Water Nutrition Facts and Health Benefits

Water

Verywell / Alexandra Shytsman

Water is essential for life because it helps regulate body temperature, maintain blood volume, flush toxins from the body (via urine), and transport nutrients inside the body. An adult's body is about 55% to 60% water; in children and babies, the percentage is even higher. A lack of water intake, or increased water loss (such as through sweating), results in dehydration, which can be dangerous and even fatal.

Water Nutrition Facts

The following nutrition information is provided by the USDA for 1 cup (8 fluid ounces or 237g) of tap water.

  • Calories: 0
  • Fat: 0g
  • Sodium: 9.5mg
  • Carbohydrates: 0g
  • Fiber: 0g
  • Sugars: 0g
  • Protein: 0g

Carbs

Drinking water does not contain any carbohydrates, sugar, fiber, or starches unless it has added flavorings such as juice.

Fat

Drinking water is fat-free.

Protein

Drinking water is not a source of protein.

Vitamins and Minerals

Some water contains minerals such as calcium, fluoride, iron, potassium, or sodium, depending on the source and whether or not it's filtered or distilled. Some flavored or enhanced water products contain added vitamins or electrolytes.

Health Benefits

Drinking plenty of water each day will ensure you get enough water for essential body functions. Drinking water helps regulate body temperature and keep you cool when you're in hot temperatures. The Health and Medicine Division of the National Academies of Sciences, Engineering, and Medicine recommends that adult women consume about 91 ounces of water each day and that men get about 125 ounces. That includes all sources of water, including the beverages you drink and the foods you eat. 

Prevents Dehydration

Some research indicates that even mild levels of dehydration can impair physical function, or at least make you feel like it requires more effort on your part to do things. Dehydration can sometimes trigger headaches, too.

Most of the time, and as long as you're healthy, thirst can be your guide, so if you're thirsty, you require more water. It's possible that thirst mechanisms don't work ​as well in some older people or during strenuous exercise.

You'll need more water and should drink before you are thirsty if you're in hot temperatures or if you're physically active, like during hard exercise or a labor-intensive job. Women who are pregnant or nursing need extra water as well.

Regulates Body Temperature

One of water's important functions in the body is to regulate temperature. For example, sweating is an efficient way to cool the body when it's too hot.

Can Improve Mood

Mild levels of dehydration can also affect your cognitive function and mood, so drinking enough water is also good for your brain function. One study showed that being dehydrated by just 2% impaired some cognitive functions.

Removes Waste

The kidneys use water to produce urine, which helps the body rid itself of toxic substances. Staying hydrated helps the kidneys work more efficiently.

Improves Digestion

Water is also important to the functioning of the gastrointestinal tract; the stomach needs water to create digestive secretions. Insufficient hydration can also cause constipation.

Reduces Exercise-Induced Asthma

Strong clinical evidence shows that low fluid intake is associated with exercise-induced asthma, in which physical activity triggers symptoms of asthma, such as wheezing and shortness of breath.

Helps Manage Healthy Weight

Since water is calorie-free, drinking water can help you lose or maintain weight when you drink it in place of high-calorie beverages. It can also help you feel full so that you consume fewer calories.

Allergies

Water allergy is very rare, but it is possible. The condition is called aquagenic urticaria. People with it develop itchy hives when drinking water or coming into contact with it. Since water is obviously essential for life, treatment is required to manage this condition.

Adverse Effects

It is possible to drink too much water, but under normal circumstances, it is unlikely. Drinking way too much water too quickly leads to a condition called hyponatremia or "water intoxication." When that happens, the sodium levels in your blood drop way too fast and make you sick.

Hyponatremia is a medical emergency and can be fatal. The condition can occur in marathon runners and other endurance athletes who drink a lot of water without replacing the salt they are losing through sweat.

Varieties

You can get drinking water from your faucet (tap water), or buy it bottled. Bottled water is regulated by the Food and Drug Administration and must be just as clean and safe as tap water. It may be carbonated ("sparkling"), distilled, purified, or filtered, or may contain minerals from an underground source. Some bottled waters have additives such as oxygen or protein.

Adding a few drops of flavoring or a small packet of crystals doesn't transform your water into something else or add significant calories. In fact, if you don't like the taste of plain water, adding a bit of flavoring is a good way to want to drink more.

Just about everything with fluid counts as water. Even dry foods like toast or crackers have a little bit of water. Some foods, such as soup and watermelon, have more water than others. The National Academies says that about 20% of your water intake comes from the foods you eat (this increases if you typically eat a lot of fruits and vegetables), and about 80% comes directly from fluids including water, milk, soft drinks, juice, and even caffeinated beverages such as coffee and tea. 

Be careful with drinks that are high in sugar and calories, and energy drinks that can also be very high in caffeine.

Storage and Food Safety

In general, tap water in the United States is very safe to drink. It is regulated by the Environmental Protection Agency (EPA) and tested frequently to make sure it is free of bacteria and contaminants.

If you get your drinking water from a private well, it is important that you have it tested to make sure it is safe. The Centers for Disease Control and Prevention (CDC) recommends testing well water at least once a year. Your local health department or county government can help you find a licensed testing laboratory.

Bottled water may come with a sell-by date, but it will generally last a very long time. After about a year, the taste may change slightly, but the water will still be safe to drink. If you bottle your own tap water, use a clean glass or plastic container, and rotate it out every 6 months.

How to Prepare

It's perfectly OK to enhance the flavor of water so it's more palatable to you. Aside from commercial sugar-free flavorings, DIY by adding a slice or two of lemon or lime to a tall cold glass of water. Or add sliced strawberries, cucumber, or fresh herbs. When the weather is cold and you want something warm, make herbal tea or hot water with lemon. If it's the fizz you crave, try sparkling water.

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