How Much Water You Need to Drink

Medically reviewed by Stacy Sampson, DO on April 19, 2017Written by Ashley Marcin

Overview

You may have heard that you should aim to drink eight 8-ounce glasses of water per day. How much you should actually drink is more individualized than you might think. The Institute of Medicine (IOM) currently recommends that men should drink at least 104 ounces of water per day, which is 13 cups. They say women should drink at least 72 ounces, which is 9 cups. Even still, the answer to exactly how much water you should drink isn’t so simple.

Water recommendations

While the eight glasses rule is a good start, it isn’t based on solid, well-researched information. Your body weight is made up of 60 percent water. Every system in your body needs water to function. Your recommended intake is based on factors including your sex, age, activity level, and others, such as if you’re pregnant or breastfeeding.

Adults

The current IOM recommendation for people ages 19 and older is around 3.7 liters for men and 2.7 liters for women. This is your overall fluid intake per day, including anything you eat or drink containing water in it, like fruits or vegetables.

Of this total, men should drink around 13 cups from beverages. For women, it’s 9 cups.

Children

Recommendations for kids have a lot to do with age. Girls and boys between ages 4 and 8 years should drink 40 ounces per day, or five cups. This amount increases to 56 to 64 ounces, or 7 to 8 cups, by ages 9 to 13 years. For ages 14 to 18, the recommended water intake is 64 to 88 ounces, or 8 to 11 cups.

Women of reproductive age

If you’re pregnant or breastfeeding, your recommendations change. Pregnant women of all ages should aim to get 80 ounces, or ten 8-ounce glasses of water each day. Breastfeeding women may need to up their total water intake to 104 ounces, or 13 cups.

DemographicDaily recommended amount of water (from drinks)
children 4–8 years old5 cups, or 40 total ounces
children 9–13 years old7–8 cups, or 56–64 total ounces
children 14–18 years old8–11 cups, or 64–88 total ounces
men, 19 years and older13 cups, or 104 total ounces
women, 19 years and older9 cups, or 72 total ounces
pregnant women10 cups, or 80 total ounces
breastfeeding women13 cups, or 104 total ounces

Other considerations

You may also need to drink more water if you live in a hot climate, exercise often, or have a fever, diarrhea, or vomiting.

  • Add an additional 1.5 to 2.5 cups of water each day if you exercise. You may need to add even more if you work out for longer than an hour.
  • You may need more water if you live in a hot climate.
  • If you live at an elevation greater than 8,200 feet above sea level, you may also need to drink more.
  • When you have a fever, vomiting, or diarrhea, your body loses more fluids than usual, so drink more water. Your doctor may even suggest adding drinks with electrolytes to keep your electrolyte balance more stable.

Why do you need water?

Water is important for most processes your body goes through in a day. When you drink water, you replenish your stores. Without enough water, your body and its organs can’t function properly.

Benefits of drinking water include:

  • keeping your body temperature within a normal range
  • lubricating and cushioning your joints
  • protecting your spine and other tissues
  • helping you eliminate waste through urine, sweat, and bowel movements

Drinking enough water can also help you look your best. For example, water keeps your skin looking healthy. Skin is your body’s largest organ. When you drink plenty of water, you keep it healthy and hydrated. And because water contains zero calories, water can be an excellent tool for managing your weight, as well.

Risks

There are risks of drinking too little or too much water.

Dehydration

Your body is constantly using and losing fluids through actions like sweating and urinating. Dehydration happens when your body loses more water or fluid than it takes in.

Symptoms of dehydration can range from being extremely thirsty to feeling fatigued. You may also notice you aren’t urinating as frequently or that your urine is dark. In children, dehydration may cause a dry mouth and tongue, lack of tears while crying, and fewer wet diapers than usual.

Dehydration may lead to:

Mild dehydration may be treated by drinking more water and other fluids. If you have severe dehydration, you may need treatment at the hospital. Your doctor will likely give you intravenous (IV) fluids and salts until your symptoms go away.

Hyponatremia

Drinking too much water may be dangerous to your health as well. When you drink too much, the extra water can dilute the electrolytes in your blood. Your sodium levels decrease and can lead to what is called hyponatremia.

Symptoms include:

Water intoxication hyponatremia is uncommon. People with a smaller build and children are at a higher risk of developing this condition. So are active people, like marathon runners, who drink large quantities of water in a short period of time. If you may be at risk due to drinking large quantities of water for exercise, consider drinking a sports drink that contains sodium and other electrolytes to help replenish the electrolytes you lose through sweating.

Learn more: How to prevent an electrolyte imbalance »

Takeaway

Staying hydrated goes beyond just the water you drink. Foods make up around 20 percent of your total fluid requirements each day. Along with drinking your 9 to 13 daily cups of water, try to eat lots of fruits and vegetables.

Some foods with high water content include:

Tips for drinking enough water

You may be able to meet your water intake goal by drinking when you are thirsty and with your meals. If you need some extra help consuming enough water, check out these tips for drinking more:

  • Try carrying a water bottle with you wherever you go, including around the office, at the gym, and even on road trips.
  • Focus on fluids. You don’t have to drink plain water to meet your hydration needs. Other good sources of fluid include milk, pure fruit juices, tea, and broth.
  • Skip sugary drinks. While you can get fluid from soda, juice, and alcohol, these beverages have high calorie contents. It’s still smart to choose water whenever possible.
  • Drink water while out to eat. Drink a glass of water instead of ordering another beverage. You can save some cash and lower the total calories of your meal, too.
  • Add some flair to your water by squeezing in fresh lemon or lime juice.
  • If you’re working out hard, consider drinking a sports drink that has electrolytes to help replace the ones you lose through sweating.
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