Daily Water Requirement
How much water to drink a day: EFSA references and weight
Quick answer
EFSA sets an adequate intake of total water of 2.5 L/day for men and 2.0 L/day for women (drinks + food, in moderate conditions). An alternative weight-based estimate is 30–35 mL/kg per day. Needs rise with heat, physical activity, fever and breastfeeding.
| Reference | Total water/day |
|---|---|
| EFSA — adult men | 2.5 L |
| EFSA — adult women | 2.0 L |
| Weight-based | 30–35 mL/kg |
How it is calculated
The EFSA (2010) values are adequate intakes (AI) for total water, which includes the water in food (about 20–30%). The 30–35 mL/kg estimate is a practical clinical rule of thumb for adult maintenance.
Around 80% of total water usually comes from drinks and the rest from food, so the water you actually drink is generally lower than the total-water values shown.
Factors that increase needs
Increase intake with hot weather, intense physical activity, fever, breastfeeding and pregnancy. People with a high energy expenditure often have higher water needs too: see the TDEE, the macronutrient split and the protein requirement.
Disclaimer
These estimates are indicative and for information only. With kidney or heart conditions or therapies requiring fluid restriction, follow your doctor's guidance: this tool does not replace professional advice.