The Best Hydration | Drink When Thirsty

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Drink When Thirsty

Drink When Thirsty debunks the many myths about hydration and dehydration like “If you are thirsty, it’s already too late” and  “If your urine is yellow, you are dehydrated.” This article suggests that Drink When Thirsty is the best and healthiest strategy for hydration during exercise.

It turns out that your body’s natural, thirst mechanism (700 million years old) works well to keep you hydrated and healthy during exercise. In fact, the amount of water your body requires is probably far less than what the Sports Drink and Bottled Water companies have been telling us.

People may be drinking too much water…

With all the hype about the risks of dehydration, it is actually over hydration (hyponatremia) that may be more of a risk. People are now having serious health problems from over hydration for endurance races and even hiking in the Grand Canyon—sometimes resulting in death1,2,3. [Note: Since I first published this post it has been shared by numerous Emergency Medical Treatment and Search and Rescue organizations for this very reason.]

Learn more about choosing between our favorite backcountry filters – Sawyer Squeeze vs Katadyn BeFree vs Platypus Quickdraw and hiking water bottles.

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Best hydration system

Best Hydration and Purification System – It’s NOT Complicated!

The simple, inexpensive Hydration and Purification System that Alison and use is shown above. When “drinking to thirst,” it has kept us well hydrated — even between distant water sources in the desert.

Excerpted from my 9 Pound – Full Comfort – Lightweight Backpacking Gear List:

  1. Sawyer Squeeze Filter: We can drink immediately at water sources. This means both quick, effective hydration and less water to carry when we hike.
  2. Water Treatment Tablets: For fast, efficient water purification in camp. We can treat 3 or more liters of water in less than a minute. And it’s ready to drink 20-30 minutes later.

Drink When Thirsty – Myths and Facts about Hydration

I recently interviewed three world experts in the field of sports hydration (not affiliated with Sports Drink and Bottled Water companies)

  • Dr. Marty Hoffman, MD, founding member of the Foundation for Medicine & Science in Ultra-Endurance Sports, a member of the Wilderness Medical Society, and professor at the University of California Davis
  • Dr Tamara , D.P.M., Ph.D., Associate Professor of Exercise Science, Oakland University, Rochester, MI
  • Dr. Kristin Stuempfle Ph.D, Professor, Health Sciences, Gettysburg College

This is what I learned from these experts…

Myth1 – If you are thirsty, it’s already too late
Correct – Drink When Thirsty

  • All the experts in sports hydration I talked with adamantly agreed that Drink When Thirsty is the best and healthiest strategy for hydration during exercise*.
  • As Dr. Hoffman’s puts it: “Drink When Thirsty works for prolonged exercise. Our bodies have a fine tuned feedback system that lets us know when to drink…there is no real danger of dehydration when people have access to water. Thirst kicks in, and people drink.”
  • This agrees with the recommendation from the Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, 2015to Drink When Thirsty; “Using the innate thirst mechanism to guide fluid consumption is a strategy that should limit drinking in excess and developing hyponatremia [over-hydration with significant health consequences] while providing sufficient fluid to prevent excessive dehydration.”
  • Excessive drinking when you are not thirsty increases the risk of hyponatremia, arguably a greater risk than dehydration.

*Dr. Tamara Hew-Butler says the natural thirst mechanism has been working in animals and keeping them well-hydrated for at least 700 million years. See more from Dr. Hew on how the human thirst mechanism works.

So why have we been told to drink, drink, drink?

Why do we continue to hear sayings like, “hydrate or die,” “if you are thirsty, it’s already too late,” and stating that “your athletic performance will drop if you don’t drink enough“?

Deborah Cohen, investigations editor for the BMJ [formerly British Medical Journal], wrote up her findings in the 2012 feature article, “The truth about sports drinks5“. This article implies that the sports drinks industry has dramatically increased sales of their products by:

  1. Creating a “disease of dehydration”
  2. Stating that the natural thirst mechanism is inadequate to keep athletes hydrated. [Cohen implies that the evidence for this view is lacking.]
  3. And that this “lack of evidence” is in part due to the close financial and other affiliations between the sports drink companies and the scientists/researchers and supporting institutions that produce the research to support this view.
  4. Cohen’s article gives examples of studies supporting the sport drink companies claims, that when reviewed by an independent panel of experts, are not deemed robust enough to support those claims.

