Posted by Bob R, 07-07-04

This topic has been addressed before but it seems timely again. For example, see (wpsmb_link). If you have the patience, you can spend a lot of time searching the literature for information on AMS, HACE, and HAPE. The Hackett/Roach paper has done this, and collects what was known as of three years ago. It is particularly valuable because all 76 references are listed, and you can cruise them to your heart's content. A useful summary, without references, is at

Note the statement in the first link: "The notion that over hydration prevents AMS has no scientific basis." There are people who argue against this, and I would like to be able to read their supporting information. Just because you over hydrated while climbing Mt. Whitney and didn't have any symptoms, doesn't mean your lack of symptoms was due to over hydration. Any more than me wearing my Tilley hat and not getting AMS means Tilley hats prevent AMS.

On the other hand, under hydration or dehydration will cause problems. Not that you will get AMS, which has clearly defined symptoms, but that you will feel poorly. There is a difference between having symptoms of AMS, and feeling poorly at high altitude because of dehydration. The former can be addressed by Ibuprofen and other actions, and the latter by drinking fluids. But water will not necessarily cure AMS, and Ibuprofen will not necessarily cure dehydration.

The point is: Just because you are sick at altitude does not mean you have AMS. The distinction is important, because the type of treatment differs. And the things you could have done to prevent your illness or minimize it are different. You need to know your enemy.

Having said all this -- that over hydration doesn't help but that adequate hydration is important -- I will say what I do. When I was younger I used to make it to the top (day climbs) in four hours or so. I would stop every hour and drink a liter of water, along with some food. So that's four liters up, and I would drink at most two on the way down: total of six for the day.

These days four hours up is beyond me, but seven or eight is doable. I find myself drinking about a half liter at my hourly rest stops. So again it's about four liters up, two down, and six for the day. I hasten to say that I never rush, so perhaps do not perspire as much as others who are going for time, for example.

Your needs may be different, but 4 + 2 = 6 works for me. I don't get AMS, but it's because I stay pretty much acclimatized all the time, and not due to good hydration. (However, I have learned over the years that, if I don't hydrate well, my appetite suffers and I don't eat, and my energy declines. And I don't feel well.)

Water on the Whitney Trail. Since many people seem to go up without a map, I thought I would list the places where good water can be found. Mileages and elevations are given, along with a few comments. Here's the link. (needs_link)

Posted by Tom S, 07-07-04
6 quarts sounds about right based on my experiences. I used 5 on my hike this past Monday (I'm smaller than the average male), and definitely had no problem with appetite. I usually haul of half of it from the Portal, starting with two quarts of freshly unsealed Gatorade (I'm a sucker for large, heavy daypacks), and tank up at the spring dripping on the north wall between Trailside and Trail Camp (not on Bob's list), and then coming down when I first hit the spring on the switchbacks. Thanks for the list and I'll sample some of them on future trips. Note that Consultation Lake is off the trail.

Posted by Wayne, 07-07-04
Thanks, Bob! That's the best water-source list I've seen for the Whitney Trail.

Posted by Memory Lapse, 07-07-04
Bob R,

Your post is about the best logical representation of the facts I have read on this board on this subject.

The only other thing I might have placed more emphasis on is the necessity for eating. Fruits contain the highest percentages of water by weight and is a significant source for hydration. They also have natural sugars instead of the processed stuff found in processed foods.

Note that nuts do not contain significant amounts of water but do caryy other needed nutrients (guess that's why trail mix caught on).

Almonds 7%
Apples 85%
Apricots 85%
Bananas 76%
Cantaloupe 91%
Carrots Raw 88%
Cheese American 37%
Cherries raw 80%
Grapes 82%
Olives 80%
Oranges 86%
Papyas Raw 89%
Peaches Raw 90%
Peanuts Shelled Trace
Peanut Butter Trace
Pears Raw 82%
Peas Raw 81%
Pecans 7%
Pineapple Raw 85%
Plums Raw 87%
Raspberries 81%
Strawberries Raw 90%
Tomatoes Raw 93%
Walnuts 4%

When I am hiking/backpacking I try to consume 250-300 calories of fruit, energy bars, and /or trail mix every two hours along with a good electrolyte replacement drink. To be honest I don't like any of the big three electrolyte drinks enough to use one exclusively over the other.

