How Much Water Should You Drink a Day? (It's Not Always 8 Glasses)
What the National Academies say about daily water for women and men, how much more to drink when you exercise or it's hot, whether tea and coffee count, and easy ways to drink more.
By the TurantTools Health team · Updated October 19, 2026 · 4 min read
“Drink 8 glasses a day” is the advice almost everyone has heard. It isn't wrong, but it isn't the whole story either. Here's what the experts actually say, and how to work out a number that fits your day.
What the experts say
The US National Academies set an adequate intake of total water of about 2.7 litres a day for women and 3.7 litres for men. That includes the water in food, which gives roughly a fifth of it. So the drinking part is about:
- Women: about 2.2 litres (74 fl oz), or 9 glasses of 250 ml
- Men: about 3 litres (101 fl oz), or 12 glasses of 250 ml
So for many women, 8 to 9 glasses is about right. Many men need a few more.
Exercise and hot weather
You lose more water when you sweat. A simple rule our calculator uses is about 0.3 litres extra for every 30 minutes of exercise, and half a litre more on a hot day.
Drinks a day (litres)
| Your day | Litres | Glasses |
|---|---|---|
| Woman, no exercise | 2.2 | 9 |
| Woman, 30 min exercise | 2.5 | 10 |
| Woman, 60 min, hot day | 3.3 | 13 |
| Man, no exercise | 3 | 12 |
| Man, 30 min exercise | 3.3 | 13 |
| Man, 60 min, hot day | 4.1 | 16 |
Do tea and coffee count?
Yes. All drinks count towards your daily water, and so does water-rich food like fruit, vegetables and soup. Water is still the best everyday choice because it has no sugar.
Easy ways to drink more
- Have a glass with every meal: that's three already.
- Keep a bottle where you can see it, on your desk or in your bag.
- Drink a glass when you wake up and one mid-afternoon.
- Add lemon, cucumber or mint if plain water feels boring.
- Use pale yellow urine as your guide: dark yellow means drink more.