Here are some excerpts from the article

“Sports drinks are increasingly regarded as an essential adjunct for anyone doing exercise, but the evidence for this view is lacking. Deborah Cohen investigates the links between the sports drinks industry [e.g. Powerade (Coca-Cola) and Gatoraide (PepsiCo)] and academia that have helped market the science of hydration.”

‘“The problem was industry wanted to sell more products so it had to say that thirst was not adequate,” Noakes [Professor Tim Noakes, Discovery health chair of exercise and sports science at Cape Town University] says.’

‘Disease mongering is a well documented phenomenon in healthcare6 and Noakes suggests that industry has followed a similar pattern with dehydration and exercise.

“When industry wanted to sell more product it had to develop a new disease that would encourage people to overdrink,” he said adding: “Here’s a disease that you will get if you run. Here’s a product that is going to save your life. That’s exactly what they did. They said dehydration is a dreaded disease of exercise.”’


Debunking Other Hydration Myths

The following debunks:

  • You need to drink a liter per hour
  • Dehydration is a big problem
  • If your urine is yellow you are dehydrated
  • Dehydration causes cramping

And finally it address the Big Question, “How much water should I drink/carry on a hike?

Myth2 – You need to drink a liter per hour
Correct – Drink When Thirsty

  • Again, Drink When Thirsty is the best strategy.
  • Dr. Kristin Stuempfle says that studies7 show that the human body can only process a maximum of  0.8 liters (27 oz) to 1 liter (34 oz) of water at rest. That is not what your body needs—just the maximum amount of water it can process if needed—an important distinction.
  • That maximum amount of water processed will go down during exercise. According to Dr. Stuempfle our body’s natural response to exercise is to shunt blood from the kidneys and the GI (stomach and intestines) and  put it toward motor (leg) muscles, heart, and skin (cooling). In addition, during exercise the body secrets a natural antidiuretic hormone (ADH) to slow urine output. All these combine to reduce your body’s ability to process water.
  • So if you drink more water than you need during exercise (i.e. not drinking to thirst) then your body is receiving more fluids but has less capacity to handle them. Thus the risk of overhydration, and possibly hyponatremia.
Drink When Thirsty

In cooler environments where water is plentiful you may not need to carry any water with you. Drink from the source, and you will likely not be thirsty when you reach your next water source.

Myth 4 – Dehydration is a big problem
Correct – Mild dehydration is not a cause for serious concern

  • It will not significantly impair performance or health
  • Dr Hoffman told me:  “Even a mild hydration deficit of 2-3 liters is OK (provided you were adequately hydrated at the start of your hike). You may not be happy about it, but it’s not a serious problem.
  • Dr Hoffman also told me: “Top ultra runners are still performing well late in the race [100 miles] with a few percent bodyweight loss. They could not perform as well as they do, if percent bodyweight loss and mild dehydration was a big impediment to race performance8,9.”

Myth 5 – If your urine is yellow you are dehydrated
Correct-  Urine naturally turns yellow during exercise, even when adequately hydrated

  • Dr Hoffman says that: “Trying to keep urine clear during exercise will cause over hydration.” There was complete agreement among all the researchers on this point.
  • Additionally Dr Hoffman said: “[during exercise] urine color is not useful, and should not be used, as an indicator of hydration status…During exercise, because of hormonal influences to retain fluid and blood flow being shunted away from the kidney, urine production should be diminished, so urine color will darken.”
  • And from Cohen’s article5: “The science of dehydration has led to another widely held belief that is not based on robust evidence—that the colour of urine is a good guide to hydration levels.” And also from Cohen’s article5: “There is a lack evidence for the widely recommended practice of assessing hydration status by looking at the colour of urine,” it suggests.

