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Myths and Facts About Hydration

Published on Jun 15, 2017
Authored by Pfizer Medical Team

Are you one of the many people who think being well hydrated means drinking eight 8-ounce glasses of water every day? Or that only the water we drink hydrates us? Or that there’s no such thing as drinking too much water?

The fact is, hydration is essential for life, but there are a number of myths about it. Read on to learn more.

Myth: Only the water we drink hydrates us.
Fact: In addition to the water we drink, we also get some of our water from the foods we eat and the beverages we drink. According to the Institute of Medicine, about 80 percent of people's total water comes from drinking water and beverages—including caffeinated beverages—and the other 20 percent is derived from food. These include fruits and vegetables that have a high percentage of water such as tomatoes, celery, and melons. They also include soups, milk, and juices. Water from all of these sources adds up to give us our daily fluid intake, or total water.

Does drinking more water really…

Help us lose weight by making us feel full?
Help improve our skin tone?
Help rid us of toxins?

The same answer applies to each of these claims: There is no clear scientific evidence that increasing the amount of water we take in does any of those things. On the other hand, there is no clear scientific evidence that it doesn’t. The bottom line is, researchers have more work to do before anyone can reach any firm conclusions about the benefits of increasing our water intake.

Myth: We need 8 glasses of water a day.
Fact: Not only is this simply not the case, no one really knows where the recommendation came from! The fact is, different people need different amounts of water to stay hydrated. It all depends on how much we perspire, which is affected by the climate we live in, the kinds of clothing we wear, and our activity levels. Other factors that impact how much water we need include certain medical conditions we may have such as diabetes or heart disease.

While there is no single recommendation for how much water each of us needs, a good rule of thumb is to drink fluids when you are thirsty and have beverages with your meals. For most of us, that’s enough to stay hydrated. But try to stay away from sweetened beverages as they can have too many calories.

Another way you can estimate if you are well hydrated is by the color of your urine. If it’s pale or straw-colored, you are likely well hydrated. Dark urine can indicate that you’re not.

Do sports drinks help with hydration?

Sports drinks that have electrolytes can be beneficial for those who do intense, vigorous exercise in hot weather. The downside is that they can contain added sugars and lots of calories. Experts recommend drinking water while we exercise and then having a healthy snack such as a banana or some orange slices afterwards.

Myth: There’s no such thing as too much water.
Fact: Though it’s rare, there actually is such a thing and it is called overhydration. For most people, the kidneys get rid of excess water. But for those whose kidneys don’t work as well as they should, or who have certain liver or heart problems, overhydration can happen. It can lead to having too little sodium in the body, which can be dangerous. Signs of overhydration are usually mild and include being easily distracted and having little energy. But if overhydration happens quickly, it can cause confusion, seizures, or a coma.

Why hydration is so important

One thing about hydration that is absolutely a fact is that we need water to survive. Here are some of the many things water does for us:

  • Helps our heart pump blood more easily through the blood vessels to the muscles.
  • Helps our muscles work efficiently.
  • Keeps our body at a normal temperature.
  • Lubricates and cushions our joints.
  • Protects our spinal cord and other tissues.
  • Helps us get rid of waste through urination, perspiration, and bowel movements.

The bottom line is, if we don’t get enough water, our body becomes dehydrated. And dehydration can lead to everything from minor problems such as swollen feet or headache to potentially deadly conditions such as heat stroke.

[1] [2] [3] [4] [5] [6] [7]


  • 1. Negoianu D, Goldfarb S. Just add water. J Am Soc Nephrol. 2008;19:1041-1048.
  • 2. American Heart Association: Staying Hydrated — Staying Healthy. Accessed April 17, 2017.
  • 3. Centers for Disease Control and Prevention: Water & Nutrition. Accessed May 4, 2017.
  • 4. Centers for Disease Control and Prevention: Get the facts: drinking water and intake. Accessed May 4, 2017.
  • 5. MedlinePlus: Water in diet. Accessed April 17, 2017.
  • 6. The National Academies of Sciences, Engineering, and Medicine. Report Sets Dietary Intake Levels for Water, Salt, and Potassium to Maintain Health and Reduce Chronic Disease Risk. Accessed May 31, 2017.
  • 7. Merck Manual. Overhydration. Accessed April 17, 2017.
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