Teacher background information
A hundred million years ago, when dinosaurs were roaming the earth, the planet had the same amount of water that is has today. Water is constantly being recycled as it evaporates, condenses and trickles back to earth as precipitation. This is called the water cycle.
Available fresh water is a limited resource
- 72% of the earth’s surface is covered by water.
- 97% is salt water in the oceans.
- 2% is frozen water in icecaps and glaciers.
- 1% of the earth’s water is potential freshwater supply.
Demand for water
As populations grow, water demand also grows. As the quality of life continues to improve for people around the globe our water demands increase with large amounts of water needed to raise cattle, harvest grain, and produce clothing, electronics, and energy.
Since 1950 global water use has nearly tripled. Competition for water takes place between people, types of users and ecosystems.
Australians are among the highest users of water per capita in the world, and Perth remains one of the highest water using cities in Australia.
Western Australians have done a great job of reducing our water use over recent years and the community has become more aware of the need to conserve water. It is important that this trend continues to improve given our drying climate.
Residential households are the highest users of public water, using around 71% of water supplied from the Integrated Water Supply System. This means that households have the greatest potential to save water.
In Western Australia total consumptive water use in 2014–15 was 3476 gigalitres. The sectors that used this water were:
- mining: 37% (1274 gigalitres)
- public water scheme supply: 17% (602 gigalitres)
- agriculture: 16% (556 gigalitres)
- irrigation scheme supply: 14% (474 gigalitres)
- commercial and institutional: 9% (325 gigalitres)
- industry and power generation: 3% (111 gigalitres)
- other: 1% (52 gigalitres).
Source: Department of Water Annual report 2015.
With less than 1% of earth’s water available for drinking, sanitation and freshwater species it is imperative that we learn to share this critical resource. Learning how much water we use and then learning how to conserve water may be the best way to help ease the competition.