How much water should you drink a day?

What the guidelines say

EFSA suggests about 2.0 L of water a day for women and 2.5 L for men, at moderate temperature and activity.¹ That’s total water: what you drink and what comes with your food.

In the US the numbers are a bit higher, 2.7 L for women and 3.7 L for men, also counting food.² Neither is wrong: they were worked out with different populations.

When you need more

In the heat, when you exercise, during pregnancy or while breastfeeding, your body asks for more. If you train, a sports guideline suggests starting with 0.4 to 0.8 L an hour and adjusting to how much you sweat.³

In the app, when Apple Health tells me you worked out, I add glasses to your day’s goal, no math needed.

Easy signals

Thirst is a good guide for most healthy people. Another simple signal is the color of your urine: pale is fine, very dark is asking for water.

Coffee, tea, milk and herbal teas also add fluid to your day. What I don’t count as water is alcohol.

Can you drink too much water?

For a healthy person it’s rare. Drinking very large amounts in a short time, for example during a long race, can lower the sodium in your blood too much. That’s why it’s better to drink by thirst than to force yourself to hit a number.