How Much Water Do You Need Daily?
The average American today has a ridiculous number of choices of beverages available to them by the shelf-full. From soda to fruit juice to sports drinks, nothing can replace good old water.
Though healthy in moderation, pure fruit juice essentially is water and sugar. In fact, 12 ounces of grape soda has 159 calories. The same amount of unsweetened grape juice packs 228 calories. Dr. David Ludwig at Children's Hospital Boston said recently. "Juice is only minimally better than soda."
When it comes to staying hydrated, water is your best choice. When you're in the wilderness, it will likely be your main source of hydration.
So How Much Water Does One Need?
How many glasses of water should you drink a day? It's a simple question with no easy answers. Studies have produced varying recommendations over the years, but in truth, your water needs depend on many factors, including your health, how active you are and where you live.
So how much fluid does the average, healthy adult living in a temperate climate need? The Institute of Medicine determined that an adequate intake (AI) for men is roughly 3 liters (about 13 cups) of total beverages a day. The AI for women is 2.2 liters (about 9 cups) of total beverages a day.
Everyone has heard the advice, "Drink eight 8-ounce glasses of water a day." That's about 1.9 liters, which isn't that different from the Institute of Medicine recommendations. Although the "8 by 8" rule isn't supported by hard evidence, it remains popular because it's easy to remember. Just keep in mind that the rule should be reframed as: "Drink at least eight 8-ounce glasses of fluid a day," because all fluids count toward the daily total.
As long as you are not taking riboflavin (vitamin B2; also found in most multi-vitamins), which fluoresces and turns your urine bright yellow, then your urine should be a very light-colored yellow. If it is a deep, dark yellow then you are likely not drinking enough water. If your urine is scant or if you haven't urinated in several hours, that too is an indication that you're not drinking enough. (Based on the results from a few different studies, a healthy person urinates on average about seven or eight times a day.)
Keep in mind that as you get older your thirst mechanism tends to work less efficiently, so older adults will want to be sure to drink water regularly, and again make sure your urine is a light, pale color.
Recent studies have shown that all hydration does not need to come from fluids. Up to 20 percent of a person's daily intake can come from food sources such as soup, watermelon, spinach and more.
How Long Can You Live Without Water?
“I have sort of a 100-hour rule," says Dr. Claude Piantadosi of Duke University in North Carolina. "Depending on the temperature you are exposed to, you can go 100 hours without drinking at an average temperature outdoors. If it’s cooler, you can go a little longer. If you are exposed to direct sunlight, it’s less," he added.
"One week is about the maximum people can last with no water at all – and if it’s hot, or dry, or if people are moving around, they can die of dehydration much more quickly." (If you'd like to learn the symptoms, prevention, and treatment of dehydration, please see our Outdoor Health Emergencies page)
“The more energy you expend the more likely you are to lose water,” Randall Packer, an expert on the body’s water balance at George Washington University says. “You lose a little bit of water every time you exhale. You lose water when you sweat. You do make a little water when you metabolize food … but the balance is such that you always need some sort of water intake.”
Dehydration kills by bringing blood pressure down to fatal levels, Packer says.
“Under extreme conditions an adult can lose 1 to 1.5 liters of sweat per hour. If that loss is not replaced by drinking, the total volume of body fluid can fall quickly and, most dangerously, blood volume drops,” Packer says.
Also, six weeks without food is about the limit for an average weight person. Dr. Claude Piantadosi says, "If somebody's really huge, really fat, they could live longer than six weeks."
Water is the best fluid for survival, but it’s not the only one, he noted. “A person can stay hydrated by drinking many different kinds of fluids in addition to water, with one exception. Drinking alcoholic beverages actually causes dehydration,” Packer says.
“Ethanol depresses the level of anti-diuretic hormone, increasing urine volume to the extent where more fluid is lost in urine than is gained in the drink.”
Credit For Content:
The Beverage Institute For Health and Wellness