Hyponatremia sometimes makes headlines when someone drinks too much water. Excessive water consumption causes low salt levels in the body and may lead to death. For this reason, athletes often fear drinking too much water, although the opposite is usually the case. Even if you are not an athlete, you probably need to drink more water, especially during the hot, summer months.

How Much Water to Drink for Hydration during Exercise

In the Wilderness Medicine Institute’s article, “Hydration: The WIWU Principle,” Buck Tilton explains that a person can lose up to two liters of water per hour in sweat during vigorous exercise. Add to that the amount of water lost from urination and breathing.

Post-exercise headaches are a sign that one has not gotten enough water during a workout. Inadequate water consumption also leads to fatigue and reduced endurance. How much water should one drink? It varies.


Tilton reported the International Sports Medicine Institute’s recommendation of “one-half to two-thirds ounce of water per pound of body weight per day.” For a 150-pound person, that would be 75 to 100 ounces per day, or nine to 12.5 cups spread out through the day.

According to Tilton, “Recent research indicated,” that people can absorb “as much as one-quarter liter every 10 to 15 minutes during periods of intense exercise.” That is equivalent to a little less than one cup of water. An athlete that exercises at a high-intensity for three hours should drink a minimum of 12 cups of water, and may consume more than one gallon, or 16 cups.

Hydration Prior to Exercise

The Iowa State University Extension recommends drinking seven to 10 fluid ounces of water every 10 to 15 minutes during exercise, but hydration prior to exercise is equally important. They recommend hydrating with 17 to 20 ounces of water two to three hours prior to exercise.

Thirst is a poor indicator of when to drink. In fact, thirst is a sign that one is already experiencing dehydration. The goal is to prevent this during exercise. According to “Eat to Compete: Fluids,” published by Iowa State University, “It takes 24 to 36 hours after dehydration to fully recover the muscular strength and endurance lost due to dehydration.”

Proper hydration can be a difficult balance for endurance athletes who exercise several hours at a time. Hyponatremia becomes more of an issue as salt is lost through sweat, and water is taken in to maintain hydration. Supplements are often used to help maintain electrolyte balance. For most athletes, the sodium in their pre-exercise meals is enough to get them through their workouts.

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