According to a National Institutes of Health report, about 60 percent of the average human body is made of water, which includes most of your brain, heart, lungs, muscles, and skin, and even about 30 percent of your bones. The common philosophy is to drink eight 8-ounce glasses of water per day or about two liters, but scientists say that it’s not necessary. Many studies recommend that we don’t need nearly this much water, and scientists have yet to come to a consensus on what the absolute amount of water to drink is.
The suggestion overlooks the fact that people also get water from the food they eat and the other beverages that they drink. All the food that we eat comprises of varying amounts of water, and previous studies show that the average person receives 20 percent of his or her daily water through the intake of food. Other beverages like coffee, soda, and juice also contribute to water intake.
The National Academies of Science said: “The vast majority of healthy people adequately meet their daily hydration needs by letting thirst be their guide.” They suggest that women approximately consumes a total of 2.7 liters of water from all the beverages and foods each day and that men approximately get 3.7 liters daily. But these are just general guidelines and are not supported by firm scientific studies. Although the amount of water to drink each day is important, equally important is the quality of drinking water.
As much as water you lose during sweating, the more water you’ll need to replace with food and drink. So, naturally, more water would be needed to drink for a person doing strenuous physical work in a hot, tropical climate than a person who has identical weight and height and spent the day sitting in an air-conditioned office.
The bottom line: Drink up when you feel thirsty and drink more when you sweat more.