Out on the Mojave, and throughout the desert Southwest, it can be very dry.  You are probably on your way to someplace else - like Death Valley or Zion or Grand Canyon, where you will want to be physically active - at least a little.  Don't arrive dehydrated - and be especially careful when exerting yourself in the arid Southwest.   The Mojave, which includes Death Valley, is one of the hottest and driest places on earth.

Many people don't know to drink enough water.   Nurses, teachers, physicians, firefighters and many others are trained to drink their minimum 64 ounces a day, or to oversee children in drinking enough water, but still, many people in North America are underhydrated.  Vertigo, stumbling about, and inattention are not good states when one is visiting Grand Canyon or hiking up Angels Landing.  People have been known to suffer from mild to moderate dehydration with a bottle of water in the car next to them.  Children and the elderly are more vulnerable than others - but physical conditioning itself doesn't protect you from dehydration.  

It isn't just a matter of your own safety - your dehydration can affect your driving, and it can endanger others.

Staying hydrated is also essential to avoiding heat exhaustion.  Many people suffer from heat exhaustion without realizing it.  This article is about dehydration - not heat exhaustion.

The early stages of dehydration have no symptoms.  Indeed you may feel quite well, you might even have an endorphin rush.

When you're excited or on that endorphin rush, you aren't as likely to feel thirsty.

Dehydration alone does not cause your body temperature to raise.  

Here's some basic information on dehydration (the subject of this article), with its accompanying problem - heat exhaustion (which deserves its own article).

Thirst is not an indicator of whether you are well-hydrated or not, that's why so many people are chronically underhydrated.  You probably already know that coffee, tea, sodas and beer are not sufficient to keep yourself hydrated.  But, do they count at all as hydration?  Of course, although every time you drink a caffeinated beverage or a salt containing beverage or an alcoholic beverage, you increase your basic daily requirement of water. 

But what is that daily basic requirement?

The standard answer has been 64 ounces a day (half a gallon) per average adult, more for children, and more for active people.  But that's based on a weight of approximately 120 pounds.  So how do you know how much you personally are supposed to drink?  There's a pretty well defined formula. 

However,  if you want a faster answer, there is a handy online calculator.

Actually, there are several of these calculators - most of them put together by medical professionals who see dehydration cases and/or like to fiddle with making computer gadgets.  They put this work into them for a reason.

A 150 pound person in arid hot conditions, who hikes for 20 minutes or changes a tire, needs about 90 ounces of water a day.  If you are in an occupation where you move around a lot - you're not just sitting there in your car - you'll need more.  If you are just sitting in your car with the A/C on, you still need to consider the overall humidity of your environment.

Now, an additional thing to consider is that  it's clear that some people who eat diets really high in naturally fluid-containing foods, like fruits and vegetables and soups, don't need as many ounces in a day.  In other words, that beer does count for something in terms of getting water into your body.    But, if you are responsible for a child or baby, or an elderly person - or you yourself are overweight, or you are very active, you need to make sure you really are getting enough water.

What happens when you don't?

Well, the first thing is that you won't necessarily notice.

Aside from increasingly your chance of heat exhaustion (or, in dire cases, heat stroke), what does dehydration do to you?  Is it really that bad? That depends on your point of view.  

Even mild dehydration can cause can reduce muscle performance.

This can mean that one foot doesn't lift quite as much as it usually does - and you trip.  Or you don't react as quickly as you usually do.  Not a big deal in most circumstances - but for those who want optimal performance from their bodies, it's not a good thing.

Dehydration reduces alertness.

Not good when driving long distances.   Dehydration also reduces reaction time as much as 12% (see the link just above).  That makes it similar to drinking and driving - which isn't a bad way to view it.  It can feel fun, remember, as your body pumps out adrenalin and endorphins to help you respond to what your body thinks is a stressed environment - but it isn't fun for other people when you drive over the line into their line or for you, if you get into an accident.

You're more likely to get a virus when you're dehydrated.

So if you're the type that worries about H1N1 and things like that - stay hydrated.

What is mild dehydration?  Being down about a liter - about 30 ounces - in terms of hydration.  So while people can and do get by on just 24-32 ounces of water a day - even in the Gobi desert - they will not be performing at their optimal level, in terms of muscle coordination.

