How much water should adults drink daily?

Short answer
- A common, simple target is about 2–3 liters (8–12 cups) of total beverages per day for most adults.

More accurate guidance
- U.S. Institute of Medicine (IOM/NASEM) adequate intakes for total water (all beverages + water in food): about 3.7 L/day for men and 2.7 L/day for women.
- That includes roughly 20% of water coming from food, so beverages alone are typically ~3.0 L (men) and ~2.0–2.2 L (women).
- European recommendations are similar (about 2.5 L/day for men and 2.0 L/day for women, total water).

Practical rules and signs you’re drinking enough
- “Drink to thirst” works for most healthy adults.
- Aim for urine that is pale yellow (very dark = drink more).
- Increase intake during hot weather, heavy exercise, fever, vomiting/diarrhea, pregnancy or breastfeeding, and at high altitude.

Exercise and special situations
- For moderate exercise, add 0.4–0.8 L/hour of activity (more for intense/prolonged exercise). Consider electrolyte-containing drinks for long, hard workouts or heavy sweating.
- Older adults may need reminders to drink because thirst can decrease with age.

Caution
- Overdrinking very large amounts quickly can cause hyponatremia (low blood sodium). Don’t force excessive water intake beyond your needs or medical advice.
- If you have kidney, heart, or certain other medical conditions, follow specific fluid recommendations from your clinician.

If you want, tell me your age, sex, activity level, and climate and I can give a more personalized estimate.