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Water

fluid; liquid; circulate; circulatory; lymph; digestive; urinary system; water; body; blood; urine; temperature; perspiration; sweat; skin; saliva; drink; caffeine; kidney; germs; chlorine; fluoride; spring water; mineral water; diuretic; tap water. ;

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Did you know that water is even more important than food to your body because - your body is mostly water?

Yes it's true!

waterMore than half of your body weight is water. Your body can't survive for more than a few hours without having a drink, even less if you live in a hot country or the weather is hot.

This doesn't mean that your body is like a glass that you fill with water. Your feet would get pretty soggy wouldn't they?

What it does mean is that water is the biggest part of all the fluids that travel round your body, and there is a lot of water inside your cells too. Even bones have a lot of water in them!

So what does your body do with all that water?

It moves as blood around all your body - most of your blood is water - and water is also in lymph which travels around your body.

  • waterBlood and lymph are the main ways the body gets food and oxygen to your cells and the way wastes get taken away - this is a very important job for water!! Blood and lymph also have special cells in them which fight infections - they are part of your immune system.
  • Water carries digestive enzymes (say dy-jest-iv enz-eye-mz) around your digestive system, so that your food can be broken up into all the bits your body needs.
  • All the stuff the body doesn't need has to get out of the body somehow. Some of it goes from the blood to the kidneys, which make urine (wee) - which is mostly water. Some stays in your gut and comes out as faeces (poo) - which is also mostly water! Some comes out in the air you breathe (if you breathe onto a really cold mirror you will see little drops of water on the glass - this is water from your breath).
  • waterYou also use water to keep your body temperature at about 37ºC.
  • Water comes out through the tiny holes in your skin called pores.
    This water we call perspiration or sweat and it helps to cool our bodies.
  • Water is in the fluids that keep your joints moving smoothly [like knees and elbows] so that your bones don't creak and groan like a rusty swing.
  • Saliva, or spit as we usually call it, is mostly water. We know when we need more water because our mouth feels dry.
  • Mucus is also mostly water. That's the stuff that you see too much of when you've got a runny nose! But mucus is very important, as it keeps eyes, ears, noses, throats and all your inside bits smooth and slippery so that everything can run around all your body systems without getting stuck!

Now that you can see how important water is, you can understand why your body needs so much of it.

Adult bodies use up around 2 litres a day and smaller bodies use less. If you are around 8 years old you might use up about 1 litre a day, so you have to replace that much water.

How to replace water

  • You will get some of that water from the foods you eat like fruit, meat vegetables, but you will still need to drink water as well.
  • Try to drink around 6 cups of water a day, more if it's hot, or you've been running around a lot, or you feel thirsty. Of course, you can drink other drinks like milk and juice - they are mostly made of water anyway.
  • Be careful with some fizzy drinks. They have water in them, but some of them have lots of sugar too [remember you don't need much sugar].
  • Some drinks, like cola drinks or coffee have caffeine in them. Look to see if caffeine is on the list of what's in your drink. Caffeine is a diuretic, which means it will make your kidneys make a lot more urine and you will have to go to the toilet and you will lose all that water again!
water If you're really into sport, you can get more information about what to drink and eat in our topic 'Food - eating and sport'.

Here are some of your questions

Which kinds of water are there and which is best?

  • Some water can have germs in it, so it is important to be sure that the water you drink is safe. If you are not sure it is safe, make sure the water is boiled before you drink it or clean your teeth with it. Water that comes from lakes or rivers sometimes has a lot of germs in it, and it needs to be treated before it is used for drinking.
  • Tap water in cities and towns in countries like Australia is safe, but water from rainwater tanks will have germs in it.
  • Chemicals like chlorine may be added to the water to kill the germs. The amount of chlorine in water will not harm you, but it may make the water smell different.
    water
  • Tap water in many countries now has fluoride added to it. Fluoride helps prevent tooth decay. The amount of fluoride added to the water supply does not cause any problems, but if you swallow a lot of toothpaste which also has fluoride in it there can be some problems (spit your toothpaste out after you've cleaned your teeth!!).
  • waterA lot of people have started to drink spring water, which has different minerals in it. The water can taste different from tap water so some people like it more. Spring water should be tested before it is sold to make sure there are no germs that could make people ill.

    Spring water is very expensive to buy in bottles, but if you are travelling to other countries where the water may not be clean, it is a good idea to use bottled water or boil the tap or well water very carefully. You don't want to get sick while you're on holiday, do you?

    Spring water does not have any fluoride in it, and since more kids have been drinking more spring water they have been getting more tooth decay.
  • Mineral water is popular as a mixer with fruit juice. If you are buying a ready-mixed drink, check out how much sugar is in there, as it may not be as healthy as it seems.

Which drinks have caffeine in them?

  • Coffee and tea both have caffeine in them and so do chocolate drinks.
  • Some soft drinks, especially cola drinks, do too, so you need to check the labels to see what's in there. As well as being a 'diuretic' (it makes your kidneys make more urine or wee) caffeine can make people feel different. Some people feel more wide-awake, while others feel shaky and anxious.
  • It is best not to have too much caffeine.

Why does salty water come out of your eyes when you cry?

  • We really don't know why people make tears when they cry, but tears are made from the water in blood. Blood has salt in it, so tears do too.

Interesting stuff about water

  • 75% of the earth is covered with water but only 3% of it can be used for drinking - (it is 'fresh' water) . Most of this fresh water is underground; the rest is in lakes and rivers.
  • People can survive for up to 4 weeks without food but cannot live without water for more than a few days.
  • Almost 2500 years ago a Greek doctor called Hippocrates (say hip-ok-rat-eez) told the people of Greece to boil water before drinking. This killed germs in it and it was safer to drink, but he did not know that there were germs in the water (this was not known until about 150 years ago). He also 'filtered' the water through a cloth to trap dirt, which helped it taste and smell better, but did not get rid of germs.
  • Water boils at 100 degrees Celsius (212Fahrenheit) and freezes at 0 degrees Celsius (32Fahrenheit).
  • Most of the fresh water we use in South Australia comes from the Murray Darling Basin, Australia's largest water catchment area. It runs all the way from Queensland down to South Australia, and covers three-quarters of New South Wales and half of Victoria. It contains more than twenty major rivers as well as important underground water systems.  Recently severe droughts (when very little rain fell) meant that the amount of water in this basin was much less than normal, so a desalination plant has been built to turn salty water from the sea into fresh water so Adelaide will always have enough water.
  • People in Australia are using less water per person than they did 10 years ago.  This is partly because there has been a drought, so there has been less water to use, and partly because people have learnt ways to save water. 

 

Are you doing your bit to save water?

 Here are some ideas.

  • You coulld take shorter showers. Giving up showers or baths in not an option!!!
  • Use water from the washing machine to water the garden ('grey' water).
  • Check that all taps are fully turned off.
  • Have a timer on the garden watering system.
  • Use a broom rather than a hose to clean paths and driveways.

Can you think of any others ways to save water?


water You don't slosh when you walk,
Or burble when you talk,
But most of you is water.

You leak it through your skin
If you're fat or if you're thin,
Stay cool, most of you is really water!


BH

Dr Kim says:

Dr Kim

Use water on the outside of your body too, to keep yourself clean and healthy.

 

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We've provided this information to help you to understand important things about staying healthy and happy. However, if you feel sick or unhappy, it is important to tell your mum or dad, a teacher or another grown-up.

 

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