How much water should you drink a day? Estimate your needs
Hydration plays a role in temperature regulation, nutrient transport and kidney function. But there is no single figure that applies to everyone.
Health authorities publish reference values for total water intake, meaning all sources combined: drinks and food. Anses and EFSA use as a benchmark around 2.0 L a day for an adult woman and around 2.5 L a day for an adult man, in moderate temperature and activity conditions.
This calculator gives an indicative range built from those reference values. It is not medical advice and does not replace a health professional.
Your indicative estimate
Enter your profile: the range shown starts from Anses and EFSA reference values, adjusted indicatively for activity, heat and pregnancy or breastfeeding.
1.8 – 2.3 L
All sources combined, drinks and food, per day.
1.2 – 1.8 L
Roughly 70 to 80 % of total intake: the rest comes from food.
Assumptions used
- Female
- 19 to 50 years
- Low
- Temperate conditions
Indicative estimate, not medical advice. Real needs vary from one person to another.
Sources: Anses, opinion on dietary reference values for water, and EFSA, dietary reference values for water (2010).
What changes your needs
A reference value is a population benchmark, not an individual prescription. Several factors move the dial one way or the other.
Physical activity
Sweating increases losses of water and minerals. The longer and more intense the effort, the higher the needs, especially during prolonged exercise.
Heat and altitude
High heat, dry air or altitude increase losses, even without exercise. Heatwaves are particularly relevant for older people and young children.
Pregnancy and breastfeeding
Needs are slightly higher during pregnancy and higher still while breastfeeding. Usual medical follow-up remains the reference.
Food hydrates too
Roughly 20 to 30 % of total water intake comes from food: fruit, vegetables, soups, dairy. The amount to cover with drinks is therefore lower than the total reference value.
Worth keeping in mind
These benchmarks apply to healthy adults in usual conditions. They do not transfer as such to infants, to people with fever or dehydration, or to extreme exertion.
With kidney disease, heart failure, diuretic treatment, a complicated pregnancy or simply any doubt, water intake should be discussed with a doctor, who may recommend a very different amount.
Neither too little nor too much. Drinking very large amounts in a short time can dilute blood sodium and cause hyponatraemia, which is dangerous. This calculator encourages no extreme intake.
Nothing on this page is a diagnosis or a treatment. If you have symptoms, consult a health professional.
Frequently asked questions
Go further
Which water should you drink?
A few questions to identify the type of water that suits your profile and preferences.
Treating tap water
The full guide to options for improving the taste and quality of water at home.
Filter pitcher comparison
What pitchers really change, their limits and their running cost.
Water quality by municipality
Official analyses of the network supplying your home.