Importance Of Water On The Earth


This is a thought about the importance of water for human being. Also briefing about uses of water, sources of water, the importance of rainwater, rain water collection, disposal of rain water etc.

Man needs air, water and food for survival. A man can live without air for not more than 3 minutes, without water for not more than 3 days and without food for not more than 3 weeks. The human body is made up of about 70% of water and 30% of solids. 

The water which we drink helps us in many ways.

Replaces loss of water from the tissues, maintains fluidity of blood and lymph, helps in excretion of waste products, acts as a vehicle for dissolving food, helps digestion of the food, regulates the body temperature

Safe and Wholesome Water has been defined as water that is,
Free from disease causing organisms
Free from harmful chemical substances
Free from colour and odour and pleasant to taste
Usable for domestic purposes

If any water sample does not fulfil the above criteria, it is said to be polluted or contaminated.

Uses of water

1) physiological use – drinking ,bathing etc
2) domestic use – cooking, washing, flushing toilets, gardening etc
3) recreational use – maintenance of gardens and public fountains, swimming pools, boating, fishing.
4) Public use – fire fighting , cleaning streets, medium of transportation
5) Industrial use – processing and cooling purposes
6) Agricultural use – irrigation for growing crops
7) Power generation – hydroelectric and thermal power
8) Waste disposal – natural medium for waste disposal

The requirement of water depends on the climate, standard of living, level of urbanization; level of industrial and economic development and habits of the people. The human needs for water are next only to that for air.

Sources of water

Rain is the primary source of water on earth. Water is present in any form on land and sea, gets evaporated by the action of sunlight. It is estimated that, every minute about 1500 litres of water is evaporated from each square kilometre of the ocean surface, in the tropical regions. The evaporated water vapour forms clouds. With changes in atmospheric conditions the vapour in the clouds condenses and this water is returned to the earth’s surface as precipitation, the term means includes rain, snow, mist, dew and hail.

Importance of Rain water 

As mentioned above, rain is the primary source of water on earth. In a few countries like Gibraltar rain water is the only source of water supply. In water scarce regions, rain water can be collected and stored for drinking purposes in underground tanks; this is called harvesting of rain water.

Rain water Collection

Rain water can be collected and stored in the following ways

1) Collection in the ground – This collection is in specially constructed areas which are made impervious (leak –proof) by cementing.
2) Collection from roofs of houses – The first portion of the rain water is to be discarded because it contains dust ,soot ( smocking black smoke ) excreta of birds etc.The latter portion of rain water is collected. Roberts rain water separator can be fixed on the rain water initially to run waste and then to collect the latter portion.

Dispose of rain water
1) Evaporation – from the heated surface of the earth. The water vapour forms the clouds
2) Transpiration – a part of the water in the soil is taken up by the plants and evaporated from the leaves.
3) Percolation – into the ground to form sub-soil or ground water. Sub-soil water can be tapped from wells of various types like shallow, deep etc
4) Surface drainage – the surface run off of rain water feeds rivers, streams, lakes, ponds and tanks. The rivers and streams ultimately flow into the sea.

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