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Recommended Water Intake by Age

I am a writer sharing my own experiences and knowledge about how to stay healthy and live a happy life.

How much water do you really need?

How much water do you really need?

Why Water Is Essential for Health

Water is your body's most essential chemical substance. About 60% of human body weight is water and all of the body's processes depend on water. Water flushes out waste products from vital organs, carries essential nutrients around the body, and provides hydration for ear, nasal, and throat tissues.

Not enough water can result in dehydration, and even slight dehydration can decrease your energy, making you weak and tired. Some sources argue against needing eight glasses of water a day (Greenfield, 2011; Valtin, 2002), but most studies are in support of eight glasses or more!

Water is important for our daily activities and to keep us healthy, however, water requirements vary according to individual needs. Your water requirements depend on many factors, including your current health, level of activity, and where you live.

While no particular system will suit every person's needs, learning more about your body's requirements can help you figure out how much water to drink each day. Here I discuss:

  • Calculating Water Need Based on Your Individual Factors
  • Risks and Symptoms of Dehydration
  • How to Know When You're Hydrated
  • Food and Beverages With a High Relative Water Content
Water intake should be determined by age and activity level.

Water intake should be determined by age and activity level.

Water intake by age and gender. Please note that elderly individuals may become dehydrated more rapidly. Water needs also vary by activity. From the Institute of Medicine (2003).

Age/DemographicMinimum Daily Water Intake

Men

3 L

Women

2.2 L

Adolescent Children

2.5 L

Young Children

1.7 L

Infants

0.8 L

Recommended Water Intake by Age, Gender, and Activity Level

Your body loses water through breathing, perspiration, urination, and bowel movements. For the body to work well, you have to replenish the lost fluids by drinking beverages and eating foods containing water.

So how much water does a normal, healthy individual living in a moderate environment require? These are the Institute of Medicine's (2003) guidelines:

  • Men should drink 3 liters (about 14 glasses) of total fluids a day.
  • Women should drink 2.2 liters (about 10 glasses) a day.
  • Babies and infants need 0.7 to 0.8 liters of water daily from breast milk or formula.
  • Small children need 1.3 liters to 1.7 liters every day. Boys and girls age 9 to 13 need 2.5 liters every day.
  • Elderly individuals are at greater risk when dehydrated because of chronic or preexisting conditions.

We all have heard the advice: "Drink eight glasses of water daily." That's about 1.9 L, which isn't that far from the Institute of Medicine guidelines. Try to remember that the rule is actually "drink more than eight glasses of water every day."

This is especially true if you're an active individual. Active individuals need at least twice as much as the daily recommended value—three to four liters—and are recommended to exceed 10 L (Kenney, 2004).

Sources of Water Gains and Losses in Adults. This table is from Porth CM. Essentials of Pathophysiology. 3rd ed. Philadelphia, PA: Wolters Kluwer/Lippincott Williams
& Wilkins; 2011 via Wilson and Morley 2003.

Gains Losses 

Oral intake

 

Urine

1,500 mL

As water

1,000 mL

Insensible losses

 

As food

1,300 mL

Lungs

300 mL

Water of oxidation

200 mL

Skin

500 mL

 

 

Feces

200 mL

Total

2,500 mL

 

2,500 mL

Can You Calculate Target Water Intake Based on Your Weight?

While some websites recommend calculating water intake based on how much you currently weigh, limited studies support this method. Based on the research done in articles cited here, it is best to determine water intake through a holistic assessment of your environment, activity level/type, age, and gender.

Water intake can, however, assist individuals with weight loss. Studies show that drinking water before a meal or instead of a sugary beverage can lower overall calorie intake, as well as assist in burning calories more efficiently (Daniels & Popkin, 2010).

When to Drink More Water

It is recommended that we drink more water under certain conditions, such as when we exercise, are in a hot or dry climate, have health problems, are pregnant, or are breastfeeding.

