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Why do we need to drink water?

Water is essential to life and can be found in all living things. Find out why we need to include water in our diet.

In this article you can learn:

  • why we need to drink water
  • how much water we should drink
  • what hydration and dehydration mean
  • signs of dehydration
  • where we can get water from

This resource is suitable for Health and Wellbeing for primary school learners.

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Video - Why do we need water?

In this video, the Great Spoon explains why we need water in our diets and how much water is in different kinds of food.

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Key words about water

  • 鈥 The process of adding the required amount of water to your body.
  • 鈥 When the body does not have enough water to function fully.
  • 鈥 The amount of water in something. For example, how much water is present in a piece of food.
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Why do we need water?

Our bodies are made up of more than 60% water. That is more than half of our body weight.

Our bodies are constantly losing water through:

  • sweating
  • going to the toilet
  • breathing

To remain healthy and avoid dehydration it is important to replace this lost water throughout the day.

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How much water should we drink?

Eight glasses of water and a jug pouring water into one glass
Image caption,
According to NHS guidelines, we should aim to drink six to eight glasses of water every day. (L A Heusinkveld / Alamy Stock Photo)

NHS guidelines advise drinking around six to eight glasses a day.

Our bodies lose more water than usual if we are very active or when the weather is particularly warm, because we sweat more. Before, during and after exercise we benefit from drinking water and eating foods with a high water content. This helps us to perform better and keeps replacing the water lost. Athletes need to stay hydrated to get the most out of their bodies.

Eight glasses of water and a jug pouring water into one glass
Image caption,
According to NHS guidelines, we should aim to drink six to eight glasses of water every day. (L A Heusinkveld / Alamy Stock Photo)
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Where can we get water from?

It is good for our health to eat foods that have a high water content, like fruit. For example, peaches, oranges and strawberries are all full of water, as well as nutrients.

Vegetables are also great at keeping us hydrated as they too have a high water content. Cauliflower and cabbage are good examples.

All drinks contain water (such as tea, milk and fruit juice) and help add to our daily intake. However, water is the healthiest option as it quenches our thirst and will not damage our teeth.

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Signs of dehydration

If we do not drink enough water, our bodies become dehydrated.

  • We can feel tired
  • Our skin and lips become dry
  • We might get a headache
  • Our urine is darker in colour
  • We go to the toilet less often

We generally start to feel unwell as we need water to carry out lots of important bodily functions.

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Body functions and water

  • Eyes 鈥 water provides moisture to keep our eyes clear from irritation.
  • Kidneys 鈥 water helps our kidneys get rid of waste and toxins that our bodies do not need.
  • Body temperature 鈥 water allows our body to get rid of excess heat as sweat. This regulates our body temperature and stops us from getting too hot.
  • Digestive system 鈥 water plays an important role in our stomach, helping to food and transport around our body.
  • Muscles and joints 鈥 muscles are mostly water and water also cushions joints allowing them to move smoothly.

Find out more about our body systems with 2nd level Science on Bitesize.

Image gallerySkip image gallerySlide 1 of 5, Close up of girl's eyes, Eyes Water provides moisture to keep our eyes clear from irritation.
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Test your knowledge

Test your knowledge with this short true or false quiz.

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Challenge - How much water do we need?

  • Measure out 6鈥8 glasses of water
  • If you have a reusable water bottle, investigate how many times you would need to fill it and drink it a day to get the recommended amount of water. It depends on the volume of water your bottle holds.
  • Make a list of your favourite foods and look up their water content. You can find the water content listed on food and drink labels or by researching foods, like fruit and vegetables, online.
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