Myth 6 – Dehydration causes cramping
Correct – Cramping well understood but not likely from dehydration or electrolyte levels

  • All the researchers I spoke with agreed that cramping is complex, not well understood and likely has multiple causes.
  • They also agree that dehydration and electrolyte depletion are not likely the main causes.
  • Dr. Hoffman not only noted that cramping appears to be neuromuscular, but that dehydration or electrolyte depletion does not cause cramping. Dr. Hoffman said this finding has been known for a number of years. In fact, cramping has more to do with neuromuscular nerve misfiring—nerves sending a false signal to muscles to contract and stay contracted, as indicated in research10 by  Martin P Schwellnus, UCT/MRC, Research Unit for Exercise, Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, South Africa.
  • From the New York Times Article A Long-Running Mystery, the Common Cramp by By GINA KOLATAFEB. 14, 2008:
    • “DR. SCHWELLNUS proposes that the real cause of cramping is an imbalance between nerve signals that excite a muscle and those that inhibit its contractions. And that imbalance, he said, occurs when a muscle is growing fatigued.”
    • “There’s the dehydration proposal: you just need more fluid. But, Dr. Schwellnus said, he studied athletes who cramped and found that they were no more dehydrated before or after a race than those who did not have cramps.”

How much water should I Drink/Carry on a hike?

This is the big challenge for backpackers, day-hikers or others that need to carry enough water between distant sources. Unlike Dr. Hoffman’s “There is no real danger of dehydration when people have access to water,” there is a possibility that if we don’t carry enough water between distant sources that we could run out of water and potentially become dehydrated. On the other hand, if we are hiking a long distance between water sources and and decide to carry 5 liters of water we are carrying an additional 11 pounds. This too has serious downsides.

So the big question for hikers and backpckers is

How do you estimate the “right” amount of water to carry between distant sources?


The goal is homeostasis, or to drink the same amount of water as your body uses. But how do we estimate our personal water consumption needs for homeostasis in the field? There is likely no “right or exact” answer to this. Dr. Stuempfle and Dr. Tamara Hew-Butler agree that the following would be a reasonable strategy for individuals to estimate their personal water consumption in the field:

  • On test day-hikes (or a weekend backpacking trip), Drink When Thirsty and record the amount of water your drink per hour. Try to do this close to the same level of exertion, and temperature and humidity that you will expect on your backpacking trips (or long day hikes).
  • Use this consumption rate per hour as a starting point for estimating the amount of water you’ll need to carry between distant sources in the field for your longer and more serious trips.
  • It is best to be conservative (carry a bit more water) until you have tested out and fine tuned your personal water consumption rate over at lest a few longer trips in the field.
  • Obviously if it is hotter, more humid, you are working harder, or your pack is heavier, you may need more water per hour. But, if it is cooler, less humid, or you are not working as hard, you may need less water per hour.

On a personal note, when following Drink When Thirsty I frequently do not carry any water with me in the field (Sierras, Appalachian Trail, etc.). When I drink (using aSawyer Squeeze Filter so I can drink directly at the source), I find that I am unlikely to be thirsty until I reach the next water source. My wife seems to run a bit thirster, and in addition to drinking at water sources, she usually carries somewhere between ½ to ¾ of a liter between sources.


Although I rarely carry water with me, the desert is the exception. This picture is from a drought year in the Southern Utah desert. So an unusually dry time in an already hot and dry place. I have collected a lot of water: for dinner that evening, breakfast the next morning & to carry during the day to our next reliable water source.

The only place we carry large amounts of water between sources is in the Desert Southwest, like Canyoneering in Utah. But even then, following Drink When Thirsty, we carry less water than the “recommended” amounts in guide books and other “authoritative” sources. We pull long days in the desert and feel healthy and fine. But we have years of field experience and comfortably know our personal water needs in the desert.

