Question

Water

# How much water should I drink daily?

• AMichael Roizen, MD, Internal Medicine, answered
You've heard the advice about drinking eight 8-ounce glasses of water daily about a billion times in your life, right? There's actually no magic (or science) to this number. The right amount of water consumption varies according to your activity level and size. If you want, just drink enough water so that your urine is clear.
• AMarjorie Nolan Cohn, Nutrition & Dietetics, answered on behalf of Academy of Nutrition and Dietetics

The general rule of thumb is to drink (in ounces) half your body weight (in pounds). If you are active, or exercise an additional 8 ounces of fluid for every hour of exercise is recommended for ideal hydration.

• The average adult needs 25-30 ml of fluid per kg (2.2 lb) of body weight to maintain hydration. For the average person this equals about 2 liters, or the recommended "eight glasses a day." However, some factors can increase the amount of fluid you need. People who weigh more need more water; for instance, a 200-pound person needs a little over nine glasses per day to stay hydrated. Altitude also increases fluid needs, and experts recommend people at higher altitudes drink 3-4 liters of water per day.

Calculate your daily needs by dividing your weight in pounds by 2.2 (to get your weight in kg), and multiplying by 25-30 (closer to 25 if you are less active and closer to 30 if you are more active or in hotter, drier climates). Divide this number by 240 (240 ml = 8 oz) to get the number of glasses of water you need daily.
• AMargaret Floyd, Nutrition & Dietetics, answered
Most of us don't drink enough water. But how much is enough? Well, that depends. The "eight glasses a day" standard advice is a little inaccurate because it doesn't account for our different sizes, different activity levels, and what else we're drinking. In his book Your Body’s Many Cries for Water, Dr. F. Batmanghelidj has created a simple formula to determine just how much water you should be drinking given certain factors. Take your body weight in pounds and divide that number in half. That's the total number of ounces of water you need to drink on a daily basis before any diuretic beverages or strenuous exercise.

For example, if you weigh 120 pounds, you need to drink 60 ounces of water a day. If you drink a diuretic beverage (coffee, tea, pop, juice, a sugary drink, or alcohol), you need to drink the equivalent of one and a half to two times the volume of the diuretic beverage just to offset its effects. So, if you drink an 8-ounce cup of coffee, you'll need to drink at least 12 to 16 ounces of water to make up for it -- and that's on top of the 60 ounces (or whatever your specific amount is) of water you're drinking as a daily minimum. The maximum water you should drink in a day is a gallon (128 ounces), so if you're quite heavyset and drink a lot of diuretic beverages, you might have to tweak this formula a little.
• As most of know drinking water is very important to our body but how much water always seems to be a concern for people. The bare mininum intake of water should be at least 64 oz. Now if you live in hotter states like me who live in AZ in the summer months you will want to increase that intake to about 96-128 oz per day. Of course your activity level and how much you spend outside will be a factor as well. A safe bet is drink 8 oz of water everytime you eat.
• Experts are recommending up to 12 cups (96 ounces) of water a day, but for most people, 8 (64 ounces) cups is more realistic. Take it one step at a time by drinking just a cup of water more per day than what you’re used to. Then for every 3 weeks, increase your intake of water by one cup until you reach all 8 cups a day.

• AManuel Torres, MD, Family Medicine, answered on behalf of Baptist Health South Florida

We should drink eight glasses a day, more than a liter typically. You should keep in mind the calories that you are consuming with water substitutes. Other fluids may have calories, but still count. So, for example, if you eat an orange, which has liquid, it should be included when calculating how much fluid you’re consuming. With certain medical conditions, you may need to be careful about what type of fluids you’re ingesting. But generally, if you are drinking water, you're fine.

• Every day you lose water through your breath, sweat, urine and bowel movements. The adequate intake for men is roughly 3 liters (about 13 cups) of total beverages a day. The AI for women is 2.2 liters (about 9 cups) of total beverages a day. At a minimum, drink at least eight 8-ounce glasses of fluid a day.
• The Dietary Reference Intakes from the Institute of Medicine recommend a total daily beverage intake of 13 cups for men and 9 cups for women. This amount is for generally healthy people living in temperate climates. Individual needs vary, so some people can be properly hydrated at somewhat higher or lower levels of water intake. Also, keep in mind that this recommended amount may come from a variety of sources. It includes other beverages -- even those containing caffeine -- in addition to the water that you drink.

