Will we run out of water before fuel?

Load of garbage. There are now scientific studies coming out that the earlier estimated amount of water per day is actually DETRIMENTAL to health due to thinning of enzymes and a few other factors. I drink about 2 glasses of liquid per week, why am I alive?

the water you intake doesnt mean you drink it. some water comes from the food you eat, when you drink coffe, when you have a soda or soup that is water, and it is true that some people have a lower need for water than others. the 3 liters of water per day is an aproximation, its an average, reality is every person is different. just because you are not dead doesnt mean you are healthy, dehydration can cause diseases like asthma , hypertension , ulcers , allergies and arthritis .

excuse me for using actual sources in a maple story forum, but since you want to call bull and talk about studies lets have us some fun.

http://hgic.clemson.edu/factsheets/HGIC4151.htm

HOW MUCH IS NEEDED?

On an average day, a healthy adult needs 8 to12 cups of water to replace the amount lost through perspiration, breathing, urination, and bowel movements. These fluids must be replaced to avoid dehydration and to keep the body working normally. When eating a high fiber diet, extra water is needed to process the additional roughage.

In general, one quart of water is needed daily for every 50 pounds of body weight. The exact amount of water needed depends on: age; gender; weight; health; level of physical activity; foods eaten; any medications taken; and the weather.

Thirst is one sign that you need fluids. Your current fluid intake is probably adequate if you drink enough water to quench your thirst, you feel well, and you produce a normal amount of urine that is colorless or slightly yellow. However, do not wait until you feel thirsty before drinking something. Sometimes the brain doesn’t get the thirst signal. Older adults often lose the ability to sense thirst.
WHAT DETERMINES WATER NEEDS?

Exercise: When involved in an active sport that makes you sweat, drink plenty of water throughout the day, not just during the activity. Sweat, or perspiration, is the body’s natural way of cooling down, especially on a hot day or when your body gets a real physical workout. Without fluids, your body overheats. To replace fluid loss, drink plenty of water and juice or milk before, during, and after physical activity. These fluids prevent dehydration and the tiredness that accompanies it.

To avoid cramps and dehydration during activity, drink fluids at regular intervals, and continue to replenish with water after the activity is completed. A good rule of thumb is to drink a cup of fluid every 15 minutes during and immediately after exercise.

Drink the following amounts of fluids when exercising rigorously or in very hot weather:

—2 cups during the two hours before exercising;

—1 to 2 cups within 15 minutes of the activity;

—½ to 1 cup every 15 to 20 minutes during exercise. (One medium mouthful of fluid equals about 1 ounce, and 8 ounces equals 1 cup.)

—3 cups for each pound of body weight lost.

For most physically active people, water is the best fluid choice. Sports drinks are necessary only for endurance athletes and people who have exercised for an hour or more, because they lose sodium and potassium through sweating.