There is no life without water. All living beings known to us consist to a large extent of it. Water ensures the exchange of cells with each other and thus ensures all vital processes. The element also plays an important role in the human body. Water is our “main component” – quantitatively the most important inorganic part of our body.
The proportion of water in the human body
We learn from childhood that we humans are largely made up of water. But how high is the percentage actually? The information on this in the literature varies widely. This is because the water content is related to several factors. The higher the body fat percentage, the less water there is in the body. Conversely, muscle mass consists of a lot of water – in competitive athletes the water content is therefore increased by around 5%. This means that the proportion of water in men is higher than in women, since the female body naturally consists of more fatty tissue. Age also plays a role. Over the years we increasingly dry out, leaving a toddler consists of far more water than an old person.
How much water is in the human body can only be roughly said. In the case of small children, the proportion is over 70%. A grown man is about 60% water, a woman about 50%. With increasing age, these values drop to below 50%. If you take a man weighing 80 kilos as an example, this consists of around 50 liters of water. That’s 50 kilograms, after all! In extreme situations, the body shows us how vital this water is. Anyone who loses 15% of their body weight in water dies. Our example man, who weighs 80 kilos, does not survive a loss of 12 liters of water.
What we need the water for
So water is essential for humans. It is a good solvent and means of transport and is therefore responsible for the exchange of substances. Like with blood. Probably the most important body fluid consists of 85 to 95% water. The brain is also similarly “liquid” – it has a water content of between 85 and 90%. About 80% of the kidneys, lungs and liver are built up by water. After all, three quarters of the heart and all muscles are made up of water.
The human body cannot store water. In order to maintain the vital functions, fluids must be consumed constantly. If the fluid balance in the body does not fit, this manifests itself, for example, in reduced ability to concentrate, headache and stomach ache and dizziness. Too little water increases the level of toxins in the body fluids. The body then takes some of the water from the blood. As a result, the blood becomes thicker and it becomes more strenuous for the heart to pump it through the body. The result is circulatory problems or, in the long term, serious illnesses such as kidney stones or thrombosis. Enough water prevents it from drying out.
Drink lots of water – but how much?
A lack of water occurs because the body constantly excretes fluids. For example through sweating or urine. If it is particularly hot in summer, if we do physical activity or if we eat very salty food, the need for fluids increases. Opinions are divided about how much should be drunk every day. A blanket value makes little sense anyway.
The human body needs about two to three liters of fluid during the day. We take in part of it through our food. The body can also supply itself to a small extent with water, namely as a “waste product” in some processes. Most of the water required, however, has to be taken up by drinks. Healthy people should drink at least one and a half to two liters of water daily. Another calculation method stipulates that 0.03 liters should be drunk per kilogram of body weight. For our example adult with 80 kilograms that would be 2.4 liters per day. Exercise, physical exertion and a lot of sweating increase this value.
Tap water is ideal for keeping our body hydrated. In Europe it is usually of the highest drinking water quality. However, many areas have to deal with hard water. Even if this is not harmful to health, many people simply do not taste that good, especially when preparing coffee or tea there are compromises in taste. Treatment of the tap water can help.
What our thirst tells us
Many find it difficult to adhere to “drinking rules”. Two liters a day is especially a lot when you are not thirsty and you have to force yourself to sip on the water glass. One often hears that it is already “too late” when the thirst announces itself. The body is already really drying out. However, the counter-argument to constant drinking also sounds plausible: Thirst is made to tell people when to drink. As is so often the case, the middle ground is the right one. In principle, it is by no means bad to listen to one’s feeling of thirst – what else would we have it for? However, if you only drink when you are really thirsty, you will not provide your body with enough fluids in the long run. However, if you move around a little and it is not particularly warm, the body may need less fluid than the drinking recommendation says.
But some people don’t really feel thirsty. These are mostly the chronically ill, old people and children. Older people often also need less fluid, so this is not necessarily a problem. If you feel concerned, you should clarify the right amount to drink with a doctor.
In some people, water intake through food is also very high. Those who like to nibble several pieces of watermelon as dessert are not particularly thirsty afterwards. If large amounts of fruit and vegetables that contain water are consumed, sometimes just one liter of water per day can be sufficient. It is encouraging for many that coffee that has been drunk can also be included in the frequent drink bill. Coffee does not remove as much water from the body as it has long been assumed.
The other end of the spectrum – too much water
Drinking large amounts of water when you are thirsty can also be harmful. That’s why it is sometimes really difficult. The brain then tries to curb the swallowing reflex. Under normal conditions, a little too much water has no negative consequences. The opposite of a water shortage is water poisoning. There are isolated cases in which marathon runners have died because they strictly adhered to the drinking rules. Too much drinking in such extreme situations can lower sodium levels to threatening levels. However, doctors see no such risks in recreational athletes. If the kidney is healthy and functioning normally, problems from too much water are unlikely.