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

Interesting words

  • Hydration – the process of adding the required amount of water to your body.
  • Dehydration – when the body does not have enough water to function fully.
  • Water content – the amount of water in something. For example, how much water is present in food.

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.

How much water should we drink?

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.

We should aim to drink six to eight glasses of water every day.

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.

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.

Body functions and water

  • Eyes – water provides moisture to keep our eyes clear from irritation.
  • Kidneys – water helps our kidneys get rid of waste and toxins that our bodies do not need.
  • Body temperature – 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 – water plays an important role in our stomach, helping to digest food and transport nutrients around our body.
  • Muscles and joints – 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.

Close up of girl's eyes


Water provides moisture to keep our eyes clear from irritation.

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Test your knowledge with this short true or false quiz.


  • Measure out 6–8 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.