How the natural thirst mechanism works

Dr Tamara Hew-Butler, who has studied the natural thirst mechanism in animals, says it’s been working to keep them well-hydrated for at least 700 million years. The human thirst mechanism functions in two ways:

  1. Brain sensing electrolyte levels11: Your brain has real-time osmosensors that monitor sodium concentrations (more specifically, the amount of osmoles, for which sodium makes up the greatest amount) circulating in the blood. When sodium levels start to rise above normal, your body has a two stage response. The first response, is to slow urine output and therefore water loss (this occurs before thirst is triggered). If sodium levels continue to rise, your thirst mechanism kicks in and you become thirsty. It is important to note that you are NOT dehydrated at this point. All this happens before dehydration becomes an issue. This is your body’s normal mechanism to keep you from getting dehydrated. Dr. Hoffman and Dr. Hew-Butler both point out that as long as folks have access to water, their thirst will cause them to drink and not become dehydrated.
  2. Your heart (actually the main valves) senses blood volume (water): Your heart valves have barorreceptors that can detect a reduction in blood volume (water in the body). This also has a two stage response just the same as the brain’s osmosensor responses. Stage 1 happens at an 8-10% blood volume depletion and triggers an anti-diuretic hormone release which slows urine output and therefore water loss. You are not thirsty at this point. If blood volume continues to decrease, your thirst mechanism kicks and you get thirsty. Again note: that you are NOT dehydrated at this point. All this happens before dehydration become an issue. This is your body’s normal mechanism to keep you from getting dehydrated.

Figure source: 11 – INADEQUATE HYDRATION OR NORMAL BODY FLUID HOMEOSTASIS? – Tamara Hew-Butler, PhD, LETTERS, American Journal of Public Health, October 2015, Vol 105, No. 10, page e6


Drink When Thirsty, it’s been keeping hominoids well hydrated for millions of years.

Drink When Thirsty


1 Three Cases of Severe Hyponatremia During a River Run in Grand Canyon National Park – Emily A. Pearce, BS, et al., WILDERNESS & ENVIRONMENTAL MEDICINE, 26, 189–195 (2015)

2 Hiker Fatality From Severe Hyponatremia in Grand Canyon National Park – Thomas M. Myers, MD, et al., WILDERNESS & ENVIRONMENTAL MEDICINE, (2015)

3 Exercise-associated hyponatremia with exertional rhabdomyolysis: importance of proper treatment – Martin D. Hoffman1, et al., Clinical Nephrology, DOI 10.5414/CN108233

Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015 – Hew-Butler, Tamara DPM, PhD, et al., Clinical Journal of Sport Medicine: July 2015 – Volume 25 – Issue 4 – p 303–320, doi: 10.1097/JSM.0000000000000221

5 The truth about sports drinks – Deborah Cohen investigations editor, BMJ 2012;345:e4737 doi: 10.1136/bmj.e4737 (Published 18 July 2012)

6 Moynihan R, Heath I, Henry D. Selling sickness: the pharmaceutical industry and disease mongering. BMJ 2002;324:886.

Peak rates of diuresis in healthy humans during oral fluid overload – Noakes TD, et al., 2001 Oct;91(10):852-7. PMID:11732457

8 Race Diet of Finishers and Non-Finishers in a 100 Mile (161 km) Mountain Footrace – Kristin J. Stuempfle, PhD, Martin D. Hoffman, MD, Journal of the American College of Nutrition, Vol. 30, No. 6, 529–535 (2011) page 529

9 Association of Gastrointestinal Distress in Ultramarathoners With Race Diet – Kristin J. Stuempfle, Martin D. Hoffman, and Tamara Hew-Butler, International Journal of Sport Nutrition and Exercise Metabolism, 2013, 23, 103 -109

10 Cause of Exercise Associated Muscle Cramps (EAMC) — altered neuromuscular control, dehydration or electrolyte depletion? M P Schwellnus, British Journal of Sports Medicine 2009 43: 401-408 originally published online November 3, 2008 doi: 10.1136/bjsm.2008.050401

11  INADEQUATE HYDRATION OR NORMAL BODY FLUID HOMEOSTASIS? – Tamara Hew-Butler, PhD, LETTERS, American Journal of Public Health, October 2015, Vol 105, No. 10, page e5

47 replies
    • Alan Dixon
      Alan Dixon says:

      For regular hiking and backpacking plain water is best. We like to get our calories from real food, and our hydration from real water. It’s worked for humans for millions of years. Best, -alan & alison

  1. C.
    C. says:

    This was a tremendous help as I am beginning to manage the amount of water-carry to get pack weight down without sacrificing my required water consumption, plus the need for that little extra when solo-ing just to be safe.

