Why is Drinking Water Important and How Much Water Should You Drink

Why is Drinking Water Important and How Much Water Should You Drink

Why is Drinking Water Important and How Much Water Should You Drink

By: Julie Mancuso, founder of JM Nutrition, team of registered dietitians and nutritionists at JM Nutrition, Ahsan Zaman, Public Health Consultant. Learn about our team


In this post:

  • Why is drinking water important?

  • Benefits of drinking water

  • Dehydration symptoms

  • How much water should you drink?

  • Factors that affect water consumption


Why is Drinking Water Important?

Water and the Connection to the Body

What comes to mind when you think of the word nutrient?

Is it carbohydrates? Fats? Protein?

The most important nutrient, however, and the one that may not immediately come to mind, is water.

What is a nutrient?

According to Merriam-Webster, a nutrient is a substance or ingredient that promotes growth, provides energy and maintains life.

Since a nutrient is a compound that is essential to life (1), water is no doubt fits this description. 

Water and the body

Water makes up approximately 60-70% of our body weight. Due to the average difference between the body compositions, males have a higher water content than females.

Additionally, babies have the highest composition of water (in terms of the percentage).(2)

Unlike other nutrients such as fat and protein, water is not stored. As a result, the body is in constant need of its replenishment. Whether through drinking fluids or eating foods that contain water, it’s important to be aware of the amount of water you ingest in order for the body to function optimally.


Benefits of drinking water

Undoubtedly, the benefits of drinking water are many and varied. They are also critically important.

Let’s assess the importance of drinking water by looking at some of these benefits.


1. Water helps to maintain the health of cells in the body

Drinking water is important because of its impact on cells.

Cells are composed of nearly 70% water. As a result, water replenishment is crucial for cell health and function. Water also assists in carrying nutrients to cells. (2, 3)


2. Water helps to regulate body temperature

It is a well-known fact that water keeps the body temperature balanced through sweating.

When the body becomes too warm, due to hot weather or a fever, sweating helps to cool the body temperature.(2)

As such, the importance of water cannot be understated as thermoregulation is vital to our survival.

Related: Summer Nutrition Tips


3. Drinking water aids digestion

An important benefit of drinking water is that it helps the digestive system break down foods. (2) This effectively facilitates the absorption of nutrients needed by the body.


4. Water carries nutrients through the body

Water is essential for another reason: it transports nutrients in the body.

More specifically, carbohydrates, fats and proteins are carried in the bloodstream after the digestive system absorbs the essential nutrients for energy. (2) As a result, water is indispensable. 


5. Drinking water prevents constipation

Another benefit of drinking water is that it helps to reduce constipation. In fact, dehydration is the leading cause of constipation, which can bring considerable digestive distress

Water is crucial as the large intestine absorbs it and changes the digestive waste from liquid into stool. (5) In other words, water is needed to move waste through. This, in turn, helps you stay regular.

Related: Gastrointestinal dietitians


6. Water helps to keep blood pressure steady

This is an important, and often neglected, benefit of drinking water.

According to Medicinenet.com, not drinking enough water has the following effects on blood pressure:

  • Results in thicker blood due to the reduced water content in the blood.
  • Causes the kidneys to release renin, resulting in sodium and water retention in the body to correct the low fluid volume and leading to high blood pressure.
  • Leads to the release of vasopressin hormone in the brain, causing the blood vessels to narrow and resulting in sodium retention in the body.

Related: Dietitian for high blood pressure


7. Water stabilizes the heart rate

When dehydrated, blood volume (the amount of blood in your system) is lowered. (6)

To compensate, the heart beats faster in order to get as much blood as it can moving around the body.

When you are hydrated, however, your heart rate is steady (excluding other factors such as exercise and stress).

Additionally, according to the Heart Foundation, “when you are dehydrated, your blood retains more sodium, thickening your blood and making it harder for your blood to circulate through your body. Keeping your body hydrated helps your heart pump blood more easily and allows oxygen to reach your muscles, which helps the muscles work efficiently.”

