How much water you should drink per day based on your weight, physical activity and climate. Recommendations based on EFSA and ACSM.
Your daily target
Each glass ≈ 250 ml. Spread your intake throughout the day; don't drink it all in the evening to avoid waking up at night.
Hydration affects thermal regulation, nutrient transport and cognitive and athletic performance. A 2% drop in body weight from dehydration already reduces performance.
General recommendations
EFSA (2010) recommends 2.5 L/day for men and 2.0 L for women, including water from food. The 35 ml per kg of body weight practical rule gives an individualised estimate. In hot climates or with intense exercise, push to 45-50 ml/kg.
During exercise
ACSM recommends 500 ml in the 2-3 h before training and 150-250 ml every 15-20 minutes during activities longer than 1 h. If you train more than 1 h with heavy sweating, add electrolytes (sodium especially). For sessions under 60 min, water alone is enough for most people.
Frequently asked questions
Is the 2-litre rule true?+
It's an approximation. EFSA recommends 2.5 L (men) and 2.0 L (women) total intake including water from food. The 35 ml/kg of body weight rule is more individualised.
Do coffee and tea count?+
Yes, they contribute to net hydration despite the mild diuretic effect. What doesn't count are sugary soft drinks and alcohol.