    I am wondering if I could convert the Sawyer squeeze with an adapter onto my platypus creating an inline configuration. I carry the bladder in the outside pocket of my MLD pack. I am thinking I could always have 3/4 to 1 litre water in the bag and let the filtering happen on the fly. Thanks so much. C.

    • Alan Dixon
      Alan Dixon says:

      Hi C and apologies for the late reply. I’ve been guiding Alaska’s Brooks Range for the last two weeks and will soon head back in to Alaskan mountains for another two weeks. That setup is certainly doable, altho the most common filter for this is the Sawyer Micro. It already has a tubing adapter on both ends so it’s easy to “splice” into Platypus hydration bladder. The problem with the Mini is low flow rate and it’s prone to clogging. If you want to use the new Micro or the traditional Squeeze you’ll need the Sawyer Fast Fill Hydration Pack Adapter Kit. This will allow you to get higher flow rates and less risk of clogging. Also you have the flexibility to attach it directly to a squeeze pouch. But honestly, Alison and never use a hydration system, even in the desert. We find that the Squeeze on a bladder is all that we need. Simpler, lighter, easier to clean. Less parts to fail. But whatever works for you. Wishing you some great trekking this year. Warmest, -alan & alison

      • C
        C says:

        Hi A, Thanks a million for the great advice. As a solo hiker, I don’t have anyone to take the stuff out of my pockets! The setup of the Sawyer mini and bag is quite tall! Therefore I like the idea of the inline sawyer on the platypus bag which I keep in the big outside pocket on my MLD bag. I agree the sawyer mini clogs quickly so I will try the Micro as you suggest.

        Thanks as always and enjoy yourselves out there as I will too!

  2. BrianS
    BrianS says:

    Very interesting article & well written. It is great that you added the sources as well.

    One question – what is Myth 3?


  3. Todd Anderson
    Todd Anderson says:

    Great article Alan! Thank you for sharing. I found it very helpful. One thing that might be good to highlight to your readers is that when using the water purification tablets or drops (chlorine dioxide), it takes 4 hrs to kill cryptosporidium. Everything else is killed in 30 mins. That information is from the Aquamira website. I don’t have my drops or tablets handy right now so I can’t check the direction on the labels.

    • Alan Dixon
      Alan Dixon says:

      Yes, Todd 4 hours is correct for crypto. It has a hard shell that takes the chemicals some time to penetrate. If you suspect that crypto is prevalent in an area then the Sawyer filter is likely a better filtration option. The downside of the filter is that it does not get viruses. Best, -alan

      • Todd Anderson
        Todd Anderson says:

        OK. I’ve never looked into what was in the water sources where I was going. I just treated for the worst case. But I may consider researching that in the future. It would be nice not to wait 4 hrs. How easy or hard has it been for you to uncover water issues where you are going?

        • Alan Dixon
          Alan Dixon says:

          Generally, in North America I assess individual water sources for their potential for contamination from human or animal impact at the site up drainage from it. and make a call on how to treat it. Outside NA I usually treat as if their is potential for both microbial and viral activity. Hope this helps, -alan

        • Todd Anderson
          Todd Anderson says:

          Ah! I at first thought you were doing some research online before your trip. What you just said makes perfect sense. I appreciate you taking the time to respond! And thank you for all the great content you have created – it is really excellent :)

  4. Russell Ely
    Russell Ely says:

    Hi Alan,

    I typically use a Sawyer filter mini with Sawyer and Platypus pouches. The pouches fill easily in running streams however, I find them difficult to fill in a lake. Do you have suggestions for harvesting water from lakes?

    • Alan Dixon
      Alan Dixon says:

      Sorry for the late reply. I was guiding for three weeks with very limited connectivity. Yes there is a way to do this. You need to inflate the bladder (a puff from your mouth is fine). Then with it upside-down/opening at the bottom slowly immerse it into the water. Once immersed SLOWLY rotate it until air starts to slowly bubble out of the opening. Continue to rotate SLOWLY towards upright. If you do this slowly enough you will have the bladder about 90% full. If not, try again and do it more slowly. There is an art to it. Hope this helps, Warmest, -alan

  5. Jennifer Faoro Weller
    Jennifer Faoro Weller says:


    Not carrying a lot of water was one of the hardest changes I’ve made in revamping my backpacking routine but you’re right! Thank you for all of your information. I’ve gone to your site more than any others for your well thought out and solid advice. Thank you for sharing your expertise and your passion for the wilderness!

