How much water should I drink a day?

Your water needs based on EFSA guidance, with additions for exercise and heat – in litres and glasses. No sign-up.

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1.4–1.6 L

≈ 6 glasses of 250 ml

EFSA: ~2.0 L of water a day in total – food included.
Of that, ~1.4–1.6 L from drinks (the rest comes from food: soups, vegetables, fruit).

For comparison: the popular “30–35 ml per kg” rule would give you 2.1–2.5 L. That's a rule of thumb, not an EFSA recommendation.

Where these numbers come from

EFSA (the European Food Safety Authority) gives adults an “adequate intake” of about 2.0 L of total water a day for women and 2.5 L for men.
In pregnancy EFSA adds about 0.3 L, when breastfeeding about 0.7 L.
Food usually provides about a fifth to a quarter of your water, so drinks make up 70–80 % of the total.
For exercise we add 0.4–0.8 L an hour, for heat 0.5–1 L. These are rough additions – sweating varies a lot from person to person.

Forget to drink? The Dumpli app has a water tracker – tick off glasses and see how many are left, with reminders if you want them. It's still in testing and invite-only – join the waitlist.

See the app Water guide

How we calculate

The base is EFSA's "adequate intake": about 2.0 L of total water a day for adult women and 2.5 L for men. It's a guide, not a strict rule, and it covers more than water from a glass: tea, coffee, soups, fruit and vegetables all count. Because food provides part of it, drinks make up 70–80 % of the total.

For exercise and heat we add rough amounts: 0.4–0.8 L per hour of exercise and 0.5–1 L on a hot day. People sweat very differently, so treat these as a guide only.

How to tell you're drinking enough

Urine colour: pale yellow is usually fine; dark means it's worth having a drink.
Thirst: for a healthy adult it's usually a good guide. Older people often feel it less, so a habit helps – a glass with every meal.

More in how much water to drink a day (what counts, when you need more and when to check with a doctor) and nutrition for seniors.

Check with your doctor first about how much to drink if you have kidney or heart disease, take water tablets (diuretics), are very thirsty and passing urine often, or are losing fluids through long-lasting vomiting or diarrhoea. In an emergency (confusion, fainting, hardly passing urine) call your local emergency number.

Frequently asked questions

How much water should I drink a day?

The European Food Safety Authority (EFSA) gives adult women about 2 litres and men about 2.5 litres of water a day in total, food included. From drinks that's usually 1.4–1.6 L for women and 1.8–2 L for men, more when you exercise or it's hot.

Is it true you need 30 ml per kg of body weight?

It's a popular rule of thumb, not an EFSA recommendation. The calculator shows it for comparison only. For larger people it gives more than is usually needed, so we use the EFSA figures as the base.

Do coffee and tea count?

Yes, coffee, tea, milk and soups all count towards your fluids. Don't count alcohol. More in the water guide.

How much water do I need when pregnant or breastfeeding?

EFSA adds about 0.3 litres a day in pregnancy and about 0.7 litres when breastfeeding. If you have questions, ask your doctor or midwife.

Why is there no number for kidney or heart disease?

In those cases doctors sometimes limit fluids, and a general number could do harm. Please follow your doctor's advice.