While the common “8 glasses per day” rule is a general guide, daily water needs vary depending on factors such as age, sex, activity level, and diet. Your total hydration also includes fluids from other drinks and water-rich foods.

Jump to Key Takeaways.

Recommended Water Intake by Age

There is no exact amount of water for each age group, but there are general guidelines for moderate exercise and temperature.

  • Infants: Experts do not recommend water for infants before 6 months of age. Between 6 and 12 months of age, 1/2 cup to 1 cup (4 to 8 ounces) is recommended.
  • Children: One cup to 5 cups of water is recommended for children, along with 2 to 3 cups of milk.
  • Adolescents: Seven to 8 cups of water is recommended for adolescents.
  • Adults: Total water needs are estimated at 15.5 cups (3.7 liters) for adult males and 11.5 cups (2.7 liters) for adult females. This includes water from all sources—plain water, water in other beverages, and water in foods.
  • Pregnancy: According to the American College of Obstetricians and Gynecologists (ACOG), you need to drink 8–12 cups (64–96 ounces) of water daily during pregnancy. This amount is in addition to water from foods and other beverages.
  • Breastfeeding: To compensate for the extra water used to make breast milk, 16 cups of water are recommended daily, which can come from food, beverages, and drinking water.
  • Older adults: The National Academy of Medicine suggests an adequate intake of about 13 cups of daily fluids for males and 9 cups for females aged 51 and older. With a higher risk of dehydration and health issues, getting enough water is essential for older adults.

How Exercise Affects Your Hydration Needs

Whether you exercise for recreation or you’re an athlete, proper hydration is important for performance and overall health. Water regulates body temperature and lubricates your joints. It helps transport nutrients to give you energy and keep you healthy.

The American Council on Exercise has suggested the following basic guidelines for drinking water before, during, and after exercise:

  • Drink 17 to 20 ounces of water two to three hours before exercising.
  • Drink 8 ounces of water 20 to 30 minutes before starting to exercise or during your warm-up.
  • Drink 7 to 10 ounces of water every 10 to 20 minutes during exercise.
  • Drink 8 ounces of water no more than 30 minutes after you stop exercising.

If you exercise regularly, especially in the heat, hydration is essential. Here’s how to manage your water and electrolyte intake:

  • Hydration: Both larger, less frequent servings and smaller, more frequent sips can effectively maintain hydration during intense exercise.
  • Electrolytes: For short workouts, water is usually sufficient to stay hydrated. For long or intense workouts (longer than 60–90 minutes), consider electrolyte drinks to support muscle and organ function for optimal performance.
  • Sports drink recommendations: Choose drinks that include both carbohydrates and electrolytes. Hypotonic sport drinks, which are lower in sugar and salt, may provide the most significant hydration benefit.

Additional Factors that Affect Water Needs

While recommended daily intakes based on age and activity are helpful, additional factors affect how much water one needs.

Factors that impact water requirements include:

  • Body size
  • Sweat rate
  • The heat and humidity in your environment
  • Your clothing
  • How long and hard you are exercising

You also may need more water if you:

  • Live or work in a hot climate
  • Are physically active and sweat a lot
  • Have a fever, diarrhea, or vomiting
  • Are pregnant or breastfeeding

It’s possible to get too much water if you have certain health conditions, such as:

  • Thyroid disease
  • Kidney or liver problems
  • Heart problems

With these conditions, water intake may need to be lowered or closely monitored.

If you’re taking medications that make you retain water, like nonsteroidal anti-inflammatory drugs (NSAIDs), opiate pain medications, and some antidepressants, you may need to decrease how much water you drink.

How Much Should You Drink Based on Your Weight?

Many online sources suggest calculating daily water intake based on weight, such as drinking 0.5 to 1 ounce of water per pound you weigh. However, there is no universally accepted formula to measure the amount of water you should drink based on weight. Too many factors affect individual needs, including foods you eat, activity level, and overall health.

The best way to check if you’re drinking enough is to track your urine output and look for a pale yellow color with no odor. That indicates you’re well-hydrated.

Health Benefits of Drinking Water

Maintaining proper amounts of water in the body is critical for normal physiological functions. In infants, water accounts for about 80% of body weight. That decreases to about 60% in adult men and 50% in adult women.

Replenishing water in the body is key to meeting many biological needs such as:

  • Regulating body temperature and blood pressure
  • Lubricating and cushioning your joints
  • Protecting your spine and other body tissues
  • Ridding the body of waste through sweat, urine, and bowel movements
  • Preventing urinary tract infections, kidney stones, and constipation
  • Maintaining healthy skin
  • Supporting body functions such as neurological function, digestion, and kidney function.

Other Ways to Stay Hydrated

There are many other beverages besides water to help you stay hydrated.

