The amount of water a person should drink daily varies by factors such as sex, activity level, climate, and health. For average healthy adults, the general recommendations are about 3.7 liters (15.5 cups) per day for men and 2.7 liters (11.5 cups) per day for women. This includes all fluids consumed from water, other beverages, and food moisture. The common advice of drinking eight 8-ounce glasses (about 2 liters) daily is a reasonable goal but may be insufficient or excessive depending on individual circumstances. Active people, those in hot climates, pregnant or breastfeeding women, and people with certain health conditions may need to drink more than the average amounts to stay hydrated. Thirst is also a good indicator of when to drink water. The European guideline sets a somewhat lower total intake of around 2 to 2.5 liters per day for adults. About 20% of water intake typically comes from food, and the rest from drinks. Daily fluid loss occurs through urine, sweat, breathing, and bowel movements, which must be replenished. In summary:
- Average men: about 3.7 liters/day total water
- Average women: about 2.7 liters/day total water
- Adjust based on activity, environment, health, and life stage
- Follow thirst cues and drink more when sweating or in hot weather
These recommendations include all fluids, not just plain drinking water.