This is no doubt one of the more important benefits of drinking water, as noted by our team of heart health dietitians.


8. Water lubricates and cushions joints

Another benefit of water that is worthy of note is it helps to lubricate and cushion joints.

How does water help in this process?

Joints are surrounded by liquid called synovial fluid, of which water is a component. This fluid keeps the joints (e.g., wrists, knees, ankles, shoulders and hips) smooth and reduces friction between them, much like lubricant for a car engine. (2,7)

Related: Arthritis dietitian


9. Water helps to eliminate waste

As alluded to in a previous point, drinking water is important because it helps to eliminate metabolic by-products or waste products, excess electrolytes (sodium and potassium) and urea through urination.

Increased water intake results in greater filtration of the blood in the kidneys, as kidneys act like a blood cleaner. This in turn produces more urine, which removes any waste in the bloodstream. (2,8)


10. Water reduces the likelihood of stone formation

In our nutritional counselling practice, our dietitians who counsel clients with kidney health concerns, frequently underscore the importance of water in kidney health.

Two of the problems that may arise as a result of chronic lack of water intake  are kidney stone and gallstone formations.

Related: Dietitian for gallbladder health

There is strong evidence in support of the fact that water intake may reduce the chances of kidney stones. There is also a possibility of water intake preventing gallstones as well. (2,8)


11. Water may help reduce the risk and recurrence of urinary tract infections (UTIs) in females

Other than taking antibiotics, healthy water intake may play a role in preventing UTIs, such as cystitis, by clearing the bladder of bacteria.

This is a low-risk and low-cost intervention method. (2,8)

As always, we recommend visiting your family physician if you are having concerns or encountering symptoms.


12. Water keeps the skin moisturized

Drinking water is also important because it may play a part in skin health, according to some studies on the connection between water and skin. Although the correlation is far from being conclusive, it is worth mentioning. 

Related: Skin health nutritionist

Acne nutritionist



13. Water moistens the mucous membranes

Furthermore, water is beneficial because it moistens the mucous membranes, such as the lungs, mouth and nose.

The mucous membrane is a layer that secretes mucous in order to create a thick protective fluid around the area–in this case, for breathing and keeping dirt and pathogens from entering into the body. (2) Water aids this process.

In addition, dry mucous membranes can contribute a whole host of health problems. For example, dry mucous membranes in the lining of the nose may lead to frequent nose bleeds.


14. Water keeps amniotic fluid volume levels up during pregnancy

According to our pre-natal and post-natal nutrition dietitians, drinking enough water is instrumental in upping the levels of amniotic fluid.

Too little amniotic fluid, which thins the amniotic sac, can create complications during pregnancy.

For example, it can have a negative impact on the baby’s development.

It can also lead to a compressed umbilical cord.

Similarly, it can create complications during birth. (10)

For this reason, expectant mothers should ensure proper hydration levels. Related: Pregnancy Nutrition Tips


15. Water helps repair tissue

Another noteworthy benefit of drinking water is its integral role in tissue repair.

According to Franklin Rehabilitation, “there are three stages of tissue repair following injury. In each stage, water is a primary catalyst to help move from one stage to the other.” 


Dehydration Symptoms

It is common knowledge that dehydration is the condition that occurs when the body loses too much water and fluid.

This loss may be caused by a range of factors:

  • lack of fluid intake,
  • illness causing diarrhea,
  • vomiting,
  • prolonged and/or excessive sweating,
  • excessive urination,
  • or medication that causes a person to urinate or sweat. (11)

When experiencing any of the above symptoms, it is especially vital to stay hydrated.

System dehydration may be problematic, resulting in the impairment of mental and physical performance, as well as physiological function.

There are a number of symptoms that you can experience when you are mildly dehydrated. As such, it is important to pay heed to these signs. Otherwise, you risk other consequences, some severe and potentially life-threatening. (11).

