Water

RDA

Water is absolutely essential to life. Over 70% of the human body is made up of water. It is found in

Muscles

Saliva

Blood

Digestive juices

Mucus

Sweat

Composition of Water

Water contains the elements hydrogen and oxygen. They are present in the ratio 2:1, two parts hydrogen to one part oxygen. Pure water freezes at 0C and boils at 100C.

Sources of Water

The main sources of water are drinking water and beverages like tea, coffee and alcoholic drinks. Water is also present in many other foods like meat and fish. Fruits and green vegetables are high in water. Almost all foods contain water, except those with a high fat content (butter or lard), and dry foods (sugar and flour).
	Beverages
	Solid foods

Functions of Water

It is the chief component of all body fluids.

It helps dissolve foods and aids digestion.

It helps remove waste material from the body.

It regulates body temperature by perspiration.

It is a source of dissolved minerals such as flourine and calcium.

It keeps the body fluids liquid so that they may flow easily.

RDA of Water

As 2-2.5 litres of water are lost daily by excretion, and perspiration, an equal amount is required daily by the body to avoid dehydration. 1.5 litres of water is obtained from beverages and 0.8 from food.

ACTIVITIES
1. Make a list of the types of spring water available in your area.
2. Record the cost per litre.
3. If a teenager weighs 70kg how many kgs of the body weight is water?
4. Record the water content of your 5 favourite foods.
5. Why do you need to drink plenty of liquid with a high fibre diet?
6. Why do foods with a high water content decay more quickly than dry foods?

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