The amount of water we need is based upon a number of factors—our size; our activity level, which influences the amount of fluid we lose through sweat; the climate or temperature (higher environmental temperatures increase our fluid losses); and our diet. A diet high in fruits and vegetables provides more total fluids through food than a diet high in fat, meat, and dairy products, for example. Special circumstances in which increased amounts of water may be needed include fever, diarrhea, kidney disease, or any situation where excessive fluid losses occur through normal body elimination processes.

We lose water daily through our skin, urine, bowels, and lungs (as water vapor in the air). About half of our water losses can be replaced with the water content in our food. The remaining half requires specific fluid intake, primarily from drinking good water. Caffeinated beverages, such as coffee, tea, cocoa, or colas, and alcoholic beverages do not count as the same volume of water because they act as diuretics in the body, increasing fluid losses from the kidneys.

The average human requirement is about three quarts of water per day, including food and beverages. An inactive person in a cool climate may need less, while an athlete training in the desert will need much more. People who eat a lot of fruits and vegetables, which are high in water content, will require less drinking water than people who consume proportionally more meats and fats, which are more concentrated and require additional water to help utilize them. In addition to a healthy diet containing fresh fruits and vegetables, I recommend that the average person consume at least one and a half to two quarts of water daily, because I also suggest a physically active lifestyle with daily exercise.

Water is best consumed at several intervals throughout the day—one or two glasses upon awakening and also about an hour before each meal. Water should not be drunk with or just after meals, as it can dilute digestive juices and reduce food digestion and nutrient assimilation. Some people like to drink a glass or two in the evening to help flush out their systems overnight, even though this may result in getting up during the night to urinate. It is important to drink water to avoid problems such as constipation and dry skin. Drinking enough contaminant-free water is likely our most significant nutritional health factor. Water will keep us current, clean, and flowing through life.