Water is a scarce and limited resource. There are many uses, such as:

Uses of Water

• Agriculture: to water plants
• Industrial:
  • Heated to make steam to turn turbines
  • Cooling down reactors
• Domestic:
  • Household e.g. cooking, cleaning, drinking
  • Recreational, e.g. swimming, sports
• Environmental: preserving water in a dam

Evolution of Global Water Use

MEDCS - MORE INDUSTRY AND DOMESTIC, VERY LESS AGRICULTURE

LEDCS - MORE AGRICULTURE, LESS DOMESTIC, LEAST INDUSTRY

Methods of Water Supply

• Dams: barrier placed across a river made from concrete
• Reservoirs: the artificial lake that develops behind a dam
• Wells: a shaft sunk into the ground to obtain water
• Desalination:
  • Thermal: evaporation of water to remove salt
  • Reverse Osmosis: forces water through semi-permeable membrane to remove salt
• Sewage Treatment:
  • Removal of contaminants from wastewater & household sewage
  • Requires physical, chemical & biological processes to remove all the contaminants and make safe

Causes of Water Shortages

• Population Growth: increased pressure on water sources as world's population grows
• Pollution: water sources are being polluted by industries