  6. Dogwood
    Dogwood says:

    I keep returning to this site because it is based on one who walks the talk after researching the talk. Another nicely researched and supported piece. Much appreciated.

  7. Patrick
    Patrick says:

    Thanks. Isn’t the overuse of filters and chemical tx an example of your quote “Disease mongering is a well documented phenomenon in healthcare”6 I grew up never filtering, enjoying the taste of streams, still do but filter for stagnant ponds, tarns or lakes. My hiking buddy never has, decades of long hikes mainly in NW and CA. He’s read that 10% of the population is susceptible to giardia, he’s not (also, seldom carries water, drinks sparingly from any source.)

    I’ve read that giardia in various concentrations can be found everyone, pristine lakes, streams, maybe there’s a high amount to cause illness in everyone, a low amount, no one?
    In the 70s filtering was unheard of, all of a sudden people had to filter everything everywhere, where did all these bugs come from.
    It would be good to estimate the probability of getting sick from a source but that depends on your immunity. My friend thinks it’s 0% chance for him, I guess it could be high for those who’ve never been exposed to unpurified water (which would develop immunity?)

    • Alan Dixon
      Alan Dixon says:

      Patrick, sorry for the delayed response. Your comment came in while I was in the midst of site upgrades.

      Yeah, I have talked “unofficially” with a number of backcountry biologists I’ve run into in the field. Most of those discussions have (again unofficially) indicated along your thought lines. BUT for many reasons, I cannot in anyway contradict what Park, Land Use, and other officials say about water safety and water treatment. What they say goes. Best, -alan

  8. Greg Bluemn
    Greg Bluemn says:

    What about the possible affects of hiking at high altitude? A symptom of altitude sickness can be loss of appetite. Can this also affect the thirst mechanism? You are always encouraged to drink plenty of fluids at high altitude….

    • Alan Dixon
      Alan Dixon says:

      Greg, good Q. But it’s yet another myth about hydration (geez there as so many!). See Institute for Altitude Medicine for this:

      “MYTH #4 – DRINKING EXTRA WATER WILL PROTECT YOU FROM ALTITUDE ILLNESS. Staying hydrated is important at altitude. Symptoms of dehydration are similar to AMS. In reality you only need an additional liter to a liter and a half of water at altitude. Too much water is harmful and can dilute your body’s sodium level (hyponatremia) causing weakness, confusion, seizures, and coma…”

      Sound familiar to the article? Best, -alan

      • Greg Bluemn
        Greg Bluemn says:

        I understand drinking water will not alleviate altitude sickness (drinking coca tea while in Peru doesn’t hurt tho…) My question is kind of the opposite:
        My question is can mild (and possibly not recognized) altitude sickness result in dehydration because you don’t feel like eating or drinking. As a result you may want to track how much you drink to make sure you are staying hydrated and possibly drink more water (not excessively) than you would by just relying on the thirst mechanism.

  9. Jason Attas
    Jason Attas says:

    VERY interesting article! Thank you for all your research and clinical citations. I think you’re certainly on the right track. The difficult variable for which to control in the Drink When Thirsty theory, the x-factor so to say, is when individuals FEEL thirsty. Regardless of the science, everyone is different. In some sense, it’s like instructing people to layer up when cold. Everyone has a different tolerance for being cold and that dictates what people carry in their packs and certainly impacts their pack weight. You touch on this with the “personal water needs” disclaimer, but I think it’s an important distinction.

    Generally speaking, I think you’re absolutely right that people in the outdoors carry more water than they need…but they generally carry more food and gear than they need, too. There’s a “just in case” element that responsible hikers and backpackers need to build into their pack system to stay safe on the trail. The trick for those interested in reducing pack weight would seem to be to add water to their list of gear to put on the chopping block.

