How Much Water Should I Drink?

Q: How much water should I drink each day? I hear all kinds of answers, including 1 ounce of water for every pound of body weight, and six to eight 8-ounce glasses. Which is right?

A: Water is a vital part of any diet and exercise program — not to mention life in general — because it aids every aspect of bodily function. Water is a huge component of muscle and is important for energy production, so if you want to make the most of your workout, make sure you're well hydrated.

There is no real one-size-fits-all approach to water consumption. As a general rule of thumb, men should consume 128 ounces of water daily, and women should consume 88 ounces, but this doesn't mean you need to drink this amount of water every day. Other beverages, as well as the moisture content of foods, also count toward your water intake. The following factors affect how much water you should consume:

Exercise: If you exercise or engage in any activity that makes you sweat, you need to drink extra water to compensate for that fluid loss. Drink 12 ounces of water two hours before a workout, and another 12 ounces 30 minutes before you begin. While you are exercising, you should drink 4 to 8 ounces every 15 minutes. You should consume an additional 12 ounces within 30 minutes of the end of your workout. During intense exercise involving significant sweating — say, during a marathon — you may need a sports drink or coconut water rather than plain water, to replace the sodium lost in sweat.

Environment: In hot or humid weather, you need to drink additional water to help lower your body temperature and to replace what you lose through sweating. You also need additional water in cold weather if you sweat while wearing insulated clothing. Heated indoor air can cause your skin to lose moisture, increasing your daily fluid requirement. Additionally, altitudes higher than 2,500 meters (8,200 feet) can affect how much water your body needs — higher altitudes may trigger increased urination and more rapid breathing, which use up more of your fluid reserves.