How Much Water Should You Drink Each Day?

How much water should you drink? There is no single number that suits everyone, but a common guideline is around 1.5 to 2 litres of fluid a day for many healthy adults, and a little more in hot weather or when you are active. Your thirst, the colour of your urine and your daily routine are better guides than a fixed rule.

General information only: This article is general information, not medical advice. If you have kidney, heart or other health conditions, take medication that affects fluids, are pregnant or breastfeeding, or are caring for a baby or elderly person, ask a doctor how much you should drink.

Where the “eight glasses” idea comes from

When people ask how much water should you drink, the usual answer is eight glasses a day. It is an easy rule to remember, and it lands near the commonly cited range, but it is not a scientific law. Your needs depend on your body size, climate, diet and activity level.

It also helps to know that water is not the only source of fluid. Tea, coffee, milk, juice, soup and even fruit and vegetables all contribute to what your body takes in. A good portion of daily fluid, often around a fifth, comes from food.

What affects how much you need

• Heat and humidity. You sweat more in warm weather and need to replace what you lose.
• Exercise. Longer or harder sessions increase fluid loss.
• Body size. Larger bodies generally need somewhat more.
• Diet. A diet rich in fruit, vegetables and soups provides more fluid than one built on dry, salty snacks.
• Illness. Fever, vomiting or diarrhoea can lead to fast fluid loss.
• Pregnancy and breastfeeding. Both usually increase the need for fluid.
• Altitude. Higher places can increase fluid loss through breathing.

How much water should you drink? General guidance at a glance

Health authorities give slightly different figures, and they describe total fluid from drinks, not just plain water. The numbers below are approximate and are meant as a rough starting point only.

Group	Approximate daily fluid from drinks
Adult women	About 1.5 to 2.2 litres
Adult men	About 2 to 3 litres
Children	Less, depending on age and size
Hot weather or heavy exercise	More than usual
Pregnancy or breastfeeding	Usually more, ask your doctor

If these figures seem very different from what you drink now, do not panic. Plenty of people feel well on less, as long as they are healthy, not thirsty and their urine is a pale colour.

Simple ways to tell if you are drinking enough

Check your thirst

For most healthy people, thirst is a reliable answer to how much water should you drink. Drink when you feel thirsty, and make sure you have water within reach. Older adults sometimes notice thirst less, so they may need to drink on a schedule.

Look at the colour of your urine

Pale yellow, like straw, is generally a good sign. Darker yellow or amber can suggest you need more fluid. Certain foods, vitamins and medications can change colour, so treat it as one clue and not a verdict.

Notice how you feel

Mild dehydration can bring a dry mouth, tiredness, headache or difficulty concentrating. These symptoms have many other causes too, so if they last, speak to a doctor.

Easy ways to drink more through the day

If you tend to forget, a few small habits make a big difference.

1. Start the day with a glass of water before your first coffee.
2. Keep a bottle on your desk or in your bag, and refill it whenever it is empty.
3. Drink a glass with each meal.
4. Add a slice of lemon, cucumber or mint if plain water feels boring.
5. Eat water-rich foods such as oranges, cucumber, tomatoes and melon.
6. Link drinking to existing habits, such as every time you finish a call or return from a walk.

Water is also the cheapest drink there is, which makes it a natural fit for anyone eating healthily on a budget. And if you take regular walks, our guide to walking for fitness has tips on staying comfortable on longer outings.

Can you drink too much?

It is uncommon, but possible. Drinking very large amounts of water in a short time can dilute the body’s sodium levels, a condition called hyponatraemia. It is mostly a concern during extreme endurance events or with certain medical conditions. For everyday life, drinking steadily and responding to thirst is enough.

Caffeinated drinks do count towards your fluids, although very large amounts of caffeine can have other effects. Alcohol, on the other hand, tends to make you lose more fluid, so it is a poor choice for hydration.

Once you have answered how much water should you drink, remember hydration is only one piece of daily wellbeing. Poor sleep and stress also change how you feel, so you may find our sleep guide useful too. You can browse more everyday advice in the health section.

Frequently asked questions

Further reading: Wikipedia overview: Drinking water.