Sometimes the water in my house can taste weird, so it makes me wonder if there isn't something else in it that shouldn't be there. —Pittsburgh-area high school student

The need for water in the human body is absolutely critical. The human body is 90 percent water, and the brain alone is 75 percent water. We rely upon water for digestion, cooling the body, elimination, and, of course, the circulation of nutrients to every cell. Failure to replenish the supply will mean death. Your need for water is clear.

The exact amounts of water required daily will vary depending upon the foods you eat, the temperature and humidity of the air, the amount of exercise you do, and your individual rate of metabolism. (Some of us just sweat more than others!) As a general recommendation, drinking six to eight glasses of water a day is a good habit to acquire. We also get water by eating solid foods (some of which, like lettuce, tomatoes, and watermelons, are more than 90 percent water), and some from body cells as a byproduct of metabolism.

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