Good afternoon. It must be remembered that such a volume of liquid is recommended for an adult of about 70 kg of weight, who is in a room with 60-80% humidity and a comfortable 22-23 degrees Celsius indoors.
The daily volume is different for each person. During the summer, fluid intake may be higher. In conditions of cold air and lack of physical stress - lower.
Accordingly, children have their own volume of needs, people who are obese or thin have their own.
Take care of yourself and your health.
To the first answer, I want to add that the amount of water needed for a person is really individual, because much depends on what kind of load you have. If you go to the gym or work is connected with physical labor, then of course you need more water than a person who sits on the couch all day. Also, we are all different physiques. By the way, coffee and tea lower the water balance. We are 80% water, so it's better not to neglect it.
There is no scientific evidence for the need for 2 liters per day, all this is very individual and it is very difficult to say specifically the general figure. Men need a little more water than women, and requirements change with age. Where these 2 liters came from is unclear. You need to find a unique formula for yourself. And keep in mind that soups, fruits, vegetables, etc. also contain liquid, and this also counts. Also, the body can take the feeling of thirst for a feeling of hunger and instead of drinking you will go to eat. To avoid this, before each meal, drink a glass of water (30-40 minutes) and then you do not get confused. Avoid mineral water, they should be drunk only in courses or as directed by a doctor. About purchased juices and colas, and I am not talking at all