Background information
Why drinking a lot of water isn’t as good for you as you might think
by Siri Schubert
So how does our water balance work, anyway?
22.3.2023
Translation: Jessica Johnson-Ferguson
In the course of our lives, we roughly pee enough to fill a swimming pool. And soak our beds with several thousand litres of sweat. What else is there to know about our water balance? Find out here!
The basics are easily explained. Water enters your body in the form of liquids and food. These go down the oesophagus and head to the stomach. They’re then passed on to the small intestine, where most of the nutrients and water from the food are absorbed. Next, the water penetrates the intestinal wall, is fed into the bloodstream and transported to cells throughout the body. Any excess water is then excreted as urine by the kidneys. You also lose some water through breathing and sweating.
How much water do actually you need?
There’s no blanket answer to how much water an individual needs. Why? Because everybody’s different. The required amount depends on many factors. Gender, weight and age all have an influence. As do physical activity and external conditions such as the climate.
In other words, there’s no general rule about how much water is good for you. Nevertheless, there are recommendations. For example, from the World Health Organisation, which says between two and three litres per day.
A recently published study examined the water turnover of participants of different ages and backgrounds. It concluded that the demand for water can vary greatly. In some cases, peak values of more than ten litres per day were reached under certain conditions. Read more about it here.
By the way, about 20 to 50 per cent of our fluid intake comes from food. This means that what we eat is relevant. Fruits and vegetables, for example, consist largely of water. They also contain important electrolytes such as potassium and magnesium. These help maintain water balance in the body.
Kidneys decide how much we pee
The pillars of our water balance are the kidneys. They’re in charge of regulating the urinary system. The two kidney pairs are located on either side of the spine around the 11th and 12th rib. They filter your blood and excrete any excess water through your urine. At the same time, they regulate the salt content in your body, which, in turn, has an influence on your water balance. Salt levels are regulated by hormones including the antidiuretic hormone (ADH), which promotes water reabsorption in the kidneys. If there’s a lack of water in your body, the ADH tells the kidneys to produce less urine. In this case, water serves as a means of transport for waste products in the body. It generally takes about one to two hours for the water we drink to be excreted through urine.
And here’s a fun fact for you: on average, humans produce around 50,000 litres of urine during their lifetime. That’s roughly the equivalent of a standard swimming pool.
Sweating regulates body temperature
In addition to urine, you also lose water through breathing and especially through sweating. The latter also serves to regulate your body temperature. The body can release tiny drops of water through one of the two to four million sweat glands in your skin. This process helps cool you down. So when temperatures soar, your body needs more water to make up for the fluids lost through sweating. An average person loses at least half a litre of liquids a day as sweat – even when they’re doing nothing at all. On very hot days, or when you’re engaged in a tough workout, it can be as much as six litres.
The brain doesn’t like dryness
Staying hydrated isn’t just important for regulating your body temperature, but also for your mental health. The human body is made up of about 73 per cent water, after all. So if you don’t drink enough, this can also affect your mental performance and lead to headaches and problems concentrating.
Header image: Shutterstock
Science editor and biologist. I love animals and am fascinated by plants, their abilities and everything you can do with them. That's why my favourite place is always outside - somewhere in nature, preferably in my wild garden.
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