How much should you drink per day?
Every day you lose water through your breath, perspiration, urine and bowel movements. For your body to function properly, you must replenish its water supply by consuming beverages and foods that contain water.The Institute of Medicine determined that an adequate intake (AI) for men is roughly about 13 cups (3 liters) of total beverages a day. The AI for women is about 9 cups (2.2 liters) of total beverages a day. "Drink eight 8-ounce glasses of water a day."
That's about 1.9 liters, which isn't that different from the Institute of Medicine recommendations. Although the "8 by 8" rule isn't supported by hard evidence, it remains popular because it's easy to remember. Just keep in mind that the rule should be reframed as: "Drink eight 8-ounce glasses of fluid a day," because all fluids count toward the daily total.