Thanks again Bob R for a great posting on the subject

Posted by sipako, 07-07-04
I agree that just because you don't feel well doesn't mean that you have AMS, but it was preached to me by the Himalayan Rescue Association that in the absence of contrary evidence, if you are feeling poorly at high elevations, you should assume it is AMS. Many people assume their problem is unrelated to elevation, and they continue to ascend, and the situation can get worse very quickly.

Posted by Cakie, 07-07-04
Dehydration contributes to AMS, this has been stated repeatedly in hundreds of different sources.

Posted by Cakie, 07-07-04
Scroll down to the third paragraph from the bottom:

I'm nagging on this issue because there are many newbies here or first time Whitney hikers. Goodness knows how many lurkers there are out there who never post but read everything. I feel it is a terrible affront to state repeatedly that hydration is unimportant, unrelated to AMS, etc. This can (and probably will) convince many of these new hikers to think, "Heck, I don't need no fluids going up. These 'experts' here say I ain't got no need to drink nothin' and I ain't totin' no extra water, so there."

People read this board and place emphasis on the opinions presented as fact here. I am saying this emphatically: hydrate, hydrate, hydrate when you're hiking. I've seen people at Bryce and Zion who nearly died from heat stroke because they didn't drink. AMS symptoms might be preventable in some cases by hydrating. This nonsense that hyponatremia might occur is ridiculous. You have to drown in fluids for this to happen and eat nothing.

I don't think 20-25 ounces of water per hour while doing Whitney is unreasonable or absurd or the basis for castigating the suggestion. It's a sound and smart piece of advice.

Posted by Cakie, 07-07-04
Beating a dead horse... guess these guys climbing Everest know nothing about AMS and hydration:

Posted by Cakie, 07-07-04
The guidebook used by the 1999 Everest team attempting to summit from Canada had this written in their guide, used by guides leading people up Everest:

"Proper and adequate hydration is critical. In fact, "mandatory" is not too strong a word-to preventing acute mountain sickness (AMS). Often the headaches, nausea, and dizziness associated with AMS can be prevented with proper hydration. One problem in diagnosing AMS is that it can be confused with dehydration, carbonmonoxide poisoning, etc. Headaches, nausea, and dizziness should be attributed to AMS (or altitude) until proven otherwise.

You can clear the air by making a strong effort to stay hydrated so that dehydration is not part of the differential diagnosis. One way to gauge dehydration is to monitor the urine output. Scant amounts of dark yellow urine indicate dehydration. The lighter the color and the more frequent the urination, the better the state of hydration. Especially as it relates to AMS, it is crucial to emphasize to your clients the critical importance of hydration. It can mean the difference between life and death above base camp. AMS is not an inevitable feature of Everest climbing; it is preventable and treatable."

Posted by AlanK, 07-07-04
BobR started this thread by saying that he drinks 4 liters going up and 2 going down. Everyone else either agrees with him or recommends more. So, how does the newbie get the message "I don't need no fluids going up"?

1 liter is 1 kg = 2.2 lb = 35.2 oz, so 6 liters is 211 oz, or 17.6 oz per hour for a 12 hour hike. That's not bad -- BobR is recommending 70-88% of your recommended 20-25 oz per hour.

The flaw in your recommendation lies in the belief that a person who does the same hike in twice the time requires twice the water intake.

Posted by Tucker, 07-07-04
Cakie -

I read that excerpt from guidebook of the 1999 Everest team attempting to summit from Canada as saying that hydration is critical in order to be able to rule out dehydration as a possible cause of the headaches, etc, associated with AMS. Dehydration and AMS have very similar symptoms. If someone is at the elevations, especially of Everest, and ignores the symptoms of AMS, thinking they're simply dehydration, it could jeapordize not only that person but the whole expedition.

We all agree that hydration is important. For those of us *knock on wood* that are not strongly affected by AMS, hydration can keep us healthy and therefore less likely to fall victim to AMS.

For those afflicted by AMS every time they go "high", then being hydrated is as important if not more so as a way to rule out hydration as a cause for the symptoms. Overhydrating will do nothing more for them.

Posted by Memory Lapse, 07-07-04

Thank you for providing information on a subject that you obviously feel very strongly about. I agree with your motives to provide this information because "there are many newbies here or first time Whitney hikers". So as a result of all the information provided here I did some research.

