Water, a vital element of the human body
Water is essential for the proper functioning of your body: from maintaining body heat to eliminating toxins. It accounts for approximately 60% of body weight in adults and up to 75% in infants. It plays a role in digestion, blood circulation, body heat management, and waste elimination. And even a moderate lack of water intake can quickly impair your physical and mental performance.
Body water is distributed in two main compartments:
- intracellular water: contained within cells, it participates in metabolic reactions and maintaining cell volume.
- extracellular water: includes blood plasma (20 to 25%), interstitial fluid (75 to 80%), lymph, and cerebrospinal fluid (present in the tissue surrounding the brain). It is essential for the transport of nutrients, waste, and cellular communication.
The body maintains its fluid balance through fine coordination between the brain (hypothalamus), hormones, and kidneys. Uncompensated fluid loss can lead to fatigue, headaches, or a decrease in concentration.
The major roles of water in our body
Regulation of body temperature (thermoregulation)
Water actively contributes to the adjustment of your body heat. During exercise or in hot weather, the evaporation of sweat helps to release excess heat. Blood, rich in water, transports this heat from the organs to the skin, where it is released. Your blood vessels dilate to facilitate this dissipation, or contract to limit it when it's cold. If water intake is insufficient , these mechanisms become less efficient!
Maintenance of blood volume and blood pressure
Water is essential to maintain stable blood volume and sufficient blood pressure, ensuring optimal activity of the heart and blood vessels. Your blood, largely composed of water, transports nutrients, oxygen, and hormones. When water reserves decrease, it thickens, which slows down circulation. This can cause a drop in blood pressure, dizziness, or faintness.
Kidney function and waste elimination
Your kidneys constantly filter your blood to eliminate metabolic waste, such as urea or excess salts. This process depends on a sufficient water intake daily. Water helps to dilute this waste so that it can be efficiently eliminated through urine. If you don't drink enough, your urine becomes more concentrated, which can disrupt proper kidney function. In the long term, this increases the risk of developing kidney stones.
Saliva production and digestion
Your saliva, composed of 99% water, plays an important role in digestion. It moistens food, facilitates chewing, swallowing, and the breakdown of sugars. Regular water intake is therefore essential from the first stages of the digestive process. In case of dehydration, saliva production decreases, which can disrupt ingestion and lead to a dry mouth.
Skin beauty and elasticity
Water is a key element in the composition of your skin barrier . Its water content varies depending on external aggressions and natural evaporation. Well-hydrated skin is more supple, smooth, and radiant. Water ensures tissue elasticity. Conversely, a lack of water dulls the complexion and accentuates fine lines. Drinking enough is a simple but fundamental act for healthy skin.
Joint lubrication and organ protection
Water is an essential component of synovial fluid, which lubricates your joints by limiting bone friction. It also participates in good shock absorption during daily movements. Optimal water intake is therefore essential to preserve mobility and joint comfort. Water also contributes to the protection of vital structures such as the brain, heart, and liver.
What happens if we don't drink enough water?
If you don't drink enough water, the body can no longer compensate for losses due to urine, perspiration, and respiration. A fluid deficit, even slight, can lead to symptoms such as fatigue , headaches , or a decrease in concentration. Signs may appear, such as dark urine , a dry mouth, and dizziness. In the long term, a lack of water can notably increase the risk of kidney stones or urinary tract infections.
What if we drink too much water?
If you drink too much water, it can lead to hyponatremia, which is a low concentration of sodium in the blood. You may also experience symptoms such as nausea, headaches, or confusion. However, this phenomenon is rare and mainly occurs with a massive and rapid intake of water.
How much water should you drink per day?
The EFSA recommends drinking between 1.5 and 2 liters of water per day for children over 14, adults, and the elderly. Infants and children have specific needs, adapted to their age and weight. These reference values for total water intake include water from drinking water, all kinds of beverages, and the moisture in food.
| Age | Daily quantity |
|---|---|
| 0-6 months | 100-190 ml/kg of child's mass |
| 6-12 months | 800-1000 ml |
| 12-24 months | 1100-1200 ml |
| 2-3 years | 1300 ml |
| 4-8 years | 1600 ml |
| 9-13 years | 2100 ml for boys 1900 ml for girls |
| 14 years and older, adults and elderly | 2500 ml for boys/men 2000 ml for girls/women |
However, it is important to adapt your fluid intake according to physical exertion, ambient temperature, and diet. The color of urine is a good indicator of fluid consumption: clear urine is synonymous with good hydration. Remember to take into account the water contained in food, especially fruits and vegetables.
When and how to drink water?
The right times to hydrate
It is important to drink at regular intervals throughout the day, especially at key moments: upon waking, before meals, and during physical exertion. Don't wait for the sensation of thirst to drink: this sensation appears when the body is already dehydrated. Adopting these simple habits helps maintain your concentration and well-being.
Practical tips
To maintain good water balance, drink small sips throughout the day, rather than large quantities all at once. Always carry a reusable water bottle with you to remember to drink. Consider naturally flavoring water by adding a few slices of lemon, mint leaves, or red berries.
In summary: water, source of life and health
Water is essential for many metabolic functions. It plays a role in thermal regulation, digestion, and waste elimination, among others. Drinking regularly, even without thirst, is a simple but fundamental act for health. By adopting this habit daily, you can support your energy, concentration, and overall well-being.
FAQ
What is the role of water in the body?
Water is essential for ensuring the metabolic functions of the human body: thermoregulation, transport and excretion of waste, digestion, and the protection of joints and organs, among others.
How much water should I drink each day?
Approximately 1.5 to 2 liters per day for adults, to be adjusted according to activity, heat, and diet. Intake should be adjusted for infants and children under 14.
Can you drink too much water?
Yes, it is possible to drink too much water, but it is rare.
What happens if I don't drink enough?
A lack of water, even slight, can cause fatigue, headaches, and a decrease in concentration.
Does water help with beautiful skin?
Yes, water contributes to better hydration of the skin barrier, making it smoother and more radiant.
Should I wait until I'm thirsty to drink?
No, thirst is a late signal: it is better to drink regularly throughout the day.
Is tap water as good as bottled water?
Yes, in France, it is controlled and safe, unless otherwise indicated locally.
Bibliography
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). (2010). Scientific Opinion on Dietary Reference Values for Water. EFSA Journal, 8(3), 1459. https://doi.org/10.2903/j.efsa.2010.1459
Hausswirth, C., & Rousseau, V. (2013). Chapter 7. Hydration. In C. Hausswirth (ed.), Improving recovery in sport. INSEP-Éditions. https://doi.org/10.4000/books.insep.1347
Sawka, MN, Cheuvront, SN, & Kenefick, RW. Hypohydration and human performance: impact of environment and physiological mechanisms. Sports Med 45 (Suppl. 1), 51–60 (2015). https://doi.org/10.1007/s40279-015-0395-7
