How Much Water Should You Drink Every Day?
There is no single amount of water that suits everyone, but a common guide is about 2.7 litres of total fluids a day for women and 3.7 litres for men, including water from food and other drinks. Your own needs depend on your body size, activity, climate and health, and your thirst and urine colour are practical guides.
Where the “8 Glasses” Rule Comes From
The popular advice to drink eight glasses of water a day is an easy rule of thumb rather than a scientific requirement. The U.S. National Academies of Sciences, Engineering, and Medicine set adequate total water intakes of about 2.7 litres (women) and 3.7 litres (men) per day. These totals include all beverages and the water in food, which provides roughly 20 percent of intake for many people, so you do not have to drink all of it as plain water.
Why Your Body Needs Water
What Changes How Much You Need
- Hot weather or humidity: more sweat means more fluid loss
- Exercise: drink before, during and after
- Illness: vomiting, diarrhoea or fever increase needs
- Pregnancy and breastfeeding: need more fluid
- Altitude: may increase fluid loss
- Medical conditions: some need a limit, so ask your doctor
Signs You May Need More Water
- Thirst and a dry mouth
- Dark yellow urine and passing little urine
- Headache, tiredness or dizziness
- Dry skin or constipation
- Pale yellow urine
- Rarely feeling thirsty
- Steady energy through the day
Headaches can have many causes; see best ways to avoid migraines and insomnia.
Practical Ways to Drink Enough
Good hydration is one of many small habits that support health; see natural ways to improve overall health.
Can You Drink Too Much Water?
When to Ask a Doctor
If you have kidney disease, heart failure, liver disease or take medicines such as diuretics, your doctor may give you a specific fluid target, which you should follow. Seek help for signs of severe dehydration such as confusion, very little urine, a very fast heartbeat or fainting.
Want more everyday health tips?
Read more simple, pharmacist-checked guides on our health blog.
Visit the health blogFrequently Asked Questions
Does coffee or tea count towards fluid intake?
Yes, in moderate amounts they contribute to your total fluid intake.
Is thirst a reliable guide?
For most healthy adults, yes. Older adults and people exercising in the heat may need to drink on a schedule.
Does drinking more water help weight loss?
Replacing sugary drinks with water can help reduce calories, but water alone is not a weight-loss treatment.
More Reading
Sources: National Academies of Sciences, Engineering, and Medicine, “Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate”; U.S. Centers for Disease Control and Prevention (CDC) on water and healthier drinks; Mayo Clinic.