I have concluded that everyone reading this thread recognizes the importance of proper hydration; I think the disagreement is the relationship between hydration and AMS. There absolutely is a correlation between the two but I have found suggestions from other qualified sources that don't fully support your point of view. I have no way of validating their authenticity but they appear to be reputable sources. One of particular interest is

The owner and principle content provider of this website is Thomas E. Dietz, MD. One published article of Dr. Deitz states "Altitude headaches are usually nasty, persistent, and frequently there are other symptoms of AMS; they tend to be frontal (but may be anywhere), and may worsen with bending over. However, there are other causes of headaches, and you can try a simple diagnostic/therapeutic test. Dehydration is a common cause of headache at altitude. Drink one liter of fluid, and take some acetaminophen or one of the other analgesics listed above. If the headache TOTALLY resolves (and you have no other symptoms of AMS) it is very unlikely to have been due to AMS."

Now his statement does not discredit your notion that dehydration (or a lack of proper hydration) is a cause for AMS, but instead concludes that dehydration is a cause of headaches (a symptom of AMS) and suggests a treatment to determine if the symptom is due to AMS or some other malady.

Now this guy may be wrong but a review of his credentials is impressive. Also, I think it important to note that his website does NOT promote any specific products.

I also read with interest the sources you provided and each of them offers some very good advice. However, some things about the sites that distressed me were:

Website # 1 - - This page states "Drink-up. Dehydration contributes to altitude sickness, so keep that canteen handy!" -- This is hardly an overwhelming set of facts and findings to support the notion that the prevention/cure for AMS is hydration, hydration, hydration. I feel certain the author has some qualifications but I need more foundation to her point of view.

Website # 2 - - This site is dedicated to the pursuit of PARAGLIDING. The html page referenced above is attached to an ad for Camelbak.

Website # 3 - - A great site, thanks for sharing. Only there is not a single mention of AMS on this page AND the topics titled "AMS" and "Prevention of AMS" on this site do NOT have the words "water", "liquids", "fluids", "hydration", or "dehydration" mentioned on them.

I was very amused to find the flowing website: It has a water consumption calculator to help people determine how much water they should intake during exercise. If I followed their advice, I would develop more blisters on my hands from filtering water than on my feet walking the 20 plus roundtrip miles on Whitney. Oh, by the way, it is sponsored by a boatload of bottled water companies.

Probably the singularly most important fact I learned from this venture was that AMS is caused by a rapid increase in elevation without proper acclimatization. The most immediate treatment is to stop climbing and acclimatize at the current elevation OR descend.

So Cakie, if you never experience AMS and you actively hydrate on your trips, I think you are very lucky. Your suggestion of 20 -- 25 ounces per hour is a reasonable rfecommendation. It calculates out to 7.09765 -- 8.87206 liters for 12 hours which is not much more than the 6 liters Bob R uses.

Once again your motives are correct, I just think hydration alone is not the answer.

Posted by GoingBackSoon, 07-07-04
Dehydration has some of the same early symptoms as altitude sickness. I wonder how many are beat, tired, dehydrated, exhausted etc. and blame it on Altitude sickness. It can be one, the other or a combination of both.

If you actually have altitude sickness, you take a pain killer and go a little higher (like 1000 feet) and it gets much worse. You can persist through exhaustion, but not progressing altitude sickness. It does you in, with or without help. Exhaustion and dehydration respond postively to resting, eating and drinking,... altitude sickness does not.

I believe Bob R. is correct. Just because you drink lots of water doesn't mean you won't get altitude sickness. If I drive from sea level, get out of the car and start hiking, I will have altitude problems by about Mirror lake every time. I have no chance of making it higher, even if I drink plenty of water.

Posted by Bob R, 07-08-04
The comprehensive Hackett survey paper (Hackett PH and Roach RC. High Altitude Illness. N Engl J Med 2001; 345:107-114) gives the risk factors for AMS: a history of high-altitude illness, living below 3000', exertion, and certain preexisting cardiopulmonary conditions. It does not mention dehydration. This doesn't mean dehydration isn't a factor; just that, in their exhaustive survey of the literature, it hadn't been reported.

When the subject is controversial, I try to dig into information from truly credible sources, usually peer-reviewed medical and scientific journals. Although I didn't go looking for it, I haven't been aware of a documented connection between dehydration and AMS. Lots of conjecture and opinion - especially in this Internet age when both good and bad information reproduce exponentially - but no documentation that I have run across. So I didn't dwell on it in my original post.

