat ALL water in the backcountry. Being miles from help, and alone, is no place to be getting Giardia or other dysentary type illnesses."
Giardia takes several weeks to incubate, so unless you're out for several weeks, you're not going to come down with it while you're out hiking. Even if you are out on a long through-hike, the article also gives evidence that through-hikers who use water treatment don't get less diarrhea than those who don't.

[Rick Dreher]

Per the CDC the average time from Giardia exposure to symptoms is seven days but can take as long as two weeks.

http://www.cdc.gov/parasites/giardia/gen_info/faqs.html

Of course, Giardia is but one of many waterborne diseases present in the mountains. The whole topic of water and water treatment is one of risk management, not risk elimination–which is impossible.

Cheers,

Rick

[John S.]

Lots of people are out longer than 7 days, the average time to symptomatic Giardiasis.

[Ben Crowell]

"Lots of people are out longer than 7 days, the average time to symptomatic Giardiasis."
Yes, that's why I also pointed out the evidence from data on through-hikers that water treatment doesn't reduce the incidence of diarrhea.

[Buck Nelson]

First of all, I want to applaud the general sensible level of discussion.

Even if you are out on a long through-hike, the article also gives evidence that through-hikers who use water treatment don't get less diarrhea than those who don't.

I think that can be very misleading. Who is the most likely to treat their water? People who are most susceptible to stomach ailments. I will now always treat my water (again.) But, as someone susceptible to Giardia, I'll still have a higher risk of getting sick than the significant part of the population that never gets sick, hundreds of thousands of which carry (and often spread) Giardia. Currently, Giardia lamblia is the most commonly diagnosed intestinal parasite in North America. It is the most frequently identified cause of diarrheal outbreaks associated with drinking water in this country. Fully 20 percent of the world’s population is infected, and up to 7 percent of Americans, most without any symptoms at all. (Dr Rockwell's article) Those people who don't get sick are more and more likely to not treat water as time goes on. Seems logical that this could significantly skew interpretation of the surveys.

Perhaps it's something like "studies have shown that people who wear glasses can see no better than people who don't."

In Rockwell's famous paper, 69 water sources were tested, and Giardia was found in 1/3 of those water sources, but at levels too low to make people sick. That's all well and good. But for the sake of argument, let's just say 1 out of 100 water sources DO have concentrations high enough to make people sick. Out of 69 sources, the odds are good none will show dangerous levels of Giardia. But there might be 2, or 3 or even more sites showing dangerous levels of Giardia depending on what random water sources are tested, or even where in the water source the tests were made. A single study might show the water is almost perfectly safe, or drinking the water might appear akin to playing Russian Roulette with your health. Like my last Giardia doctor pointed out, the sample base seems to low to dependably extrapolate the results to the entire Sierra, let alone other backcountry areas.

[Ben Crowell]

Since we're seeing a lot of different figures on incubation time, I did some more research. There's a prepatent period, which is the time from infection with a parasite to when the bugs reach a life stage where they can be detected by a lab test. There's also an incubation period, which is the time from infection to symptoms. For most parasites, the prepatent period is shorter than the incubation period, but for Giardia it's often longer. Typically the period is about 8 or 9 days, but there's a wide range of variation, and it can take as long as months.

[Bob Gross]

The Giardia lamblia "bugs" often float around in the raw water in their trophozoan form, but they are large, like 25-35 microns, and easy filtering gets them. Once they get in your gut, they set up housekeeping. After a while, they release "eggs" or cysts, which are small, like 2-3 microns. That last stage is when the victim perceives symptoms. Often there are millions of cysts, and they exit and can be detected in a microscopic examination of a stool specimen. The more cysts there are, the more likely that they will be detected under the microscope, since the detection is sort of a scan process. If there was a relatively small number of cysts, like one thousand, they might escape detection unless the lab tech was really lucky. In general, the more extreme the symptoms are, the more likely that there will be a detectable number of cysts.

I've seen victims being treated for Giardia, and I would not want to wish that on my worst enemy.

–B.G.–

[Matthew Zion]

I'm a big proponent of no treating. Obviously there are situations where treating water is necessary or just the logical choice. My argument for going without is mostly based off evolutionary reasoning. I also am reluctant towards anything that uses the fear of what could happen to motivate support. However, I definitely agree with you guys addressing the articles stance on dehydration. I ran out of water in a 10 mile dry stretch on a pretty hot and dry day and actually got dizzy and stumbled down the trail the last couple miles to the water source, so I'll be drinking early, often, and even when I'm not thirsty.

[Buck Nelson]

all studies performed prior to 1996 did not use IMS (had not been developed), and thus the recovery efficiencies of the methods may be relatively low. http://www.waterbornepathogens.org/index.php?option=com_content&view=article&id=46&Itemid=72

The Sierra study, widely and often quoted, was done in 1984.

And here's a study which both supports and refutes my ideas on the subject. This paper distilled numerous existing reports on the topic:

CONCLUSIONS: Published reports of confirmed giardiasis among outdoor recreationalists clearly demonstrate a high incidence among this population. However, the evidence for an association between drinking backcountry water and acquiring giardiasis is minimal. Education efforts aimed at outdoor recreationalists should place more emphasis on handwashing than on water purification. Further studies should attempt to separate the specific risk factor of drinking water from backcountry sources from other behaviors among this group that may contribute to the risk. http://www.ncbi.nlm.nih.gov/pubmed/10737847

It's clear they conclude that there is no doubt about the high incidence of confirmed giardia for outdoor people. It's also clear there is no good data that shows people are getting Giardia from backcountry drinking water. It also seems clear that there's no good evidence that they're not, or they wouldn't say "Further studies should attempt to separate the specific risk factor of drinking water from backcountry sources from other behaviors among this group that may contribute to the risk."

