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Keeping hydrated

You can’t survive without water. It makes up nearly two-thirds of your body and is essential for you to function properly. Water has a wide range of benefits for your body – everything from removing waste products in urine to lubricating your joints. It can even make your skin look good.

Here, we explain why you need to drink enough and offer some tips to help you stay hydrated.

Glasses of water with fruit

How much should I drink?

As a basic guide, most people need about 1.5 to 2 litres of fluid a day, which is about eight to 10 glasses.

You can get this from water and other drinks, such as milk and fruit juice. Water in food also counts – fruit and vegetables contain lots of water. Cucumber and lettuce have the highest water content of any food – a massive 96 per cent. Tomatoes are also packed with water – they’re about 95 per cent water. Just adding some salad to a sandwich can top your hydration levels up.

The exact amount of fluid you personally need can depend on things like:

  • your age – this affects how well your body can balance water and salts; and as you get older, you store less water
  • your gender – men need more water than women because women have a higher proportion of body fat
  • the amount of physical activity you do – you need to drink more if you exercise more
  • the climate – you need to drink more if it's hot and you're sweating water out of your body
  • if you’re pregnant – you’re more likely to develop constipation during pregnancy so you need to drink more
  • your diet – if you’re following a special diet or very low-calorie diet, you may need to drink more but ask a dietitian for advice

What should I drink?


Water is the best choice when it comes to meeting your body's needs for fluids. It doesn't have any calories and is free if you drink tap water.

If you find plain water unappealing and want a tastier drink, then squash, milk, fruit juices or teas will also top up your fluid level. It's a trade-off though, because these contain calories, usually from sugar, and they can damage your teeth.

One way to make water more exciting is to add slices of lime, orange or lemon. Cucumber is also nice. It gives the water a fragrance and taste that makes it much more interesting. It’s healthy, hydrating and homemade.

Coconut water

Coconut water is a popular drink these days and is another option for topping up your fluid levels. It contains the mineral potassium, as well as sodium and natural sugars. It's sometimes used to replace lost fluids to treat dehydration. It's also been reported to contain antioxidants. But remember those sugars, so don't drink too much of it.

Fruit juice and smoothies

Fruit juices and smoothies contain lots of vitamins. One glass (150ml) can make up one of your five portions of fruit and vegetables a day. But the downside is, they contain lots of sugar and can be acidic, both of which are bad for your teeth. Because of this, it’s best to limit how much fruit juice you drink and to have it with a meal. You can read more in our blogs: How to spot sugary foods and protect your teeth and Acid erosion and your teeth.

One way to dilute all that sugar is to blend fruits with water or ice.

Smoothies and juicing

Here are some top tips on how to make smoothies.

  • Use crushed ice to thicken your smoothie rather than using yoghurt or milk.
  • Water-rich fruits include grapes, watermelon, kiwi and oranges, so these are good to add to your mix.
  • Water-rich vegetables for your green juices could include iceberg lettuce, cucumber and celery.
  • You can also use herbal teas in your juices and smoothies – peppermint works well.

Fizzy drinks

Fizzy drinks and squashes can contain more calories and sugar than you would imagine. Some fizzy drinks contain a whopping nine teaspoons – 35g – of sugar. If you still decide to go for these, choose squashes with ‘no added sugar’ on the label or low-calorie versions of fizzy drinks.


Milk is a good choice because it contains nutrients such as protein, B vitamins and calcium as well as being a source of water. Be careful how much you drink because it can also contain saturated fat. Choose semi-skimmed or skimmed options.

If cow's milk doesn't agree with you, soya, rice and almond milk are alternative options. Some are fortified with calcium to ensure you don't miss out on this vital nutrient.

Tea and coffee

Tea, the nation's favourite, and coffee also contribute to your fluid intake. Both contain caffeine, which is a mild diuretic so they can increase the amount of urine you produce. But if you drink caffeinated drinks in moderation, you shouldn’t need to drink extra fluid to compensate for this. Limit yourself to no more than 400mg of caffeine a day, which is about four to five cups of coffee or nine cups of tea a day.

If you’re pregnant, have less (two cups of coffee or four cups of tea). As an alternative, you could try herbal teas or decaffeinated versions.

It’s also important to remember that fizzy drinks and energy drinks can contain a lot of caffeine. Check the label and add these to your count so you don’t go over the recommended limit of caffeine.

Does alcohol count?

Although technically, alcoholic drinks contain water, they’re also diuretics and make you lose water from your body as urine. You can get dehydrated if you drink too much alcohol, so drink water or other soft drinks alongside alcohol. Remember to drink sensibly.

Is bottled best?

Nutritionally, bottled water is barely different from tap water. Tap water is safe to drink in the UK. But 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. Make sure the cap is sealed, and don’t add ice unless it’s made from bottled water.

Why is water important?

It’s really important to stay hydrated. Your body uses water to help with lots of processes, such as:

  • transporting nutrients and oxygen around your body
  • getting rid of waste products
  • controlling your temperature
  • keeping your joints lubricated so they act efficiently as shock absorbers

If you drink enough water, it will also help to keep your skin healthy.


It’s important to keep your body’s water content topped up, otherwise you might develop dehydration, which is a lack of water in your body. This can happen when you lose more water than usual – for example, if you have a bout of vomiting or diarrhoea or don’t drink enough. Other ways you can get dehydrated include sweating a lot and drinking too much alcohol.