  • Exercise: After you exercise or take part in any strenuous activity, it is necessary to drink more water to replenish the fluid loss. An added 400 to 600 mL (more than two glasses) of water should be sufficient for short periods of exercise, but intensive exercise that lasts over an hour requires additional fluid intake. How much added fluid is necessary would depend on how much you perspire during your workout and the length or type of training. During long periods of harsh exercise, it's advisable to have a sports drink containing sodium, which will help restore sodium lost in sweat and prevent hyponatremia.
  • Diet: If you consume a lot of caffeine or alcohol then you likely lose more water through urination than the average person. Salt can also dehydrate you, so if you consume a high salt diet, be sure to compensate with more water (Gunnars, 2020).
  • Environment: Hot or humid climates can make you perspire. You'll need to consume extra fluids. Heated interiors can also make your skin lose moisture during the winter season. Additionally, altitudes of more than 8,000 feet (2,300 meters) can induce frequent urination and more accelerated breathing, using up more of your fluid reserves.
  • Sickness or health problems: When you have fever, nausea, or diarrhea, your body loses more fluids. You need to drink plenty of water. In most cases, your doctor may advise oral re-hydration liquids, like Gatorade or Powerade. Other ailments require more fluid intake, such as bladder disorders or kidney stones. Other conditions of the heart, kidney, liver, and adrenal system may upset the excretion of water and require that you control your fluid consumption.
  • While pregnant or breastfeeding: Women who are pregnant or breast-feeding need more water to stay well hydrated. Large amounts of fluid are required to make breastmilk. The Institute of Medicine suggests that expecting mothers drink 2.5 liters (about 10 cups) of fluids every day and women who breastfeed drink 3.2 liters (about 13 cups) of fluids daily.

Risks of Dehydration

Dehydration is defined as "a rapid loss of more than 3% of body weight that’s associated with water and electrolyte disturbance from either water or sodium depletion" (Abdallah et al, 2009 via Collins and Claros, 2011). Studies have shown that even mild dehydration (at least in younger adults) can cause deteriorated mental performance (Wilson and Morley 2003). What many people don't know is that water is lost through the skin and lungs. These quantities of water (aside from sweat) are undetectable by the individual and are thus called insensible water losses. According to Wilson and Morley (2003), a healthy adult loses about 2,500 mL of water a day combined. That's more than a 2 L soda bottle. If, when urinating, you produce less than 30 mL of dark-colored urine, you are most likely dehydrated.

Recognizing Dehydration

The following are some, but not all symptoms of dehydration (Wilson and Morley, 2003).

  • Decreased salivation
  • Dry skin and mucous membranes
  • Urinary tract infection
  • Fever
  • Lethargy
  • Muscle weakness
  • Nausea
  • Decreased urination
  • Sunken eyes

How to Know You Are Hydrated

Drinking enough fluid to help avoid frequent thirst is great, but the real metric is in your urine. Your goal is to produce 1.5 liters (6.4 cups) or more of clear, light-yellow urine every day. Alternatively, 100 mL of light yellow urine an hour indicates that you're likely hydrated. If you're curious about your water intake or have health concerns, consult your doctor or a licensed dietitian. Medical professionals can help you determine the amount of water you need.

To avoid dehydration make sure you drink the right amount of water daily. It's best if you:

  • drink a glass of water or comparable no-calorie or low-calorie drinks with every meal and between each meal;
  • always keep yourself properly hydrated before, during, and after workouts.

Curious to know if you're drinking enough water? Take an online hydration quiz!

Can You Drink Too Much Water?

Over-hydration is an unlikely phenomenon, but it is possible. Over-hydration happens when there is such a high ratio of water to nutrients and salts that an individual begins to feel sick. Symptoms of over-hydration are:

  • Nausea and vomiting
  • Confusion/disorientation
  • Headache

The symptoms overlap with those of dehydration, but don't be fooled! If you're over-consuming your daily recommended amount of water you are most likely over-hydrated (Farrell & Bower, 2003).

