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 out there (iced horchata latte, anyone?), but you literally can’t live without it. So how much do you really need to drink in a day? Well, it depends on a number of variables.

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“Your size, activity, metabolism, location, diet, physical activity and health all factor into how much water you need,” says preventive medicine specialist Roxanne Sukol, MD. But before you throw up your hands in frustration (that’s a lot to consider!), Dr. Sukol explains how you can make sure that you’re adequately hydrated.

How to determine your recommended daily water intake

The National Academies of Science, Engineering and Medicine recommends that men drink about 3.7 liters (about 125 ounces) a day and women drink 2.7 liters (about 91 ounces). “Those amounts include the water that’s in our food,” says Dr. Sukol. “So it doesn’t mean that you have to drink that many ounces of water. The water in food also counts.”

Dr. Sukol suggests considering these four factors when determining your water needs:

  • 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, you’ll probably want to increase your water intake.
  • Metabolism: If you consider yourself to have a faster metabolism, and your body seems to need more fuel to keep its engines revved — you may also notice that you need more water.
  • Size: The more you weigh, the more water your body tends to need.

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

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  • Alcohol consumption: 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 or did you decide to snuggle up with a book? Again, 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.

How to tell if you’re drinking enough water

Even if you’re not thirsty, don’t assume you’re drinking enough water. Instead, take a peek at your urine. “If it’s almost the color of water, you’re right on track. But if your urine is bright yellow or has a strong odor, then you could probably use more fluids,” notes Dr. Sukol.

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, and can include any or all of these as well as:

  • Abdominal pain.
  • Confusion.
  • Lethargy.

The benefits of drinking water

The human body is 60% water — and our blood is 90% water. “That’s why you need to make sure that you’re drinking enough water. It’s also why people who are too sick to drink can tend to get into further trouble,” explains Dr. Sukol. “In addition to protein, fats and carbohydrates, water is sometimes considered a fourth macronutrient: needed for our body to function optimally.”

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For example, water helps 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.”
  • 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, 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 water may:

  • Boost exercise performance.
  • Help with weight loss.
  • Reduce allergy and asthma symptoms.

Can you drink too much water?

The short answer: 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 much too much water over a relatively short time period,” says Dr. Sukol. “but it’s pretty unusual that anyone would drink so much water that they would actually hurt themselves. This condition can be quite serious but it is extremely rare.”

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