When you're exposed to extreme temperatures -- very hot or very cold -- your body uses more water to maintain its normal temperature. Under these conditions, you may need to increase your fluid intake.
• AGrant Cooper, MD, Physical Medicine & Rehabilitation, answered
The American Heart Association (AHA) recommends drinking 6 to 8 glasses of water per day to maintain the fluid balance of someone who is healthy and relatively inactive. Pure water is best, but sports drinks are also a reasonable choice provided they are the type that replenishes electrolytes, not sugary substitutes. Juices are good sources of water and vitamins, but they have more calories. Sodas, coffee, and other drinks that contain caffeine should be reduced or avoided, because caffeine is a diuretic that can cause you to lose much of the fluid you take in.
You need about ten 8-ounce glasses of water daily during sedentary days and at least fifteen on days with 20 minutes of moderate exercise. That means you need to drink about one cup of water every hour and a half throughout the day. Mild dehydration has been linked to the development of kidney stones, constipation, and exercise-induced asthma. Under-hydration also impairs our concentration, alertness, and memory skills.
• AAndrea Pennington, MD, Integrative Medicine, answered
The general rule of thumb is to drink eight 8-ounce glasses of water per day, or enough to make your urine clear. Another way to estimate your daily need is to divide your body weight in half, that's how many ounces of water you should drink each day. For example, if you weigh 200 pounds, you should drink 100 ounces of water! If you've been exercising vigorously, live in a hot climate or have been ill, you may need to increase your intake. Let the color of your urine be your ultimate guide.
• The normal recommendation is 64-96 ounces of water a day depending on your size and weight. If you eat the balanced diet and have a glass of water with every meal, you should stay hydrated. The best way to be sure you have consumed the correct amount of water is to drink water throughout the day until your urine turns clear.

• I recommend to my clients to get a 32 ounce nalgene bottle, fill that up and start with drinking at least one full bottle a day. If you are active, the goal is two full bottles per day. Its helpful to have the same bottle with you all day so you can track how much you are drinking and the best part is that it will keep you from drinking sugar filled drinks, like soda.

If you are active and experiencing muscle cramps, dizziness, or headaches first try drinking more water. Dehydration is the usual culprit but if it continues, definitely visit a doctor.
• AMehmet Oz, MD, Cardiology (Cardiovascular Disease), answered
Much of the food we eat is already 50% water, so we do not need to drink extra water as long as we eat a balanced diet. Learn more on this topic in this video of Dr. Oz.

• Any easy way to figure this out is to divide your body weight (in pounds) in half. Drink that amount in ounces. For example, if you weigh 150 lbs then drink 75 ounces of water.

Dehydration looks and feels lousy: It saps skin and triggers fatigue. Fill your glass regularly and add a squeeze of lemon or orange if you like. Listen to your thirst signals; you don’t have to check off eight full glasses of pure water a day. This old recommendation was busted earlier this year when two kidney experts had a scientific review published in the Journal of the American Society of Nephrology. In it, they show there’s no clear-cut scientific rationale for the average healthy individual to drink eight glasses of water or more a day. Remember, too, that you get water through a variety of sources like fruits and teas.

From The Mind-Beauty Connection: 9 Days to Less Stress, Gorgeous Skin, and a Whole New You by Amy Wechsler.

• Unless the doctor says not to, drink about 8 cups of water a day. Water helps your body work better, especially in hot, dry climates. It also may keep you from drinking unhealthy drinks like soda pop.
• To stay well hydrated, drink water throughout the day. You can take your weight in pounds, divide by 2, and that will show the number of ounces you need to drink daily. If you are working out for an hour you can add another 10 ounces. Drink 1-2 extra glasses of water for every caffeine or alcoholic drink you consume.

• AEva Cwynar, MD, Internal Medicine, answered
The basic rule of drinking six to eight 8-ounce glasses a day still applies. If you want to get more specific, multiply your weight by 0.6 and that will give the amount of ounces you need in a day (if you're an athlete, multiply your weight by 0.75). Don’t drink all your water at once—sip it throughout the day. Many ear, nose, and throat doctors say that drinking too much water at one time can produce postnasal drip and pharyngitis (inflammation of the part of the throat between the tonsils and the larynx). Plus studies have shown that if you drink all those ounces of water all at once, you don't get the same benefit. It just goes right through you.
• AStaness Jonekos, Health Education, answered
There is no one water consumption formula that works for everyone. The Institute of Medicine advises that women consume 9 cups (2.2 liters) of total beverages per day. Your personal water needs depend on many factors:
• For every 20 minutes of exercise you do each day, drink 8 ounces of water.
• Hot or humid weather can increase sweating, increasing your fluid retention.
• If you are ill, suffering from a fever, vomiting or diarrhea causing a loss of fluids, drink more water.
• If you drink alcohol, add an equal amount of water. For example, 6 ounces of wine should be matched with 6 ounces of water consumption.
• Bottom line: hydrate based on your needs.
• ABob Greene, Physiology, answered on behalf of The Best Life

I recommend a minimum of six 8-ounce glasses a day for most people, but if you're active or live in warm climates, you may need a little more. And don't go overboard: There's no need to gulp down 12 glasses unless, of course, you’re training for a race or hiking the Grand Canyon.

Having trouble hitting the daily six-glasses goal? Make it easier by getting into the habit of drinking a glass with each meal. And you should try to stick with plain old water instead of drinks like iced tea or lemonade. If you’d like to add some flavor, try a squirt of lemon, lime, grapefruit or even tangerine. Other zero-calorie alternatives that can help you reach this goal include herbal iced tea, carbonated water or flavor infused waters.