1.The sun’s heat evaporates seawater and turns it into a gas called water vapour.

2.The light water vapour rises, cools and condenses into tiny droplets which make up cloud.

3.Further cooling and condensation results in precipitation.

4.Surface run-off(rivers) and soakage returns most of the water to the sea ( some water is evaporated immediately back into atmosphere

And the whole cycle beings again

Importance of Water

  • The plants that provide us with food need water to grow. Farm animals need water and plants in order to survive
  • We each need an average of litres of water a day just for drinking and cooking
  • It is estimated that ¾ of all diseases in the 3rd world are related to a lack of clean water and sanitation.
  • In the Sahel region of Africa drought and desertification are resulting in terrible suffering.
  • A person can survive only a few days without water
  • A toilet flush uses up to 10 litres of water
  • Farmers in dry regions often use irrigation to increase yields from their land.


Polluting our Water Supplies

  • The overuse of fertilisers sometimes results in too many nitrates and phosphates entering rivers and lakes.
  • This causes the rapid growth of weed-like algae. The algae can use up so much of the water’s oxygen supply that fish and other water creatures die
  • Untreated household sewage can pollute water and harm human health. In 2007 up to 210 Galway people became ill when human sewage polluted their water supply
  • Chemical or industrial waste can pollute water and poison fish life. People who eat fish that have been affected by pollution can also be poisoned.