But what else happens, with even mild dehydration?  Rangers at the hot national parks know that heart attacks, fainting, and disorientation happen.  But why is dehydration such a problem?

Your blood thickens.   This is one of the causes of the headache - a symptom that should not be ignored.   Don't just take a pill and ignore the underlying cause, if you're in a hot climate.  Headache means you have waited way too long to drink your water.  Dry eyes, nose bleeds, irritation to throat tissue and lungs, muscle cramps - including in the intestines - are all symptoms.  Once you are even mildly dehydrated. your stomach and intestines are going to react differently to the inflow of the water you eventually decide to drink - you will need a couple of hours, or longer, to get over it.  If you just ignore it, as many people do, you will feel lousy the next day.  

The headache is likely caused by the dilation of blood vessels throughout your body  - which some people experience as a kind of rush - but which, in your brain, can eventually cause migraine-like symptoms. Or migraines.

If you are on any sort of medication, the concentrations of it in your bloodstream change - and may not circulate as well.

There are some conditions (like fibromyalgia, multiple sclerosis and others) that are specifically made worse by dehydration.

In older people, orthostatic hypotension can be due to even mild dehydration and will increase in hot dry weather, leading to dizziness and unstableness.   In fact, it's pretty common.

Not everyone experiences cognitive symptoms with dehydration, but most do.

It's like the effects of many other things on the human body - it's individual.  It's possible that some people begin to produce more adrenalin and therefore feel a bit sharper than they usually do.  They may also feel more irritable.  This is the body's way of telling you to quest for more water.  But, there are ample studies that show that for many people, dehydration alone can lead to bad decision making and worsened performance on tasks.

How to rehydrate if you get a little dehydrated:

If you notice you're not peeing regularly (every two hours) or your pee is dark, you're pretty dehydrated already. 

Drink water, not caffeinated beverages or sodas.  Some soda is fine - it has salt, you need salt.  But drink water.

Drink 4-6 ounces at a time and drink frequently - like every 15-20 minutes.

Continue until you're back to peeing regularly - and your urine is relatively clear.

Eat a snack containing salt and calcium at a minimum; potassium, magnesium and some sort of protein aren't a bad idea either...a little at a time.

It turns out that most water is absorbed in the small intestine.  This means that gulping a lot of water immediately upon realizing you're dehydrated (or waiting until you are thirsty) can mean that there's a time lapse before you get the water absorbed into your bloodstream.  

Sipping teensy bits of water isn't a great idea, either.  

That's because it just wets the stomach lining - which absorbs it, but it doesn't get to your blood stream.  So take a reasonable amount - about 4-6 ounces - at a time.  Kids sometimes have a hard time with this.  It's also a fact that kids don't like warm water - and some don't like water at all.  Juices and other drinks are better than no fluid at all, but diluting them with water is a good idea.  Special rehydration drinks aren't usually necessary for a person with an ordinary diet, but sometimes they make drinking water more fun.  If vitamin water or propel is what your kids will drink, use it.  Cooler water hydrates you faster than warmer water.

Air conditioning alone does not prevent dehydration.

Drinking cool water is better than drinking warm water, though - in terms of doing its job of hydrating you.  

A person who weighs 200 pounds who has been active for a mere 40 minutes in high temperatures does indeed need about 120 ounces of water - about a gallon.

A person who weighs more - and many do - need more than that.

You're probably going to survive a day or two of dehydration, in any case.  But your ability to handle the other effects of heat will be diminished.  Most people do not want to stress their bodies in this way, but people who like extreme athletics in hot weather clearly wish to stress their bodies more than others may want to.  Unless dehydration is chronic, you probably are going to survive it just fine.  You might not feel as well as you usually do - and you'll probably attribute that to the heat.  But not feeling well means you might not be driving well.

And, you may be endangering others with your dehydration.

What about electrolytes?

If you've been reading the links in this article, you already know about electrolytes - sodium, calcium, potassium and other ions your body needs to survive.  If you are dehydrated, you need to drink water, but you also need salt, calcium and potassium.  Some say you also need magnesium.  Trail mix contains most of these things, so do any number of other snacks.  But if you're dehydrated, you may not feel hungry - so making yourself eat crackers and cheese is a good idea.  Having crackers and cheese (or anything similar that you like) is quite a good idea in the desert.