Dehydration symptoms include:

  • Feeling very thirsty.
  • Dry mouth.
  • Urinating and sweating less than usual.
  • Dark-coloured urine.
  • Dry skin.
  • Excessive tiredness.
  • Dizziness.
  • Confusion.
  • Fainting.*
  • Rapid heartbeat.*
  • Rapid breathing.*

*The latter three symptoms are more dangerous and medical help should be sought as soon as possible. (11)

It is also important to understand the physiological effects of dehydration within the body in a more comprehensive manner.


Physiological signs and symptoms of dehydration

1. Reduction in Physical Performance

It is common knowledge that after physical exertion, you lose water and can become dehydrated. This is the reason why drinking water is important after physical exercise.

Over the years countless athletes have been studied to understand the effects of dehydration on performance. Decrements in physical performance were observed when these athletes were dehydrated by as little as 2%. (8) For those engaging in physical activity, mild dehydration can reduce endurance, increase fatigue, reduce motivation and increase the perceived effort. (8)

The sports dietitians and nutritionists at JM Nutrition continue to emphasize this fact to many of our fitness and sports nutrition clients who frequently do not hydrate adequately post-exercise. This occurs to those who take part in team and individual sports, such as endurance sports, combat sports and strength training.

Once rehydration takes place, however, these physical/mental performance reducers are reversed. 


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2. Reduced Cognitive Performance and Behaviour Change

As mentioned earlier, brain function can fall victim to dehydration. This is no doubt a common symptom of dehydration.

Certainly, irritability, cognitive decline and confusion can occur from a lack of hydration.

Mild dehydration can also affect different age groups more so than others.

For example, dehydration in children (aged 10-12), young adults (aged 18-25) and older adults (aged 50-82) can cause disruptions in concentration, alertness and short-term memory. (8)

Related: Dietitian and nutritionist for ADHD

Higher levels of dehydration can even affect arithmetic ability and visuomotor tracking. (8)

Related: Brain health nutrition support

Nutrition Tips to Boost Academic Performance


3. Delirium 

According to the Mayo Clinic, delirium is defined as a serious and considerable disturbance in mental ability. (12) This is a major risk factor for older individuals, especially those with dementia. (8)

Related: Dietitian for older adults

Studies of long-term care residents have also shown that dehydration resulted in cognitive confusion in the elderly. In fact, this is a commonly occurring symptom of dehydration.

It is equally important to note that older individuals often claim to feel less thirsty. This is because of a reduced thirst sensation when compared to the younger population. (7) This can lead to lowered water intake, and consequently, dehydration.


3. Impaired Gastrointestinal Function

As mentioned in the benefits of hydration section, an important benefit of drinking water is that it aids digestion. Reason being, water and other gastric juices help to break down food.

When dehydrated, on the other hand, constipation can occur. In addition, passing stool may be difficult. 

When there is insufficient water in the body, the large intestine absorbs more water from the food waste travelling through. This effectively dries out the waste. As a result, stool passing may become painful.

A study which zeroed in on this area indicated that those who were water deficient had reduced constipation after increasing their water intake. (8)

Learn more about the basics of digestive health.


4. Suboptimal Kidney Function

Kidneys are essential in keeping a water balance and regulating blood pressure. This is done by filtering the blood. Anything unwanted is then disposed off in the urine. (7)

When the water content is too low in the blood, less filtration occurs–clearly a significant negative symptom of dehydration.

Furthermore, dehydration may lead to kidney damage, though this may be reversed, if treated correctly. (13)

Related: Dietitian for kidney disease


5. Negative Impact on Heart Function

A reduction in blood volume can occur via blood loss or through the loss of body water from sweating. Blood volume is distributed differently relative to the position of the heart, whether standing or lying down.

As a result, moving from one position to the other may lead to a drop in blood pressure and increased heart rate. At times, this ay even lead to syncope (sudden fainting).

According to our registered dietitians for heart health, this hypotension (low blood pressure) can be managed by drinking 300–500 ml (1-2 glasses) of water. Water intake may reduce the heart rate, while increasing blood pressure in individuals who have normal blood pressure, as well as those who suffer from high blood pressure.