    If I’m solo backpacking and only carrying the necessary equipment to drink at the next water source when I’m thirsty, and I have an accident on the trail in which I fall, twist my ankle, or otherwise get injured in one of those freak accidents that can occur in the backcountry, I might not be able to make it to the next water source! At that point, I could be in some trouble if I am not carrying an on-board water supply. Remember, too, water isn’t just for consumption, it can be a necessary resource in first aid/wound treatment. Water for first aid must be considered when determining how much water everyone needs to carry. My own personal estimate is a small, 500mml/16 oz bottle that is reserved for emergency use only; emergency consumption and emergency wound treatment.

    All in all, I think you are right; people carry too much water with them. The trick is to reduce the volume of water in your kit to keep your outdoor experience enjoyable, safe, and self-sustainable.

    Excellent work! See you on the trail.

    • Alan Dixon
      Alan Dixon says:

      All good points Jason. Your point is good about being more prudent with carrying water when solo, off trail, with limited water, and folks not likely to come by — better to be on the safe side. But as you likely know this is a very small small % of all trips. Most are on trails, with adequate water, and hikers likely to come by if you are injured or have a problem. Good hiking, -a

  10. Fred Bar
    Fred Bar says:

    You have to be careful with the following statement: “On a personal note, when following Drink When Thirsty I frequently do not carry any water with me in the field (Sierras, Appalachian Trail, etc.)” – This could influence someone to make a dangerous decision. You see, before the fires in the lower AT this Fall in NC, there was a drought. Many of the sources on the guide were completely dry, but this information was not out yet on the web. I still made the right decision to carry my almost 3 Liters which paid off when passing the signs that had a piece of paper attached reading “No water” or “no water from here until XYZ” on my 20 – 24 mile days during a 3 day / 2 night hike.

  11. Steve
    Steve says:

    Very informative post. Thank you for your research and references for this article. Interesting points on marketing around thirst to create more demand even if we actually do not need it. As you said on a prior response – “Thirst is a trigger so we don’t get dehydrated, not a indication that we are dehydrated” – in other words, listen to your body wisely.

      • Bruce Burkham (Nevada)
        Bruce Burkham (Nevada) says:

        Speaking to “scientific support” for validity of the sayings & rumors, I have a suggestion for research & references that I cannot site. I earned essentially a pre-med level BS in 1972 and heard/read of a US Army research into a sweat glands vs “heat stroke” project during the Vietnam war as follows:
        Soldiers from humid southern states could handle the humid conditions in the jungle better because they had maintained their full number of sweat glands they were born with. Whereas, soldiers from the far west IE drier areas were unable to cool themselves due to “dis-use” atrophy of a high percentage of the number of sweat glands that they had at birth.
        As I recall this opinion was based on a “sweat gland count,” which we duplicated with iodine & corn starch under a Saran Wrap cover to show presence of moisture. Dry stays red due to lacking moisture and sweat triggered blue showing starch and iodine interaction. Not sure of the militarys method for counting.
        The effiency of cooling by sweating being a variable for consideration in your discussion of hydration management if what I am trying to raise. Hoping someone reading this will find a reference to the US Army’s research.

      • Alan Dixon
        Alan Dixon says:

        Sorry for the late posting of your comment. I am just back in the US after two weeks in remote areas of country and with absolutely no internet whatsoever. Best, -alan

  12. Jon
    Jon says:

    Nice post! I have always thought I drank too much water. I found your post to be very informative. Also, you many want to trim your last sentence (“Drink When Thirsty, it’s been keeping humans well hydrated for millions of years”) from millions of years to 200,000 years. I don’t think humans are that old yet.

    Keep up the nice posts!

    • Alan Dixon
      Alan Dixon says:

      OK fair enuf Jon :-)
      I have amended it to “hominoids.” Oldest human genus (Homo) remains date back almost 2.8 million years. And “Lucy,” genus Australopithecus (non-Homo genus) dates back to 3.2 million years.

  13. says:

    Pretty nice post. I just came across your site and wanted to saythat I’ve really liked reading your blog posts. In any caseI’ll be subscribing to your feed and I hope you post again soon!

