We owe our lives to water.
No, really: Water is the driving force in everything we do — and it makes up 60 percent of our bodies. It lubricates joints, helps flush waste out of our organs and keeps our body temperature regulated.
And, contrary to what your friend who “never drinks water” says, you have to have it or you’ll die within a few days.
“You can go 100 hours without drinking at an average temperature outdoors,” Claude Piantadosi of Duke University told Fox. “If it’s cooler, you can go a little longer. If you are exposed to direct sunlight, it’s less.”
But one glass a day isn’t enough to keep our bodies quenched. So, how much water should you drink a day to keep your body in tip-top shape?
How much water should you drink a day?
The answer: It depends on a number of factors, including how much you sweat and the temperature outdoors.
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“Under extreme conditions an adult can lose 1 to 1.5 liters of sweat per hour,“ Randall K. Packer, a professor of biology at George Washington University, wrote in an article for Scientific American.
So does that mean we should be drinking an equal amount every hour? Not necessarily.
You’ve probably heard that you should be drinking 64 ounces of water a day (eight ounces of water, eight times a day). However, science shows that might actually be more than you need. So, how much water should you drink a day? The National Academies of Sciences suggest that women get a total of 2.7 liters (about 92 ounces) of water a day, while men need about 3.7 liters (about 128 ounces).
Wait, isn’t 92 and 128 more than 64? Yes, but that number takes into account water you get from foods (like produce and soups), along with the water in other beverages like coffee, soda and even beer. According to the National Academies of Sciences, we get about 20 percent of our daily water needs through our diets — and it counts.
Can you drink too much water?
Too much of a good thing usually ends up being a bad thing, and water is no exception.
Drinking more water in a short period of time can overload your kidneys and cause your body to dilute the electrolytes in your blood — especially sodium. When sodium drops below 135 mmol/L, your body experiences hyponatremia, or water intoxication, and can lead to brain disruption and even death.
The kidneys can eliminate anywhere from 5.3 to 7.4 gallons of water a day, but can’t process more than about 27 to 33 ounces per hour. Symptoms of hyponatremia (like headaches, nausea, vomiting, muscle weakness and confusion) can occur from drinking anywhere from three or four liters of water in a short period of time, like an hour.
And it does happen.
In 2007, a California woman died of hyponatremia after participating in a "Hold Your Wee for a Wii" contest. For the competition, contestants were instructed to drink as much water as possible without going to the bathroom and the person who held it the longest won the Nintendo game system. One of the contestants, Jennifer Lea Strange, died hours after drinking several eight-ounce bottles of water over a short period.
"She said to one of our supervisors that she was on her way home and her head was hurting her real bad," co-worker Laura Rios told the Los Angeles Times of Strange’s behavior before she was found dead at her home. "She was crying and that was the last that anyone had heard from her.”
To avoid hyponatremia symptoms, limit your water intake to about 27-33 ounces of water per hour.
The bottom line on water consumption
So, how much water should you drink a day? If you’re out in the sun working or playing sports all day, you should drink more water than someone sitting indoors.
And listen to your body — feeling thirsty is your body’s built-in dehydration detector.
“The vast majority of healthy people adequately meet their daily hydration needs by letting thirst be their guide,” advises the National Academy of Sciences.
You can also check your pee to get an idea of your hydration levels: Dark urine usually means you’re dehydrated, while clear or pale yellow means you’re well hydrated.