So, how can you tell if you're dehydrated or not? If you feel thirsty, chances are your body’s telling you that you need to drink more. But the best indicators are the number of times you go to the toilet and the colour of your urine – it should be pale yellow. If you don’t need to go often, you only pass a little each time and it's dark in colour, it’s likely that you’re dehydrated. Other signs include:

  • a headache
  • feeling tired, weak and dizzy
  • feeling confused
  • dry mouth and lips
  • cramp

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

Image showing hydration level by urine colour

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, the best way to hydrate is by drinking water. That may be all you need. It’s better to drink little and often rather than trying to drink a lot all in one go because this may make you vomit.

If you have more serious dehydration that’s caused by diarrhoea or vomiting, you’ll also be losing important salts and sugars from your body. A good way to replace these is with rehydration sachets, which you add to water. Some people choose sports drinks but these contain much more sugar than you need so it’s best to stick to rehydration sachets.

If you have more severe dehydration, ask your pharmacist or GP for advice. You may need to go to hospital to be given fluids through a drip.

Can you drink too much water?

You might have heard stories about people drinking too much water and it's certainly possible. Drinking too much water isn't good for you and can even be dangerous (although it rarely is). The reason why is that it can cause the level of salt in your blood to drop too low – a condition called hyponatraemia.

A good way to gauge if you're drinking too much is to check how often you're going to the toilet. If you're going lots and your urine looks really pale, you might be drinking more than you need.


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  • Other helpful websites Other helpful websites

    Further information


    • Healthy hydration guide. British Nutrition Foundation., revised January 2016
    • Fluid. British. Dietetic Association., published March 2017
    • Skin health. British Dietetic Association., published April 2016
    • National nutrient database for standard reference release 28. Basic report: 11252, lettuce, iceberg (includes crisphead types), raw. United States Department of Agriculture., revised May 2016
    • National nutrient database for standard reference release 28. Basic report: 11205, cucumber, with peel, raw. United States Department of Agriculture., revised May 2016
    • National nutrient database for standard reference release 28. Basic report: 11529, tomatoes, red, ripe, raw, year round average. United States Department of Agriculture., revised May 2016
    • Hooper L, Abdelhamid A, Attreed NJ, et al. Clinical symptoms, signs and tests for identification of impending and current water-loss dehydration in older people. Cochrane Database of Systematic Reviews 2015, Issue 4. doi:10.1002/14651858.CD009647.pub2
    • Common problems in pregnancy. PatientPlus., last checked 5 May 2016
    • Personal communication, Mr Paul McArdle, Registered Dietitian, 13 November 2017
    • USDA branded food products database. Full report (all nutrients): 45154316, pure coconut water with coconut pulp, UPC: 853883003152. United States Department of Agriculture., revised May 2016
    • Pediatric dehydration. Medscape., updated 7 December 2016
    • Kalman DS, Feldman S, Krieger DR, et al. Comparison of coconut water and a carbohydrate-electrolyte sport drink on measures of hydration and physical performance in exercise-trained men. J Int Soc Sports Nutr 2012; 9(1):1. doi:10.1186/1550-2783-9-1
    • Caring for teeth. Oral Health Foundation., accessed 23 October 2017
    • Childhood obesity: a plan for action. GOV.UK., updated 20 January 2017
    • Soft drinks industry levy: 12 things you should know. GOV.UK., published 18 August 2016
    • Maintaining a healthy weight and preventing excess weight gain among adults and children. National Institute for Health and Care Excellence (NICE), 13 March 2015.
    • National nutrient database for standard reference release 28. Basic report: 01083, milk, lowfat, fluid, 1% milkfat, with added nonfat milk solids, vitamin A and vitamin D. United States Department of Agriculture., revised May 2016
    • Is fruit juice a healthy drink for children? British Nutrition Foundation., published 11 November 2014
    • Non-nutrient components of food. Oxford handbook of nutrition and dietetics (online). Oxford Medicine Online., published January 2012
    • NAA EFSA NDA Panel (EFSA Panel on Dietetic Products). Scientific opinion on the safety of caffeine. EFSA Journal 2015; 13(5):4102. doi:10.2903/j.efsa.2015.4102
    • National nutrient database for standard reference release 28. Basic report: 14411, beverages, water, tap, drinking. United States Department of Agriculture., revised May 2016
    • National nutrient database for standard reference release 28. Basic report: 14555, water, bottled, generic. United States Department of Agriculture., revised May 2016
    • Food and water precautions. Fit for Travel., accessed 21 November 2017
    • Dehydration. Medscape., updated 27 November 2016
    • Assessment of altered mental status. BMJ Best Practice., last updated 25 September 2017
    • Homeostasis. Oxford handbook of geriatric medicine (online). Oxford Medicine Online., published July 2012
    • Viral gastroenteritis. BMJ Best Practice., last updated 3 June 2016
    • Diarrhoeal diseases. Oxford handbook of tropical medicine (online), (updated). Oxford Medicine Online., published January 2014
    • Hyponatraemia. PatientPlus., last checked 22 March 2016
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    Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, November 2017
    Expert reviewer, Mr Paul McArdle, Registered Dietitian
    Next review due November 2020

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