When does your body need more water?
In usual circumstances women need at least 2 and men 2.5 liters of fluid daily. In some situations, in case of increased water loss from the body, the need can be significantly bigger.
Sweat excretion during physical activity and high air temperature depend on intensity and length of muscular work, clothes, motion and air humidity. During physical activity a person can excrete less than 0.5 l of sweat per hour, in average 1 to 2 liters, while some excrete more than 3 liters per hour. Laborers working in high air temperatures may need even 12 liters of fluid daily. In the process, a lot of salt is lost from the body, according to some studies it reaches 10 – 15 gr a day. In cases like these, intensive fluid and mineral replacement is needed.
Increased cold and air dryness also lead to bigger water loss from the body. When it’s cold, we urinate more often, and in that way more water is lost through urine. When the air is dry, more water is lost by water vapor during breathing. This is important in hiking because at higher altitudes we breathe faster due to lower oxygen concentration in the air. Hikers at high mountains may need up to 7 l of water per day.
Airline passengers flying many hours can also be mildly dehydrated, because of air dryness in the cabins. That’s way it’s recommended to drink a glass of water more for every hour on the flight. Using air conditioners during flight can also contribute to change in air humidity in closed spaces, so we shouldn’t forget about fluid intake.