How much water does the human body need? 

For water to optimally perform its important functions in our body, the quality of the water is crucial.
The human body is made up of about 60 to 70 percent water. The human brain, with its enormous performance capacity and complex structure, as well as the blood flowing through our veins, consists of up to 90 percent water, and our saliva is 98 percent water. Water thus flows through every single cell of our body. 

Most people simply underestimate the enormous effectiveness and necessity of water for our body. Without realizing it, a person typically drinks about 20 percent too little of this precious liquid each day. 

Under normal circumstances – that is, while sitting or reading a book – you need 35 milliliters of pure water for every kilogram of body weight per day. For a 70-kilogram adult, this amounts to about 2,500 milliliters or approximately 10 glasses of liquid (at 250 milliliters) per day. This requirement is subject to fluctuations: just being in cold or hot conditions increases our water needs.

Factors such as stress and physical activities also increase consumption (e.g., through perspiration or faster breathing). When there is a lack of water, the body signals its short-term need through thirst. 

Water primarily enters the body through food: on average, an adult consumes 1.5 to 2.5 liters of water per day. However, even higher amounts are well tolerated by healthy individuals, as the kidneys can excrete nearly 1 liter per hour. The maximum amount of fluid intake that can be tolerated even in the long term is about 10 liters per day. Up to 65 percent of the water consumed is absorbed in the small intestine, and 35 percent in the large intestine. The salt content in the liquid plays a crucial role in water excretion.

A look inside the body 

When you eat a cookie, it is broken down in the long muscular tube that starts at the mouth, runs through the stomach and intestines, and ends at the anus, so that the nutrients can eventually be absorbed into the bloodstream and distributed to the body cells.

Water filters in our household 

A water filter is not just a water filter. The drinking water from the tap is, as authorities, representatives, and experts repeatedly emphasize, the most controlled food in Germany. Water companies continuously monitor about 49 chemical and organic parameters of the drinking water regulation and their legally prescribed limits. 

The increasing contamination of surface waters and groundwater reservoirs makes it increasingly difficult for water companies to treat drinking water. This is caused by agriculture, industry, and population growth with pharmaceuticals, fertilizers, pesticides, chemicals, microplastics, hormones, and many other contaminants. Even bottled water is not a guarantee for a worry-free product.

This is repeatedly shown by tests from consumer protection organizations such as Ökotest, Stiftung Warentest, or various consumer protection formats on television. The greatest safety for pure water is provided by further filtration of the drinking water directly at the point of extraction.