Why drink water? I'm not thirsty

Unfortunately, thirst isn't always a reliable gauge of the body's need for water, especially in children and older adults. As crude as it sounds, a better barometer is the color of your urine: clear or light-colored urine means you're well hydrated, whereas a dark yellow or amber color usually signals dehydration. If you wait until you are thirsty, chances are you are letting your body slip into a mild state of dehydration.

Mild to moderate dehydration is likely to cause:

• Dry, sticky mouth
• Sleepiness or tiredness - children are likely to be less active than usual
• Thirst
• Decreased urine output - fewer than six wet diapers a day for infants and eight hours or more without urination for older children and teens
• Few or no tears when crying
• Muscle weakness
• Headache
• Dizziness or lightheadedness

Severe dehydration, a medical emergency, can cause:

• Extreme thirst
• Extreme fussiness or sleepiness in infants and children; irritability and confusion in adults
• Very dry mouth, skin and mucous membranes
• Lack of sweating
• Little or no urination - any urine that is produced will be dark yellow or amber
• Sunken eyes
• Shriveled and dry skin that lacks elasticity and doesn't "bounce back" when pinched into a fold
• In infants, sunken fontanels - the soft spots on the top of a baby's head
• Low blood pressure
• Rapid heartbeat
• Fever
• In the most serious cases, delirium or unconsciousness

Water is essential to human life: It forms the basis for all body fluids, including blood and digestive juices; it aids in the transportation and absorption of nutrients; and it helps eliminate waste. If you're an average adult, every day you lose more than 10 cups (close to 2.5 liters) of water simply by sweating, breathing and eliminating waste. You also lose electrolytes - minerals such as sodium, potassium and calcium that maintain the balance of fluids in your body.

Normally, you can replenish what you've lost through the foods and liquids you consume, even when you're active. But when you eliminate more water and salts than you replace, dehydration results - your system literally dries out. Sometimes dehydration occurs for simple reasons: You don't drink enough because you're sick or busy, or because you lack access to potable water when you're traveling, hiking or camping.

Other dehydration causes include: Diarrhea, vomiting. Severe, acute diarrhea - that is, diarrhea that comes on suddenly and violently - can cause a tremendous loss of water and electrolytes in a short amount of time. If you have vomiting along with diarrhea, you lose even more fluids and minerals. Children and infants are especially at risk.

Worldwide, more than 1.5 million infants and children die of dehydration resulting from diarrhea every year - 300 to 500 of them in the United States. Most of these deaths occur in the first year of life. Preteens and teens who participate in sports may be especially susceptible, both because of their body weight, which is generally lower than that of adults, and because they may not be experienced enough to know the warning signs of dehydration. Certain medications - diuretics, antihistamines, blood pressure medications and some psychiatric drugs - as well as alcohol also can lead to dehydration, generally because they cause you to urinate or perspire more than normal. The following groups of people must pay extra attention to the warning signs of dehydration:

• Burns. Doctors classify burns according to the depth of the injury and the extent of tissue damage. Third-degree burns are the most severe, penetrating all three layers of skin, and often destroying sweat glands, hair follicles and nerve endings. People with third-degree burns or extensive first- or second-degree burns experience profound fluid loss, and the resulting dehydration can be life-threatening. Anyone can become dehydrated if the loss of fluids outweighs fluid intake. But certain people are at greater risk, including:
  
  
  • Infants and children. Worldwide, dehydration caused by diarrhea is the leading cause of death in children. Infants and children are especially vulnerable because of their relatively small body weights and high turnover of water and electrolytes. They're also the group most likely to experience diarrhea. In the United States, diarrhea remains one of the most common childhood illnesses.
  
  
  • Older adults. As you age, you become more susceptible to dehydration for several reasons: Your body's ability to conserve water is reduced, your thirst sense becomes less acute and you're less able to respond to changes in temperature. What's more, older adults, especially people in nursing homes or living alone, tend to eat less than younger people do and sometimes may forget to eat or drink altogether. Disability or neglect also may prevent them from being well nourished. These problems are compounded by chronic illnesses such as diabetes, by hormonal changes associated with menopause and by the use of certain medications.
  
  
  • People with chronic illnesses. Having uncontrolled or untreated diabetes puts you at high risk of dehydration. But other chronic illnesses also make you more likely to become dehydrated. These include kidney disease, cystic fibrosis, alcoholism and adrenal gland disorders. Even having a cold or sore throat makes you more susceptible to dehydration because you're less likely to feel like eating or drinking when you're sick. A fever increases dehydration even more.