Roughly two-thirds of the average adult's body weight is water. Everyday, up to two-and-a-half quarts are spent through perspiration, urination, and exhalation. Because the body has no reservoir, water must be steadily replaced.
Water is critical to health. Second only to air in its necessity, water carries nutrients to cells; aids digestion by contributing to stomach secretions; flushes bodily wastes and reduces risk of kidney stones by diluting salts in the urine; ensures healthy function of moisture-rich organs such as, the skin, eyes, mouth and nose; lubricates and cushions joints; regulates body temperature; and protects against heat exhaustion through perspiration.
Despite its importance and availability, people still are not consuming enough water. The average American drinks only 4.6 glasses daily-not nearly enough. If you wait until your mouth feels dry before reaching for the water bottle, you're already slightly dehydrated because the sense of thirst lags behind your body's need. Other signs of mild dehydration include a flushed face, restlessness or irritability, dry or warm skin, dark colored urine, dizziness, weakness, and headache.
Under regular conditions, the typical person needs a minimum of eight to 10 cups of water daily, at least half of which should be plain water. A glass or cup is equivalent to eight fluid ounces. But pay attention to these additional factors, which can increase that requirement.
Exercise: Because working out burns water quickly, you should drink eight ounces of water before you start and every 20 minutes during exercise. Also be aware that you might need to replace electrolytes lost through extended strenuous activity.
Hot Weather: Environmental conditions greatly affect your body's water usage, so drink one to two cups more daily if the temperature exceeds 80 degrees.
Pregnant or Lactating: If you're expecting a baby, your body needs an extra cup of water daily; increase by three to four cups if nursing.
Caffeine or Alcohol: Because these act as diuretics, drink a cup of water for every cup of these beverages to compensate.
Illness: Drink twice your recommenced amount if you have diarrhea and an extra cup for every degree of fever over 100 to guard against dehydration and help flush out impurities.
All experts agree that drinking enough water is crucial to health, but the debate continues as to whether plain water is the only way to go. Plain water has no calories, no caffeine, and little or no sodium. But other beverages do help to replenish the body with fluid including juices, broth-based soups, and water-rich foods like lettuce and melons.