[Tohru Ohnuki]

I just had to reup my BBP and first aid tickets so it's fresh in my mind and may bear repeating.

Disease transmission occurs when:
1) A pathogen is present
2) It's present in sufficient quantity
3) There is a correct entry site
4) The person is susceptible

1 and 2 basically mean if you have fewer than some threshold of a disease causing agent, then the disease probably won't occur. This will depend on the pathogen (some numbers i found are crypto ~100, giardia ~10, campylobacter 1000-10000, e coli 10-100) So filters usually specify what percentage is removed, say 99.999%, so if you start out with a million giardia per liter, 99.999% removed still leaves ~10 per liter. But it's hard to know definitively what level of contamination is present before filtering so source selection is a guide (eg, high sierra spring vs stream in a cow pasture)

3, well we're drinking the water so this is a gimme

4, This depends on each individual against each pathogen. Some people may be immune to giardia, others not. Most are immune to their own gut bacteria, but may cause others to become ill if there is fecal-food/water contamination and vice versa. There tend to be more claims of "I've never gotten sick" from solo hikers, so hell may be other people's gut flora…

[Ben Crowell]

Hi, Buck,

The Welch paper is referenced in my article, and I think it supports the overall conclusions I made.

I would actually be very interested in hearing from anyone who knows of scientific publications that go against the conclusions in my article. I don't know of any, but that doesn't mean they don't exist. It's easy to find a ton of statements contradicting my conclusions in apparently authoritative sources, such as Wilderness Press books or National Forest web sites. However, that's not the same as a scientific paper. I didn't consciously cherry-pick the papers I used, but it's true that, e.g., I often found out about paper B because it was one of the references in paper A, and of course the author of A is going to tend to cite papers that support his conclusions.

This discussion has been very interesting and helpful, BTW. I've been incorporating corrections, adding references, etc., as they turned up over the last couple of days.

-Ben

[James Marco]

I will go along with that. Most waters in the ADK's are pretty populated. The smaller waters are pretty clean. With the exception of an occasional rodent or beaver, it mostly remains a good clean source of water. That said, I treat the water pretty well, anyway. It will not bother on the current trip, but it might the next one. Maybe not, I often drink from the springs I find in the back country. Indeed, many of the springs were often piped out to the road for people to use. A common practice till the water scare started happening. Now it's comming back but more restricted than road side access. But, it still exists.

Why bother treating? Well, the wife insists on it. Or, I end up carrying 10lb of water. She has only recently accepted chemical treatments. Up to ten years ago, she insisted on boiled water only. With the kids…well, supermom was in overdrive 30 years ago. Even in summer, boiling a gallon in the morning and at night was the rule.

Anyway, she doesn't need to know about all the times I went fishing with nothing to drink.

[Buck Nelson]

The Welch paper is referenced in my article, and I think it supports the overall conclusions I made.

You did. And thanks for your rational responses. I'm not trying to be difficult, I'm just trying to argue my case. : )

How can you reconcile your statement "Myth: Backpackers get sick from Giardia in the water," with Welch's own "Further studies should attempt to separate the specific risk factor of drinking water from backcountry sources from other behaviors among this group that may contribute to the risk." Isn't he saying the relative risk hasn't been established? Is there a scientific study that you can quote that says backpackers don't or can't get giardia from water? What I see is papers saying the risks have been overblown. And they're probably right.

The Rockwell paper quotes an article that says the risk of contracting giardiasis in the wilderness is similar to that of a shark attack That doesn't square with Welch Published reports of confirmed giardiasis among outdoor recreationalists clearly demonstrate a high incidence among this population. Both scientific reports. At least Welch's is. Rockwell uses a little too much anecdotal evidence.

This is a good thread. I've learned a lot.

[John S.]

Myths about hydration-
– The 8 x 8 nonsense was debunked as early as 2000, so nothing more needs to be said in 2011?
– The "drink before thirsty" theory has also been gone since 2007.
– Thirst is not an instinct but is defined as the conscious desire for water, with the thirst center located in the brain. The thirst mechanism can be affected by age, drugs, disease, etc.
– The medical definition of dehydration probably is not primarily defined by any percentage since in the ER they won't know your previous weight, but rather by physical signs and symptoms along with laboratory testing. Neither will you attempt to treat it in the field by weighing your victim ; )
– For degrees of dehydration, I prefer something like mild dehydration (2-4%), moderate dehydration (4-8%), severe dehydration (8-10%)
– I doubt anybody ever said dark urine ALWAYS indicates dehydration. It MAY indicate dehydration in the appropriate setting. Urine color can be affected by disease, hydration status, foods, drugs, time of day, etc.
– If hiking solo and you become incapacitated, you may wish you had carried more than one liter of water. Take whatever risk you are comfortable with.
– Alcohol and caffeine are mild diuretics. While they may not dehydrate you, they very well may increase urine output in some persons.

[Jeffs Eleven]

Its funny people call alcohol and coffee (caffeine) mild diuretics. They both make me go twice per cup. A beer or a cup of coffee will often make me pee twice. I'm not arguing any point, just hoping I don't ingest major diuretics!! …probably should go to the doc

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