1. Water The role of water in the diet
Water is not a nutrient but is required for life.
Your body is about 70% water.
Every cell and tissue in your body contains water.

2. How water is lost from your body
Hydration
Your body can survive for only a few days without water.
Hydration is the supply of water to maintain the correct amount of fluids in your body.
Each time you breathe, sweat or urinate you lose water.
To stay healthy, it is important to replace the water you lose
How water is lost from your body
Lungs: When you breathe out, water is lost as vapour.
Skin: When you sweat, water evaporates to cool you down.
Kidneys: When you go to the toilet, water is lost in your body waste.

3. The functions of water 1. Cooling the body
Body temperature is 37°C. If the temperature increases by just a few degrees, then body cells will be damaged. To prevent this, the body sweats. The evaporation of this water allows the body to cool down.
You sweat more:
In hot conditions
When you are exercising
When you are ill and your temperature rises
Therefore in hot conditions, when exercising and during illness you should drink more water.

4. 2. Removing waste from the body
Water is needed to transport waste products from the body.
It prevents constipation and allows waste products to move through the intestines.
The kidneys filter the blood and produce urine.
3. Helping the body to use the food you eat
Water is an important part of saliva, it helps you to swallow food.
In the stomach, food mixes with acid and water to help digestion.
Nutrients are released from the food and transported around the body by the blood stream.
Your blood is about 90% water.

5. How much water is needed each day?
The amount of water you need depends on many factors, such as:
Your age
Your size
How active you are
The climate (weather)
Most people need about 1.5–2 litres of water each day – this is about 8 average sized glasses.
What counts as water?
Water is the best drink as it does not contain sugar, additives or artificial sweeteners and it is a neutral pH.
Other fluids can come from low sugar soft drinks, milk and fruit juices as well as tea, coffee and other drinks made with hot and cold water.
About 20–30% of the water you need comes from the food you eat. Some foods, such as soup, cucumber, melon and oranges, are high in water.
70 – 80% from drinks and drinking water

6. Which water is best?
Drinking tap water is the most economical way to consume water and having a reusable water bottle which is washed and re-filled each day is good practice.
Bottled water – very popular, in 2014 on average in UK = 40 litres per person
Bottled water must come from an identifiable source and may be still or sparkling and makes a good alternative to sugary soft drinks.
Spring water must originate from an underground source, be bottled at source and be safe without treatment
Flavoured water is a soft drink which can contain minerals, vitamins, flavouring and sweeteners

7. Too much water can be harmful
A lack of water
When your body does not have enough water you become dehydrated.
Signs of dehydration:
Feeling thirsty
Dark urine
Headaches
Lack of energy
Feeling lightheaded
Too much water can be harmful
Drinking too much water is uncommon. However, consuming excessive amounts of water in a short space of time, such as drinking 4 litres of water in less than 2 hours, can be dangerous and can even cause death. This is because the water dilutes the sodium in your blood too much. This is called water intoxication.
More information on water intoxication can be found at:
In the search box type: ‘Can you drink too much water?’