How Much Water Do You Need Daily?

Find out how drinking water can help your body
water with a strawberry in it

Water may not be the most exciting beverage in a world of iced mocha cappuccinos, but you literally can’t live without it. So how much do you really need to drink in a day? Well, let’s dive into some numbers.

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The National Academies of Science, Engineering and Medicine recommends the following for daily fluid intake:

  • 125 ounces (3.7 liters) for men.
  • 91 ounces (2.7 liters) for women.

Here’s the thing, though: Consider those numbers a starting point. “Your size, metabolism, location, diet, physical activity and health all factor into how much water you need,” says preventive medicine specialist Roxanne B. Sukol, MD.

And the fluid you consume doesn’t all come out of a glass. You can expect about 20% of your daily fluid intake to come from water that’s in food.

That’s a lot of information to gulp down all at once, right? Well, here’s a drip-by-drip accounting.

How to determine your fluid needs

To determine how much water you need, Dr. Sukol suggests considering these four factors:

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  • Activity level: If you work out a lot or are moving all day long, drink more water.
  • Location: If you find yourself in a warmer climate or at higher altitudes, you’ll probably want to increase your water intake.
  • Metabolism: If you think you have a speedy metabolism and your body seems to need more fuel to keep its engines revved, you may want to take some extra sips during the day.
  • Size: The more you weigh, the more water your body tends to need.

But water demands are also like the stock market, with daily fluctuations that depend on:

  • Alcohol consumption: Alcohol is a diuretic that can make you dehydrated. Before you decide on a second cocktail, drink a glass of water to rehydrate yourself and replace fluids caused by alcohol-mediated losses.
  • Health: “We really worry when people are sick and they’re not getting a sufficient amount of liquids — especially if they are also losing fluids due to vomiting or diarrhea,” notes Dr. Sukol. If you have a fever, it’s a good idea to increase your daily quota of fluids by a few cups. Clear broth and gelatin also count as fluids.
  • Physical activity: Did you go for a sweat-inducing run? The more active you are, the more water you’ll need.
  • Weather: You’ll definitely need more water during a heatwave than a blizzard. Use your common sense. If you live in a dry climate or a dry home, it won’t hurt to drink a little more than the daily recommendation.

Signs you’re not drinking enough water

Even if you’re not thirsty, don’t assume you’re drinking enough water. Instead, take a peek at your urine, says Dr. Sukol. If it’s a pale yellow color, you’re right on track. If your urine is darker or has a strong odor, then you could probably use more fluids.

Other symptoms of mild to moderate dehydration might include:

  • Constipation.
  • Dizziness.
  • Dry mouth.
  • Fatigue.
  • Muscle cramps.

More severe dehydration constitutes a medical emergency that requires immediate attention. Severe dehydration can include the above symptoms as well as:

  • Abdominal pain.
  • Confusion.
  • Lethargy.

The benefits of drinking water

Water is sometimes considered a fourth macronutrient, joining the list with protein, fats and carbohydrates. It’s required for your body to function optimally. (Fast fact: Your body is 60% water.)

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“That’s why you need to make sure that you’re drinking enough water,” explains Dr. Sukol. “It’s also why people who are too sick to drink tend to get into further trouble.”

Drinking water can help your:

  • Blood: Water ensures that your blood is just the right consistency to carry oxygen- and nutrient-rich blood to the areas that need it, including your brain, heart, kidneys and muscles.
  • Digestive system: “Dehydration is an easily reversible cause of constipation,” notes Dr. Sukol.
  • Joints: Think of your joints like the gears of your car. They need to be well-lubricated to work and last.
  • Kidneys: Drinking adequate amounts of water can prevent kidney damage and disorders.
  • Skin: For clear, wrinkle-free skin, drinking H2O can be just as effective as expensive anti-aging creams and lotions. It can also stave off certain skin disorders.
  • Teeth: Water keeps your mouth clean and lowers your risk for tooth decay.

There’s also research that consuming water may boost exercise performance, help with weight loss and reduce allergy and asthma symptoms.

Can you drink too much water?

The short answer is yes… but it’s hard to do. Hyponatremia, or low sodium, can be caused by a number of things — but one of them is when people drink too much water over a relatively short period of time.

“This condition can be quite serious but it is extremely rare,” says Dr. Sukol. “It’s pretty unusual that anyone would drink so much water that they would actually hurt themselves.”

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