6. Increased Headaches

Another symptom of dehydration is the development of headaches. This includes potential increased intensity and/or frequency of headaches.

Some studies have even observed that water deprivation may not only cause migraines, but prolong them.

Clinical studies have also shown that those who were suffering from dehydration headaches felt relief between 30 minutes and 3 hours, after rehydrating themselves.

The proposed reasoning here is that there is a reduction of plasma volume (portion of the blood) in the head. (8)

Related: Nutritionist for management of headaches


7. Hydration and the Connection to Chronic Diseases

With water being the most important nutrient, much evidence has shown that a lack of it can be a cause of multiple morbidities. (8)

There is strong evidence that links dehydration to being a major cause of urolithiasis (kidney stones), as supported by kidney health dietitians.

Evidence also suggests that hydration is associated with a reduction in the incidence of constipation, hyperglycemia in diabetic ketoacidosis, dehydration in infants and exercise asthma.

In addition, there is a connection of sufficient water intake to a reduction in hypertension (high blood pressure), thromboembolism, urinary tract infections, fatal coronary heart disease and stroke. (8)

Further clinical studies are soon to be conducted to further solidify these associations. Nonetheless, it appears that symptoms of dehydration manifest themselves in many ways in the realm of chronic disease


How Much Water Should You Drink?

So how much water should you drink per day then?

The answer is not so cut and dried, as it is often purported. Reason being, the amount of water you should drink every day depends on numerous factors, both internal and external. As such, the amount varies from person to person, and from situation to situation.


Factors that influence how much water you should drink

Water intake throughout the day should be modified according to a number of factors. These include:

Activity level

Your activity level throughout the day corresponds to the amount of water you should take in. For example, if your line of work requires a great deal of moving around throughout the day, then chances are that you will require more water than a person who is largely sedentary during the working day.

Physical exercise

Undoubtedly, physical exercise plays a considerable role in daily water intake. How much water you drink depends on the frequency, intensity, length of time and type of physical activity that is performed.

For example, a marathon runner will likely require much more water than a golfer, under similar conditions. This is largely as a result of the loss of fluid through sweat that must be replenished to prevent dehydration symptoms.


The environment also influences daily water consumption. There is no doubt about it.

Those who live in hot or humid weather conditions will require additional water intake to make up for the water lost via sweat.

Similarly, you will likely need to drink more water during warmer months than cooler ones due to perspiration.

Likewise, if you spend more time outdoors in the sun or warmer environments, both indoors and out. 

Dehydration can even occur at higher altitudes, requiring more regular top-ups.

Related: How to Create a Healthy Food Environment

Health conditions

How much water you should drink also depends on your existing health condition.

For example, if you have a fever or diarrhea, or are vomiting, you will require more water. 

In similar fashion, conditions such as bladder infections and urinary tract stones will call for increased water intake.

Pregnancy and breast-feeding

According to our prenatal and postnatal dietitians, you may also need additional fluids to avoid dehydration symptoms, if you are pregnant or breast-feeding.

Related: Baby dietitian

A word of warning

It’s also important to note that, according to Harvard Health, “It’s possible to take in too much water if you have certain health conditions, such as thyroid disease or kidney, liver, or heart problems; or if you’re taking medications that make you retain water, such as non-steroidal anti-inflammatory drugs (NSAIDs), opiate pain medications, and some antidepressants.”


General guidelines for how much water you should drink 

That said, however, general guidelines that specify how much water you should drink per day exist.

The U.S. National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is as follows:

  • Men: About 15.5 cups (3.7 litres) of fluids a day.
  • Women: About 11.5 cups (2.7 litres) of fluids a day.

These guidelines include fluids from water, other beverages as well as food. Approximately 20% of daily fluid intake usually comes from food and the rest from drinks.

Related: Hydrating Foods For The Summer



The importance of drinking water and the role water plays in so many of the body’s processes cannot be underestimated. This is precisely the reason why so many health professionals and nutrition coaches continue to harp on the fact that people should ensure adequate daily water intake.

