hydration · 1 min read
How many bottles of water should I drink a day?
How many bottles of water should I drink a day? There is no fixed number. Reference intakes of 2.7 L for women and 3.7 L for men include food and all beverages, which puts most people near four to six 500 ml bottles.
Written by Lifebar Desk · Checked against the sources listed below
Published 18 Jul 2026
Key takeaways
- Adequate intake is about 3.7 L a day for men and 2.7 L for women, including water from food and all drinks.
- Roughly 20% of daily water comes from food, and coffee and tea count toward the total.
- Pale straw-coloured urine is a practical everyday indicator of adequate hydration.
The eight-glasses rule has no clear origin in research. The actual reference values are higher, and they include things you do not think of as water.
The reference intakes
The National Academies set adequate total water intake at approximately 3.7 litres daily for adult men and 2.7 litres for adult women. Critically, this is total water, from plain water, all other beverages, and food.
Roughly 20% arrives in food. Soup, fruit, yoghurt, vegetables and even bread carry water. Coffee and tea count; the diuretic effect of caffeine at ordinary doses does not exceed the fluid delivered.
What that means in glasses
Subtracting food, most adults land at roughly 2 to 3 litres of drinks a day, more in heat, at altitude, during illness with fever, or with heavy exercise.
Better signals than counting
| Signal | Interpretation |
|---|---|
| Pale straw urine | Adequately hydrated |
| Dark amber urine | Drink more |
| Thirst | A functioning signal in healthy adults under 65 |
| Body weight drop after exercise | ~1 L per kg lost |
Thirst becomes less reliable with age, which is one reason dehydration is more common in older adults.
The overhydration risk
Drinking far beyond need dilutes blood sodium. Exercise-associated hyponatraemia has killed marathon runners who drank plain water on a fixed schedule. For events over about two hours, drink to thirst and include sodium.
Who needs a specific plan
Kidney stone formers, people with heart failure or chronic kidney disease, and endurance athletes all have intake targets that differ from the general advice, and all three should be individualised rather than guessed.
Frequently asked
Does coffee dehydrate you?
No. The mild diuretic effect is more than offset by the fluid volume. Moderate coffee contributes to daily hydration.
Can you drink too much water?
Yes. Exercise-associated hyponatraemia occurs when large volumes of plain water dilute blood sodium, and it can be fatal. Drink to thirst during long events and include sodium.
Sources
Educational content, talk to your clinician before changing treatment.