And it doesn't matter. If you get sufficiently dehydrated during exercise, you will get sick. If you have AMS in addition, you will feel even worse. The message is: Drink enough during your climb, and it doesn't matter if your intent is to ward off AMS or to avoid the problems of dehydration, or both.

AMS is a syndrome of nonspecific symptoms and is therefore subjective. There is an accepted definition of AMS, developed at the Lake Louise Consensus a dozen years ago: Headache in an unacclimatized person who has recently arrived at an altitude above 8000', plus the presence of one or more of the following: gastrointestinal symptoms (anorexia, nausea, or vomiting), insomnia, dizziness, and lassitude or fatigue. Hackett mentions a study that found that 42% of the people going to 10,000' contracted AMS. (Dean AG, Yip R, Hoffmann RE. High Incidence of Mild AMS Sickness in Conference Attendees at 10,000' Altitude. J Wilderness Med 1990; 1:86-92).

So: If you are not acclimatized and are feeling poorly high on Mt. Whitney, there is a pretty good chance you have AMS. If true, there are some things you could have done in advance (too late now!), and there are some things you can do now to alleviate it. These have been addressed on this board numerous times. If not AMS, ... well, you have to figure out what it might be, and treat it.

My original thesis was to point out that over hydration does not prevent AMS (at least from what I have read), because a number of people had been alluding to it recently. I took the opportunity to point out again that good hydration is very important. No matter what illness you fear.

Posted by Bill Law, 07-08-04
Here's BobR's list of water sources (for those lacking MSWord). Note that "I" in the comments after the list is BobR speaking, not me...

Reliable Water Sources Along the Mt. Whitney Trail

Location Mile Elevation Comment
1. Carillon Creek stream crossing 0.5 8600 From the slopes to the north
2. North Fork LP Creek stream crossing 0.6 8800 From Lower Boy Scout Lake
3. Cascade by downed log, below LP Lake 2.5 9900 Stream from Bighorn Park
4. South side of Bighorn Park 3.7 10360 Spring from the north slopes of Candlelight Peak
5. Stream by Outpost Camp 3.8 10360 From Mirror Lake; see 6. below
6. Stream from Mirror Lake 4.3 10640 Can have minor organic matter late in the season
7. Stream from Trailside Meadow 4.8 11150 In spring and summer, most comes from Consultation Lake
8. Trailside Meadow 5.3 11390 Later in the season, most comes from the Trail Camp area
9. Consultation Lake 5.8 11700
10. Trail Camp Lake 6.3 12040 Next to Trail Camp
11. Stream feeding Trail Camp Lake 6.3+ 12040 Just west of Trail Camp Lake
12. Spring near Switchback #23 6.7 12400 Flows May - October; may freeze at night

* While I don't worry about the water at 3., I usually (not always) push on to 4. to drink up. Since 4. is a spring, it's probably more pure than most city water.
* Water in Trail Camp Lake is almost universally avoided by campers and hikers, but it is probably OK most of the time. Nevertheless, it is easy to walk 100 feet to the fine clean stream feeding it, which comes from a series of lakes west and north of Wotan's Throne. So I avoid 10.-not because I fear it but because 11. is so handy.
* The spring near Switchback #23 comes from snow slopes south of the trail. It cascades over the trail several times before going back underground, but I usually get my water from the highest such crossing, or from the spring itself (about 30 feet south of Switchback #23).
* When the streams are flowing full, I do not hesitate to drink untreated water from any of these sources. Later, come August or so, I'll pass up 3., 5., and 6., although they are probably still OK.
* For information about Giardia in the high Sierra, go to Because of recent measurements of the existence/nonexistence of organisms such as E-coli O157:H7, I plan to update that paper to include the new information one of these days. In the meantime you can read and to decide if you want to worry about it. (Note: The 1% mentioned in the first paper doesn't mean you have a 1% chance of ingesting something bad if you drink untreated high Sierra water. "Drinking smart" can reduce this chance to virtually nil.)

Posted by Alpine Swine, 07-08-04
Cakie, Thank you for providing information on a subject that you obviously feel very strongly about.

Cakie and I did this on another thread. While I myself try to drink as much water as is possible on any route up any mountain, certain realities exist. Each liter weighs a couple of pounds while a liter of white gas (for melting snow/boiling water) weighs a half pound or so less. We all make decisions every day and live with them.