If you feel we missed an important benefit of drinking water, a dehydration symptom or any other pertinent information, please feel free to get in touch with us. As always, we welcome input from our readers.

In addition, if you’re interested in an appointment on-site at one of our locations or would like to work with online dietitians and nutritionists, book a free consultation



1. Ghose, Tia. (2015, September 29). Why Is Water So essential For Life? Live Science. https://www.livescience.com/52332-why-is-water-needed-for-life.html.

2. Better Health Channel. Water – A Vital Nutrient. Retrieved April 5, 2022, from https://www.betterhealth.vic.gov.au/health/healthyliving/water-a-vital-nutrient.

3. NIH: National Library of Medicine. National Center for Biotechnology Information. Retrieved April 5, 2022, from https://www.ncbi.nlm.nih.gov/books/NBK9879/#:~:text=Water%20is%20the%20most%20abundant,central%20importance%20in%20biological%20chemistry.

4. Harvard T.H. Chan School of Public Health. The Nutrition Source: Water. Retrieved April 5, 2022, from https://www.hsph.harvard.edu/nutritionsource/water/#:~:text=Water%20helps%20to%20restore%20fluids,is%20necessary%20for%20proper%20digestion.

5. NIH: National Institute of Diabetes and Digestive and Kidney Diseases. Digestive Diseases: Your Digestive System & How It Works. Retrieved April 5, 2022, from https://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works.

6. Monnard, Cathriona Rosemary & Grasser, Erik Konrad. (2017, August 11). Scientific Reports: Water ingestion decreases cardiac workload time-dependent in healthy adults with no effect on gender. Nature.com. https://www.nature.com/articles/s41598-017-08446-4.

7. Tamer, Mahmoud Tamer. (2013, September 6). Hyaluronan and synovial joint: function distribution and healing. NIH: National Library of Medicine. National Center for Biotechnology Information. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3967437/.

8. Popkin, Barry M., D’Anci, Kristen E. & Rosenberg, Irwin H. (2011, August 1). Water Hydration & Health. NIH: National Library of Medicine. National Center for Biotechnology Information. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908954/.

9. McCollum, Benjamin J., Garigan, Thomas, Earwood, John & Jarrett, Jennie B. (2020, April). Can drinking more water prevent urinary tract infections? PMC PubMed Central. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7271893/.

10. NIH: National Library of Medicine. National Center for Biotechnology Information. (2002, January 21). Maternal hydration for increasing amniotic fluid volume in oligohydramnios and normal amniotic fluid volume. PMC PubMed Central. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7045461/.

11. Medline Plus. Dehydration. Retrieved April 5, 2022, from https://medlineplus.gov/dehydration.html#cat_59.

12. Mayo Clinic. Delirium. Retrieved April 5, 2022, from https://www.mayoclinic.org/diseases-conditions/delirium/symptoms-causes/syc-20371386#:~:text=Delirium%20is%20a%20serious%20disturbance,hours%20or%20a%20few%20days.

13. Roncal-Jimnez, C., Lanaspa, M. A., Jensen, T., Sanchez-Lozada, L. G. & Johnson, R. J.. (2015, June 18). Mechanisms by Which Dehydration May Lead to Chronic Kidney Disease. PubMed.gov. https://pubmed.ncbi.nlm.nih.gov/26088040/.


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JM Nutrition is a nutritional counselling service by registered dietitians and nutritionists in Canada. Main office: nutritionist Toronto.

Author: Julie Mancuso

Julie Mancuso


Julie Mancuso is a graduate of the University of Toronto, founder and owner of JM Nutrition, a nutritional counselling service by registered dietitians and nutritionists. For 15+ years, JM Nutrition has helped thousands reach their health, wellness and nutrition goals. Julie and her team regularly lend their expertise to a variety of health publications such as Reader's Digest, Livestrong, Business Insider, Food Network, Today's Parent, MyFitnessPal, Toronto Star, Elle Magazine, Best Life, Weight Watchers and many more.