  14. says:

    gccsteve / I just came across this the other day after starting a bathroom complete tear out/remodel.I'd just like to say what a very well written, informative and humorous article this is.Well done and I hope you are finished with your project.

    • Alan Dixon
      Alan Dixon says:

      Thanks for the kind comments. And I’m glad you found the article useful. And yes I am done for the time being, and drinking less ;-). All the best, -Alan

  15. says:

    The suggestions you provided here are extremely useful. It had been such a fun surprise to see that awaiting me immediately i woke up today. They are often to the point and simple to learn. Warm regards for the clever ideas you’ve shared in this article.

    • Alan Dixon
      Alan Dixon says:

      Thanks for the kind comments! And sorry for the late reply. Just out of the backcountry with connectivity. All the best, -Alan

    • Alan Dixon
      Alan Dixon says:

      Ron, I like the squeeze. For about an ounce more you get a higher flow rate and less clogging. The higher flow rate is key since you can quickly drink water at the source with a lot less sucking and squeezing. Everybody I hike with has the squeeze. Have a good year hiking, -alan

  16. Dave Keltie
    Dave Keltie says:

    I usually am walking fast enough to sweat even when wearing only a baselayer in a Welsh winter. Will sweat output (not sure how this could be measured?) not affect need to drink regularly?

    • Alan Dixon
      Alan Dixon says:

      Dave, See the thirst mechanism at the end of this post. Your body is constantly monitoring water volume and electroylite levels in a very sophisticated way. If you sweat a lot, then your natural thirst will kick in sooner. But note that your initial thirst does not mean you are dehydrated. That thirst is your body’s natural way of telling you to drink so you don’t get dehydrated. Have a great year walking, -alan

  17. Knut Strøm
    Knut Strøm says:

    Very interesting and informative! There is definetely many sayings and rumors that are not true, or understood.
    But I have to add that the fact that there is no evidence for an assumption or myth, is not the same as it being false. Evidence based research goes both ways =)

    Coming from and living in Norway, I spend a lot of my time in the mountains during winter. There is one aspect that is not discussed above as far as i can see, and that is the impact cold conditions have on the natural thirst system. In my experience, when you are being cold over time and mainly have access to cold water, you drink less, and the symptoms of not being well enough hydrated are slightly different from the symptoms in the summer. Headache and reduced physical performance often shows first. That being said, there is no scientific evidence for that, only my experience and schooling. I former worked as a winter combat instructor for the norwegian armed forces, and I’m now a fourth year medical student. Our practice is to hydrate in the morning with both water and electrolytes, and then drink small amount of water often during the day. But i fully agree with the researchers on urine color, wich is a bad indicator. (Even though brown urine seldom is a good sign)

    Hopefully I’ll do my own research in this field later on =)

  18. Russell J
    Russell J says:

    Another very interesting and informative post. Common sense prevails! I’ve always thought the “if you’re thirsty, it’s too late” maxim made little sense.

  19. John D
    John D says:

    Hi, Alan

    I’ll admit to skimming this hugely informative post, so I apologise if my two anecdotes add nothing. The post is in my reading list, so I will get back to it.

    Firstly, the drink, drink, drink message is older than the sports drink boom. In 1990, in NZ, a man from Hawaii told me to drink a dozen cups of water a day. He said it was absolutely essential to drink that much to stay hydrated and to get rid of poisons.

    Second, cold weather in windy, desert conditions can be dangerous for those of us from damper climes. Descending the Grand Canyon in May, I felt no thirst at all. In Scotland, my skin feels wet when I sweat. This did not happen in the Grand Canyon so one warning sign was missing. Next morning, my urine was brown and I drank three pints of water and a pint of tea before my urine started to look healthy.

    Thank you for the post. It must have taken a lot of work to put together.

    • Alan Dixon
      Alan Dixon says:

      Thanks for the “Scottish,” wetter clime input John. For what it’s worth, some of the highest numbers of over-hydration cases also come from the Grand Canyon. Some of the references cited in my article are specific incident reports on this. Take care, -alan


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