One way to lessen this likelihood but continue hydrating? Be sure to drink sports drinks with plenty of electrolytes. Sports drinks can replenish nutrients that may become too dilute in the body when just drinking water.

Foods That Contain Water

Foods That Contain Water

Food and Beverages as Water Sources

Although it's a good idea to drink water to consume at least your daily recommended amount, food can also provide fluids. Typically, food provides about 20% of total water intake. Many fruits and veggies, watermelon and tomatoes, for instance, are 90% water by weight.

Foods with high water to food ratio. List derived from "19 Water-Rich Foods That Help You Stay Hydrated" by Brianna Elliot, RD, 2017.

FoodWater Percent (%)

Lettuce

96%

Cucumber

95%

Celery

95%

Coconut Water

95%

Tomatoes

94%

Zuchini

94%

Cabbage

92%

Cauliflower

92%

Bell Peppers

92%

Watermelon

92%

Broth or Soup

92%

Strawberries

91%

Skim Milk

91%

Cantaloupe

90%

Peaches

89%

Grapefruit

88%

Oranges

88%

Plain Yogurt

88%

Cottage Cheese

80%

Similarly, milk and juice are mostly water. Beer, wine, and caffeinated drinks like coffee, tea, or soft drinks can add more, but these should be consumed in moderation. In excess, caffeine and alcohol are diuretics (in other words, they make you pee more; Palsdottir, 2016).

Plain water is your best choice because it's calorie-free, inexpensive, and easily accessible. Most important, it's what your body needs!

Conclusion

Water is critical to the function of the human body because nearly all bodily processes depend on water. Water flushes out waste, carries essential nutrients around the body, and contributes to cellular function. Dehydration can make you weak, so it's critical to drink enough water for your gender and activity level!

Sources

Collins, M. and Claros, W. (2011) Recognizing the Face of Dehydration. Nursing.

Daniels MC, Popkin BM. (2010) Impact of water intake on energy intake and weight status: a systematic review. Nutr Rev. 68(9):505-21.

Greenfield, Rebecca. (2011) No, Really: You Don't Need to Drink Eight Glasses of Water a Day. The Atlantic.

Farrell DJ, Bower L. 2003. Fatal water intoxication. Journal of Clinical Pathology. 56:803-804.

Institute of Medicine (2003). Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. USDA.gov.

Kenney, Larry. (2004) Dietary Water and Sodium Requirements for Active Adults. Gatorade Sports Science Institute.

Palsdottir, Hrefna. (2016). Drink 8 Glasses of Water a Day: Fact or Fiction? Healthline.

Valtin H. (2002). "Drink at least eight glasses of water a day." Really? Is there scientific evidence for "8 x 8"?. American journal of physiology. Regulatory, integrative and comparative physiology, 283(5), R993–R1004.

Wilson, M. G., & Morley, J. (2003). Impaired cognitive function and mental performance in mild dehydration. European Journal of Clinical Nutrition, 57 (2), S24-S29. Chicago.

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2013 Ferdinand Receno

Comments

some kid on July 01, 2020:

no chart for me...

Benu ray on September 15, 2018:

very nice information receive by me.Thanks.

Pharme961 on June 05, 2014:

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Johne868 on June 02, 2014:

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JP Carlos from Quezon CIty, Phlippines on June 05, 2013:

I grew with this 8 glasses a day. But more often than not, I exceed this quota. True, what we do and the environmental factors as well as my physical health determines how much I need. But i don't consciously count. As long as i feel thirsty, I indulge.

Ferdinand Receno (author) from San Pablo City on June 04, 2013:

RTalloni Thanks so much for the wonderful comment. I'm glad the information has been of use to you.

Will add more informative and useful hubs for people to read.

RTalloni on June 04, 2013:

Thanks for this look at the importance of drinking enough water. I needed the reminder and information is powerful motivation! :)

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