Best choice beverages include:

  • Low- or no-calorie beverages such as plain coffee, plain tea, sparkling or seltzer water, and flavored waters
  • Drinks with calories and other essential nutrients, such as dairy and fortified nondairy milk, 100% fruit and vegetable juices, or smoothies

Other fluids that can help you stay hydrated, but should be limited, include:

  • Sugar-sweetened beverages, such as soda and fruit drinks
  • Caffeinated drinks such as energy drinks, as well as coffees, and teas with added milk and sweeteners
  • Drinks with sugar alternatives
  • Sports drinks

Sports drinks generally contain carbohydrates, electrolytes, and vitamins. Research indicates that sports drinks may benefit people engaged in vigorous exercise for more than one hour, especially if they are sweating heavily. For most people, regular water is sufficient to stay hydrated during exercise.

Preventing Dehydration

People lose (and must replace) water throughout the day from sweating, breathing, urinating, and having bowel movements. For healthy people, the vasopressin hormone (also called the antidiuretic hormone) and the kidneys help to balance fluid loss.

If you are regularly drinking water or consuming foods and beverages that replenish the water in your body, you should be able to maintain healthy levels of hydration. Without that constant replenishing, though, you can become dehydrated,

Signs of dehydration include:

  • Excessive thirst
  • Dry mouth, eyes, or skin
  • Headaches or cognitive impairment
  • Confusion, dizziness, or irritability
  • Lack of urination or constipation
  • Fatigue
  • Dry skin

Can You Drink Too Much Water?

Although drinking too much water is uncommon in healthy adults, occasionally overhydration can occur in athletes, people with kidney problems, or people taking certain medications that can cause excessive thirst.

Drinking too much water makes it hard for the kidneys to get rid of the excess water. The sodium content of your blood becomes diluted, and cells in the brain and other parts of the body swell with water. This is called hyponatremia, and it can be life-threatening.

Key Takeaways

  • The daily water intake required to stay hydrated can vary depending on your needs, health conditions, and lifestyle. In addition to drinking plain water, you can also consume water and fluids through foods and other beverages.
  • For healthy adults, optimal total fluid intake is estimated to be about 15 cups for men and 11 cups for women.
  • If you live or work in a hot climate or exercise and sweat a lot, consider increasing the number of glasses of water you drink daily.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. Harvard T.H. Chan School of Public Health. Water.

  2. Centers for Disease Control and Prevention. Water and healthier drinks.

  3. American Academy of Pediatrics. Recommended drinks for children age 5 & under.

  4. American Academy of Pediatrics. Choose water for healthy hydration.

  5. U.S. National Academies of Sciences, Engineering, and Medicine. Dietary reference intakes for electrolytes and water.

  6. American College of Obstetricians and Gynecologists. How much water should I drink during pregnancy?

  7. Academy of Nutrition and Dietetics. Nursing Your Baby? What You Eat and Drink Matters.

  8. American Academy of Family Physicians. Hydration for athletes.

  9. American Council on Exercise. Healthy hydration.

  10. Pryor RR, Larson JR, Vandermark LW, et al. Water consumption patterns impact hydration markers in males working in accordance with the National Institute for Occupational Safety and Health recommendations. J Occup Environ Hyg. 2023 Sep;20(9):414-425. doi: 10.1080/15459624.2023.2221713

  11. Johns Hopkins Medicine. Sports and hydration for athletes: Q & A with a dietitian.

  12. American Council on Exercise. Electrolytes: understanding replacement options.

  13. Rowlands DS, Kopetschny BH, Badenhorst CE. The Hydrating Effects of Hypertonic, Isotonic and Hypotonic Sports Drinks and Waters on Central Hydration During Continuous Exercise: A Systematic Meta-Analysis and Perspective. Sports Med. 2022 Feb;52(2):349-375. doi: 10.1007/s40279-021-01558-y

  14. Harvard Medical School. How much water should you drink?

  15. Academy of Nutrition and Dietetics. How Much Water Should You Drink?

  16. Lu H, Ayers E, Patel P, Mattoo TK. Body water percentage from childhood to old age. Kidney Res Clin Pract. 2023;42(3):340-348. doi:10.23876/j.krcp.22.062

  17. Popkin BM, D’Anci KE, Rosenberg IH. Water, hydration and health. Nutr Rev. 2010;68(8):439-458. doi: 10.1111/j.1753-4887.2010.00304.x

  18. Pound CM, Blair B, Canadian Paediatric Society, Nutrition and Gastroenterology Committee, Ottawa, Ontario, et al. Energy and sports drinks in children and adolescents. Paediatrics & Child Health. 2017;22(7):406-410. doi: 10.1093/pch/pxx132

  19. Liska D, Mah E, Brisbois T, Barrios PL, Baker LB, Spriet LL. Narrative review of hydration and selected health outcomes in the general population. Nutrients. 2019;11(1):70. doi: 10.3390/nu11010070

  20. MSD Manual Consumer Version. Overhydration.

Rebecca Valdez RDN Headshot

By Rebecca Valdez, MS, RDN

Valdez is a registered dietitian nutritionist, health writer, and nutrition consultant. She received her MS degree in nutrition from Columbia University.

Thanks for your feedback!

What is your feedback?

Helpful

Report an Error

Other