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Keeping hydrated

You can’t survive without water. It makes up over half of your body and is essential for you to function properly. This article explains how to stay hydrated and why it’s so important.

Why is water important?

Your body uses water to help with many different processes, including:

  • transporting nutrients and oxygen around your body
  • getting rid of waste products
  • controlling your temperature
  • the function of your digestive system

Drinking enough water will also help to keep your skin healthy.

How much should I drink?

How much fluid you need depends on many factors including your age, diet, the amount of physical activity you do and the climate. As a basic guide, most people need about 1.5 to 2 litres of fluid a day. This includes water contained within foods. You will need to drink more than this if the temperature is high or you’re exercising. If you’re pregnant, it’s important that you drink enough as you’re more likely to develop constipation during pregnancy.

You can get the fluid you need from water, other drinks, such as milk and fruit juice, and also from your food – in particular, fruit and vegetables contain a lot of water.

Bored of water?

Water is the best choice when it comes to reaching your daily fluid requirement. It contains no calories or sugar and it’s generally free.

You can also meet your daily fluid intake with alternatives such as squash, milk, fruit juices or teas. It’s important to remember though that these are more likely to contain calories – usually from sugar. Fruit juices contain lots of vitamins and one glass can make up one of your five portions of fruit and vegetables a day. However, they contain lots of sugar and can be acidic, both of which are bad for your teeth. Therefore, it’s best to limit how much fruit juice you drink and have it with a meal.

Fizzy drinks and squashes can contain lots of calories and sugar, and fizzy drinks are also very acidic. Choose squashes with ‘no added sugar’ on the label and try to keep fizzy drinks to a minimum.

Drinks that contain caffeine, such as tea, coffee and cola, also contribute to your fluid intake. Caffeine is a mild diuretic, which means it slightly increases the amount of urine you produce. However, as long as you only drink caffeinated drinks in moderation you don’t need to drink extra fluid to compensate for this.

Although alcoholic drinks contain water, they are also diuretics and can cause you to become dehydrated. Drink water or other soft drinks alongside alcohol and always stick within the recommended alcohol limits.

Is bottled best?

Bottled water is nutritionally no different from tap water. Tap water is safe to drink in the UK. However, if you’re abroad and unsure about the quality of the water or aren’t used to it, it’s usually best to stick to bottled water.


It’s important to keep your body’s water content topped up, otherwise dehydration can develop. This is a lack of water in your body that occurs when you lose more water than usual, such as through vomiting or diarrhoea, or you don’t drink enough, perhaps because you’re ill. Other causes for dehydration include sweating a lot or drinking too much alcohol.

So, how can you tell if you're dehydrated or not? One of the best indicators is the number of times you pass urine and its colour – it should be pale yellow. If you don’t need to go as often as usual, you only pass a small amount each time and it's dark in colour, it’s likely that you’re dehydrated. Other signs include:

  • having a headache
  • feeling tired and weak
  • confusion
  • mood swings
  • dry lips

Dehydration can be an extremely serious condition, especially for babies, children and older people. If you have severe dehydration, your body stops getting rid of waste products and you may develop kidney failure.

What should I do if I become dehydrated?

If you think you may be dehydrated, you need to rehydrate your body by drinking fluid. For mild dehydration, drinking water may be all that’s needed – it’s better to drink little and often rather than trying to drink a lot all in one go as this may make you vomit, meaning that you lose even more water.

If you have more severe dehydration caused by diarrhoea or vomiting, you will also be losing important salts and sugars from your body. Rehydration sachets, which you add to water or other drinks, are a good way of replacing these. Some people choose sports drinks but these contain much more sugar than you need so it’s best to stick to rehydration sachets.

For more severe dehydration, seek urgent medical advice from your GP or pharmacist. You may need to go to hospital to be given fluids through a drip.

Action points

Follow these top tips to keep yourself well hydrated.

  • Try to carry a bottle of water with you so that it’s constantly available.
  • Drink a glass of water with every meal.
  • Eat plenty of fruit and vegetables as they contain lots of water – aim for at least five portions a day.
  • If your job means you’re sitting at a desk all day, try to keep a glass of water next to you.
  • Drink a glass of water before you exercise, as well as during and after.


Produced by Polly Kerr, Bupa Health Information Team, September 2012.

For sources and links to further information, see Resources.

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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