Determining how much water you should drink each day to achieve maximum health benefits may not be as simple as you think. Your need for water depends on a variety of factors, including your level of activity, your health, and where you live.
If you perform any type of physical activity that causes you to perspire, it’s important to increase your water intake. Depending on how much you sweat, how long you exercise, and what type of activity you perform, the fluid loss will vary greatly. In addition, if you’re in a hot or humid environment, you will find yourself in need of more fluid to compensate for additional loss of fluids through sweat or even through your skin losing moisture.
Other factors that determine your required water intake are illness and pregnancy or breast-feeding. Fever, vomiting, and diarrhea cause your body to experience fluid loss. Conversely, heart failure and some types of adrenal, kidney, and liver diseases might require you to reduce your fluid intake. Pregnant women or women who are breast feeding need to remain hydrated and should increase their fluid intake significantly.
The rule of thumb for liquid intake is to drink eight 8-ounce glasses of water a day. There are also other schools of thought that encourage a replacement approach, where you should consume about 2 liters of water a day to replace the fluids you lose through urination and breathing, sweating, and bowel movements. Alternatively, the Institute of Medicine recommends that men drink about 3 liters of total beverages a day and that women drink about 2.2 liters. In the end, however, as long as you drink enough liquids so that you don’t really feel thirsty and are able to produce 1.5 liters of colorless or slightly yellow urine a day, you’re likely consuming an adequate amount of fluids.