Myth: Dehydration is uncomfortable, but not dangerous.
Fact: While most of us will only ever experience mild dehydration symptoms like headache, sluggishness or decreased urine or sweat output, it can become severe and require medical attention. Serious complications include swelling of the brain, seizures, kidney failure and even death, according to the Mayo Clinic.
Fortunately, adults can usually nip mild or moderate dehydration in the bud with some extra fluid, according to the Mayo Clinic. But when not attended to in early stages, adults may develop extreme thirst, dizziness and confusion, and stop urinating. Symptoms should be taken even more seriously in children and older adults, according to the Mayo Clinic, especially diarrhea, vomiting, fever, inability to keep fluids down, irritability or confusion.
Myth: If you're thirsty, you're already dehydrated.
Fact: It's not too late. In fact, thirst is the body's way of telling you to drink water, and you're not at risk of becoming dangerously dehydrated the minute you feel a little parched. "When you get thirsty, the deficit of water in your body is trivial -- it's a very sensitive gauge," Dr. Stanley Goldfarb, professor of medicine at the University of Pennsylvania, told NBC in January. "It might be only a 1 percent reduction in your overall water. And it just requires drinking some fluid."
In fact, drinking when you're thirsty (sounds pretty basic, right?) is a pretty fail-proof method of staying hydrated, says Dr. Timothy Noakes, professor of exercise and sports science at the University of Cape Town in South Africa and author of Waterlogged. "You don't tell your dog or your cat when to drink, they've got a thirst mechanism," he told NBC. "Why should it be that humans should be the unique animal in the world who have to be told when to drink?"
He attributes this "you're doing it wrong" attitude largely to the bottled-water and sports drink industries. "Commercialization and industrialization have told us that humans are weak," he says, when in reality our ability to run in the heat helped us outsmart our ancient predators like lions and tigers, he says. "We should never have survived, and suddenly we're told no one knows when to drink?"
Myth: Everyone needs to drink eight glasses of water a day.
Fact: This general rule of thumb is outdated, propagated today mostly by bottled water companies. So how much do you really need to drink?
The Institute of Medicine (IOM) recommends men get roughly three liters of total beverage intake every day, and women get 2.2 liters, while others say there's no need to force water consumption if you're not thirsty.
Keep in mind those suggested intake levels include more than just water alone, says Noakes. "What you should say is glasses of fluid a day," he says, remembering to sip additional liquids the more you exercise. Coffee, tea, fruit juices, even sweetened beverages provide your body with more water -- although we wouldn't recommend the latter for hydration purposes or much of anything, really. Even food counts. About 20 percent of the average person's water intake comes from food, according to the IOM, especially from foods with high water content, like watermelon and cucumbers.
At the end of the day, how much water you should drink is extremely personal: whatever quenches your thirst.
Myth: Clear urine is a sure sign of hydration.
Fact: While keeping an eye on your urine output maybe isn't the most pleasant summer activity, it really can provide a measure of how hydrated (or dehydrated) you are, essentially in real time. But it's not clear urine that you're looking for, but rather a pale yellow. Lawrence Armstrong, Ph.D., an exercise physiologist and professor at the University of Connecticut's Human Performance Laboratory, established a urine color chart to model a measure of dehydration. Based on where you fall on the chart, you can adjust your fluid intake accordingly, the New York Times reported. (Keep in mind that certain supplements -- and foods -- can change the color of your urine.)
Fact: Overhydrating can be extremely dangerous -- but it's relatively rare.
Drinking too much water leads to what's called hyponatremia, when levels of sodium in the body are so diluted that the cells begin to swell, according to the Mayo Clinic. Symptoms usually include nausea, vomiting, headache, confusion and fatigue, and can escalate to seizures and coma.
That doesn't mean don't drink when you're thirsty! It truly takes guzzling copious amounts to cause so-called water-intoxication. That's why refueling marathon runners, for example, are some of the more common hyponatremia sufferers. Of the estimated 2,600 cases of hyponatremia that have resulted in hospitalization that Noakes is aware of, he says there's "no reason they should have gotten sick." We only get ourselves into trouble when we drink beyond our thirst, he says, whether that's because of out-of-date advice or a sports drink commercial.
If you're still worried, consider this rule of thumb: Try not to drink to the point where you feel full from water alone, the Mayo Clinic reported.
Myth: Exercisers need sports drinks
Fact: If you're working out for less than an hour, water will do just fine. You don't deplete electrolyte and glycogen reserves until you've been exercising intensely for over an hour. Endurance athletes can benefit from the right mix of sugar (read: energy) and sodium, although today's sports drinks, with their miles-long ingredients list full of impossible-to-pronounce artificial additives may not necessarily be the smartest pick.
Instead, make your own! Or try some of these foods that can act as a natural alternative to sports drinks. Or consider forgoing it altogether. Many of us eat a diet so high in carbohydrates and sodium already that "replenishing" with an electrolyte drink after today's workout may just mean excreting it tomorrow, says Noakes.
Myth: Coffee dehydrates you.
Fact: Only if you overdo it. While caffeine is dehydrating, the water in coffee (and tea, for that matter) more than makes up for the effects, ultimately leaving you more hydrated than you were, pre-java. According to the Mayo Clinic, consuming 500 or more milligrams of caffeine a day -- somewhere around five cups of coffee -- could put you at risk for dehydration, but let's all agree to know when to say when.
This summer, stay hydrated but avoid over-consumption. Anything in excess can be bad for you.