How much water should we really drink?

Water is an essential ingredient for the life of every organism. It is part of all the cells of our body. Water makes up about 60% of the body weight of adults and up to 75% of the body weight of infants, so it is a very important component of our body, but because we can not store it, we have to supply it in appropriate quantities every day. From today’s entry you will find out how much water we really need.


The functions of water

Water performs many important functions in the body. It is an excellent solvent. What is more, it is necessary for proper digestion process. It enables the formation and swallowing of food bites, and also determines proper action of digestive enzymes. It also takes part in the regulation of body temperature and has a protective function as it protects our internal organs, the brain, the spinal cord, and the eyeball.


Factors which affect our body’s demand for fluids

Our demand for water depends on many different factors. The ones that are especially crucial for how much fluid we should consume during the day are:

  • age
  • gender
  • physical activity
  • diet ingredients
  • temperature
  • climate

Therefore, the demand for water can be expressed both in terms of the daily amount of calories burnt or body mass. Other standards for daily fluid intake were also developed depending on gender and age.


Demand for water, based on the amount of calories burnt

The US Food and Nutrition Commission recommends that adults consume 1000 ml of water per 1000 kcal of energy spent, which gives an average of 1 ml per 1 kcal. When it comes to infants, it is recommended to supply 1500 ml of liquid for every 1000 kcal. In pregnancy, the recommended amount of water should be higher than before pregnancy by about 300 ml / day, while during the breastfeeding period by about 750 ml / day.


Demand for water based on body weight

Other standards for fluid consumption have been developed by the World Health Organization. According to their recommendations, the amount of water consumed by adults should amount to 30 ml / kg body weight / day. These recommendations also apply to older people who are healthy and active. In the case of disabled persons with limited mobility, it is recommended to drink 100 ml of fluid / kg for the first 10 kg of body weight, 50 ml / kg for the next 10 kg and 15 ml / kg for the remaining kilograms of body weight. It is not recommended to use this method for people with excess body mass, because in their case it does not yield reliable results.


Demand for water depending on age and gender

In the first year of life, it is recommended to drink about 700-1000 ml of liquids. With age, the demand gradually increases up to about 2000 ml for adult women and 2500 ml for men. During pregnancy and lactation, the demand increases to 2,300 ml and 2,700 ml respectively. Remember, however, that the recommendations take into consideration both the water contained in all beverages, as well as that from food products.


Factors which increase the demand for fluids

Demand for water increases when body temperature or air temperature is higher and in lower humidity. Also, being at a low temperature may require increased fluid supply. Staying at high altitudes also increases the need for liquids. Demand for water is also related to our diet. For example, a diet high in proteins results in increased diuresis. The presence of products containing a significant amount of fiber in the diet favors higher losses of water with feces. A higher sodium intake may in turn increase water loss through urine.


Water demand in physically active people

Estimation of the demand for fluids in people with a high level of physical activity is another issue.  It should be remembered that with higher activity, larger amounts of water are excreted with sweat, which requires more fluid intake. More information on how many and what liquids should be consumed by a physically active person can be found here.


The effects of excess water and water deficiency

Both deficiency and excess water can have serious health consequences. Such a condition may contribute to the formation of water and electrolyte disturbances and changes in osmotic pressure. Dehydration, even within 2-3%, lowers physical capacity. Water deficiency of 5-8% increases physical and mental inadequacy, and in the case of a 20% deficiency, death may even occur. The serious health consequences to which dehydration may lead include: headaches and dizziness, speech disorders, cognitive impairment, electrolyte disturbances, arrhythmias, urinary excretion disorders, changes in blood pressure, constipation, weight loss, salivary secretion, dry skin and mucous membranes and others.

Not only a deficiency, but also excess water can be harmful. Excessive intake of liquids with low electrolyte content may cause disturbances in water and electrolyte balance. This in turn leads to the following disorders: weakness, nausea, vomiting, lack of appetite, lowering blood pressure, edema, and even convulsions and coma (in severe cases). However, it should be noted that the adverse effects of excessive fluid intake in healthy people are very rare, because their body can remove excess water and thus maintain the water balance. The risk may occur with a single intake of large amounts of liquids that significantly exceed the maximum amount of water released by the body.

As you can see, water has many important functions in our body. Therefore, it is worth taking care of the proper hydration level of our body every day.



  1. Jarosz M. Normy żywienia dla populacji Polski. Warszawa: IŻŻ, 2017.
  2. Jarosz M. Praktyczny podręcznik dietetyki. Warszawa: IŻŻ, 2010.

Anna Lewandowska

Athlete and nutrition specialist. Multiple medalist of the national in traditional karate in European and World Championships. Author of workout plans and books on healthy lifestyle that have helped her motivate over a million of people to change their lives for the better.

Founder of Healthy Plan by Ann, Diet & Training by Ann. CEO of Foods by Ann. Co-founder of Baby by Ann.

Wife of footballer Robert Lewandowski, the captain of the Poland national football team and Bayern Munich player. Read more »

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