On Whitney it seems with the abundant water sources carrying a filter and drinking extra while pumping should obviate any AMS concerns Cakie has. My guess is that it won't as AMS is a fairly complex animal.

Since Cakie brought up Everest I should note that my recent trip up the Kautz on Rainier was led by an Everest summiteer who was vigilant about the amount of weight the team was carrying in all situations.

Water in your pack is a liability on a serious route. Mountaineers around the world climb on two liters per day (10-12 hours) after starting hydrated in the morning and then making up the difference sucking down 'hots' at night before dinner. For me if I pee out a liter in the tent (well marked bottle) at night I know I'm in the zone.

Cakie needs to realize that Whitney is, despite the highway to the summit, A FAIRLY BIG ASS MOUNTAIN. As such it should be accorded the appropriate respect which includes being able to modify your personal needs to accomodate what the mountain demands of you. There is no such thing as perfect on a mountain.

Posted by rosabella, 07-08-04
BobR - do you have a similar list of Reliable Water Sources on the Mountaineers Route?

"What we have done for ourselves alone dies with us; what we have done for others and the world remains and is immortal." Albert Pike

Posted by Bob R, 07-09-04
OK. It's of much less interest and this seems like a strange thread to embed it in, but ... here. (needs_link)

In this list, and in the one above for the main trail, I emphasize my belief in the purity of the water sources. You are free to treat it if you want, of course; I won't be offended!

Posted by gatormom, 07-09-04
Bob R,

In your reliable water sources along the Mt. Whitney Trail, you mentioned Switchback#23. Is the Switchback #23 marked, or do I have to count how many Switchbacks myself.

For that matter, is there mile marker posts all along the main trail?

Posted by Bob R, 07-09-04
The switchbacks are not marked, but Wayne Pyle has counted them and every now and then reminds the board. Last time was about two weeks ago:


Go to that link for an explanation, and a link within to see the map.

There used to be mileage markers, but they have not been maintained and some have undoubtedly disappeared completely. There are two left I can recall at the moment; see below. The first one is around 20 feet above Trailside Meadow, and the second is between Switchback nos. 94 and 95. For accuracy, you'll have to add 1/4 mile or so, because they were put in before the newer (longer) trail start at the Portal.

But the quick answer is no, there are no useful mileage markers.

Posted by Marc, 07-09-04
"And it doesn't matter. If you get sufficiently dehydrated during exercise, you will get sick. If you have AMS in addition, you will feel even worse."

This simple statement by Bob has been true for me. Regardless of elevation, if the hike is strenuous I need to drink and eat regularly or I feel cruddy. But the additional point I've noticed personally is that hydrating well seems to make a difference in whether I get leg cramps or not. I know I'm going to get a little headache and lose my appetite at altitude, but it's those cramps I really hate. If I'm drinking regularly, adding the Hydrolite, stretching a little after breaks, I'm able to avoid them.

Thanks for the water location info. Just this year I switched to carrying less water, filling up more often along the way when needed, and ditching the filter...just use iodine if I'm feeling that the source is shakey. What a relief in pack-weight. By the way, I looked around a little a few weeks ago for that old trailhead past the store, but couldn't find it. 1/4 mile shorter, eh? Kind of appealing.

Posted by SummitSeekr, 07-09-04
Just a little FYI on the trail mileage markers. A few years ago I contacted the local forest service and told them I'd bother to take up a little can of paint and a brush to refresh the fading markers.

Well, they had an absolute hissy fit saying that the markers detract from the pristine nature of the trail. I don't think they do. I always found them very helpful, especially to newbies who've never been on the trail and don't rightly know where they are.

Posted by Bob R, 07-09-04
SummitSeekr, I couldn't agree more with your assessment. Compare the visual impact of some blue paint on a small rock, a spare ten times between Portal and summit, with that of (say) 97 switchbacks hewn into a 3000' x 1500' slope!

Of course, trails help the experience. But signs do, too. Fortunately, they do tolerate both here and there. But I wonder how anyone could be bothered by some small blue letters on a rock, and not be offended by the incongruity of the big metal sign at the top of Shepherd Pass, several square feet in area, for example.

Posted by Memory Lapse, 07-09-04
Personally I find some of the clothing people are wearing on their hikes to be far more distracting than information that helps hikers navigate.

Wonder how many times over the years those mileage markers were referenced to get someone injured person some assistance?