Don't overdo the water, of course - just up your usual intake, and try to make sure you really are hydrated before you travel.  

This isn't true just for deserts - airplanes are notorious for dehydrating.  The more water you drink, the more salt you will need, as well.  If you are preconditioned and properly hydrated (a normal person is drinking at least 60 ounces of water a day - and is allowing themselves a concomittant amount of salt), you will easily be able to eat a couple more crackers and a slice of cheese to keep up.

If you're exerting yourself a lot - see the firefighters' advice in the section on exertion, below.

Precondition yourself for heat and airplane travel.

If you aren't in the habit of drinking enough to begin with, change that habit and get yourself used to the feeling of actually being hydrated.  Over the long term, your kidneys will thank you - and so will the rest of your body.  Everything about hydration applies to airplane travel as well.

Preconditioning oneself to heat, by itself, is a good idea - people who routinely use saunas, or turn off the air conditioning when driving their daily commute or who work outside in the hot part of the day are more likely to do well at staying hydrated in desert heat.

Small children need extra care.

Infants, in particular, need to be hydrated.  Signs of dehydration in children are the same as in grown-ups - their urine is darker than usual.  Diaper-babies are therefore easier to keep track of than the newly potty-trained, so you might want to remember to check - for real - how they are doing, because they often don't complain of symptoms until dehydration is well under way.  You don't want them more susceptible to viruses while traveling.

Taking extra water along on the trip doesn't hurt anyone.

While some members of your travel party may need only half a gallon a day, some may need more.  In addition, people may want to rinse their faces and hands, or use a mister to try and keep cool.  Water evaporates out of containers, as well, and some containers leak.  Why cut it close?  Having enough water for one extra day when traveling in dry country can be very helpful - if there's a fire, a flood, or any other reason why water deliveries are cut off to those gas stations you stop at, you'll be very glad you have water.   If you're rerouted through an area that has only one gas station, in Arizona or Utah you may find there's no drinkable water at all at the gas stations - too many people going through (and yes, sometimes stations run out of gasoline to sell).  Most car radiators can use water as coolant if the need arises.  You wouldn't want to add only water - but if you're just topping off after a little blow-off, water is useful.  If you do have any roadside trouble, remember that your water needs will quickly soar beyond that 1/.2 gallon (or gallon) that you need every day, depending on your size and overall activity level.  

 What if you actually are hiking, exerting yourself, or otherwise actually active when it's hot and dry?

Sometimes it's necessary to exert oneself - what if you do run out of gas, or your tire blows out?  What then?  There's a guide for hydration for that situation .  It recommends 1 liter per hour of exertion.  So if you had to walk two hours to get somewhere after your rock hunting expedition was derailed by your car stradling a boulder you just didn't see in a gully, you need 2 more liters of water than you did before.  That's about half a gallon.  Haveenough water on hand that if one person has to go for help - for any reason - there's enough water for the people left behind - but there must be enough water for the walker.  

If you really are hiking in the heat, you need to know way more about electrolytes than can be covered here.

Obviously, having a backpack in the car is a good idea.   And finally, take enough water to be able to be a Good Samaritan, if need be.


Dehydration and kids.

Studies show that dehydration can increase vehicle accident rates, especially with motorcycles - but in extreme environments, with other vehicles as well.

112 ounces a day for an athlete...

 If you show up at the ER with fainting or dizziness, the doctor is going to be thinking...wonder if they have enough water?

 A lot of people are chronically dehydrated - and don't even know it.

 Is Heat getting the better of you?

Experiments show that being physically fit doesn't change your response to dehydration - this is one experiment.

Don't drink too much at one time - messes with your salt balance - thirst is helpful in deciding how much additional water to drink.

Once again, thirst is not a good way to tell if you're dehydrated.  2 gallons as a goal for desert trips.


This page is dedicated to first responders, emergency personnel, firefighters, nurse educators and others, in gratitude for all the work they do, and in memory of those died in the line of duty, and to their families.  It is also dedicated to the people who do go the extra mile to stop and help out fellow travelers in the desert, a dying breed.