Every day you lose water through your breath, perspiration, urine and bowel movements.

The National Academies of Sciences, Engineering, and Medicine determined that adequate daily fluid intake is:

About 15.5 cups (3.7 liters) of fluids for men
About 11.5 cups (2.7 liters) of fluids a day for women

These recommendations cover fluids from water, other beverages and food. About 20 percent of daily fluid intake usually comes from food and the rest from drinks.