Download PDF (174k) - Page will open in a new window Email to a Friend

The H2O Importance

What's the one thing you can't live without?

Chances are, water isn't the first thing that comes to mind. Because water is all around us - from our morning shower to our nightly teeth-brushing - it's easy to take for granted. You can't smell it or even taste it, yet it's the single most important nutrient you can put in your body. It's so important, in fact, that you literally can't live without it.

Water does far more for your body than just satisfy your thirst. While you could survive for as long as six weeks without food, you wouldn't live much longer than a week without water.

Your body of water

At least half of your body is made up of water; on average, an adult's body is 55 percent to 75 percent water (about 10 to 12 gallons). The specific percentage varies from person to person, depending on factors such as body composition, age, and gender.

Every cell, tissue, and organ in your body needs water to function. Water transports nutrients and oxygen to your body's cells and carries away waste products. It regulates body temperature and moistens body tissues such as those in your mouth, eyes, and nose. Water is the primary part of every fluid in your body - including blood, saliva, and, if you're pregnant, amniotic fluid. It helps prevent constipation. And it helps cushion your joints and protect your body's organs and tissues.

In order to keep your body functioning normally - and to avoid dehydration - you need to provide it with an ongoing supply of water. According to health experts, even mild dehydration can interfere with your physical performance. Increased water loss combined with prolonged exposure to high temperatures can lead to heat exhaustion or heat stroke. In a dehydrated state, the body is unable to cool itself properly.

Signs of dehydration include:

  • Excessive thirst
  • Fatigue
  • Headache
  • Dry mouth
  • Little or no urination
  • Muscle weakness
  • Dizziness
  • Feeling light-headed
  • Other "perks" of water

    In addition to keeping your body's processes working smoothly, water benefits your health in other ways.

    Drinking water may help you lose weight by helping you feel fuller (especially when eating foods with a high water content).

    Drinking water can help you feel better. Some health experts report that drinking plenty of water helps with certain medical conditions, such as chronic fatigue, allergies, headaches, depression, digestive problems, urinary tract problems, and constipation.

    How much water is enough?

    Each day, the average adult loses about 2-1/2 quarts of water through perspiration, urination, bowel movements, and respiration. Strenuous exercise and hot, humid weather can cause you to lose even more fluid. Because your body doesn't store an extra supply of water for those times when you need more, you must replace the fluids you lose.

    The Institute of Medicine's Food and Nutrition Board set general recommendations for women at approximately 11 cups and men at approximately 15 cups of total water each day. (Total water means water from all beverages and foods.)2 However, many factors can influence the amount of water your body requires in a day. Some of those include:


    The greater your body weight, the more water you require.


    If you eat a diet high in fiber, your body needs extra water to keep the contents moving through your gastrointestinal tract.

    Level of physical activity When you work or exercise strenuously, your body loses water either through perspiration or evaporation. To help avoid dehydration during prolonged physical activity or in hot temperatures:

  • consume fluid regularly during the activity.
  • drink several glasses of water or other fluid after the physical activity is completed.

  • Climate

    When you're exposed to extreme temperatures, either very hot or very cold, your body uses more water to maintain its normal temperature. In addition, when you're exposed to heated or recirculated air for an extended period of time - on an airplane, for example - water evaporates from your skin and you're more prone to dehydration.


    Both pregnancy and breast-feeding increase the amount of fluid the female body needs.

    Illness Fever, vomiting, and diarrhea all cause increased water loss. Be sure to drink plenty of extra fluids when you're sick.

    Drink up (and eat up)

    Just because your body needs at least 8 cups of water a day doesn't mean you have to stand at the faucet constantly. Rather, you can get your daily water requirement from drinking and eating.

    Certain foods - such as fruits and vegetables - have high water content. The table below gives you an idea of how some foods and beverages can help your body get the fluid it needs:

    91-100% Water 80-90% Water 70-79% Water
    Water Fruit juice Peas
    Milk Cantaloupe Frozen yogurt
    Sports drinks Oranges Popsicles
    Soup Apples Bananas
    Watermelon Pears Some fish
    Strawberries Grapes Eggs
    Broccoli Peaches Casseroles
    Lettuce Gelatin

    Source: Nutrient Data System 2.93 software program


    Get more H2O
    • Take water breaks instead of coffee breaks during the day.
    • Drink a glass of water with each meal and between meals.
    • Be sure snacks include water, milk, or 100 percent juice.
    • Substitute sparkling water for alcoholic beverages. Alcohol can dehydrate you.
    • Drink plenty of water before, during, and after any physical activity (especially in hot weather). Don’t wait until you feel thirsty.
    • Take bottled water with you on outings and while traveling.
    1. “Water: How Much Should You Drink Every Day?”23 May 2006. Mayo Foundation for Medical Education and Research.
    2. “Dietary Reference Intakes: Water, Potassium, Sodium, Chloride, and Sulfate.” Institute of Medicine of the National Academies. February 11, 2004.