How much water should you drink per day? Get a personalized recommendation.
The National Academies of Sciences recommends approximately 3.7 liters (125 oz) of total daily water intake for men and 2.7 liters (91 oz) for women from all sources, including food. About 20% of daily water intake typically comes from food, especially fruits and vegetables. The remaining 80% should come from beverages.
The popular advice to drink eight 8-ounce glasses (64 oz) of water per day is a reasonable starting point for many people, but it is not based on rigorous scientific evidence. Actual needs vary significantly based on body size, activity level, climate, diet, and overall health. A 200-pound active male in a hot climate needs considerably more than a 120-pound sedentary female in a cool climate.
Thirst is a late indicator of dehydration. Earlier signs include dark yellow urine (aim for pale straw color), headache, fatigue, dry mouth, decreased urination, and difficulty concentrating. Even mild dehydration (1-2% body water loss) can impair cognitive function and physical performance.
Yes. Hyponatremia (dangerously low sodium levels from excessive water intake) is rare but can be serious, particularly in endurance athletes who drink large volumes without replacing electrolytes. For most healthy adults, the kidneys can process about 0.8-1.0 liters per hour. There is no need to force excessive intake beyond thirst and urine color guidelines.