Water is the most common substance found on earth, so why is it important? Water is essential for all forms of life and can dissolve nearly anything. It can exist as a gas (water vapour and steam), a liquid (water) and a solid (ice).
It is these unique chemical properties of water make it crucial for all life on earth.
Water covers 75% of the earth’s surface, however only a very small amount is fresh water that can be used directly by people, animals and plants because:
- 97% of this water is in oceans and is too salty for people, animals or plants to use
- 2% is frozen at the north and south poles, in glaciers and on snowy mountain ranges.
Water is made of tiny molecules, each so small that you can’t even see them with the most powerful microscope. These molecules are made up of three atoms: two hydrogen atoms and one oxygen atom. These atoms stick together due to electrical energy and, together, they are called H2O.
- Water is the only substance on Earth that naturally occurs as a solid, a liquid, and a gas.
- These changes of state require heat exchange which is important to the redistribution of heat energy in the atmosphere
- Water has a high specific heat, and so it can absorb large amounts of heat energy before it begins to get hot and releases energy slowly when situations cause it to cool.
- This helps moderate the Earth’s climate and helps organisms regulate their body temperature
- Water in a pure state has a neutral pH, so is neither acidic nor basic
- changes in pH occur when substances are dissolved
- rain is naturally acidic, with a pH of about 5.6, because it dissolved carbon dioxide and sulphur dioxide.
- Water conducts heat more easily than any liquid except mercury.
- This causes large bodies of water to have a uniform vertical temperature
- Water is a universal solvent and is able to dissolve a large number of different chemical compounds.
- This feature also enables water to carry solvent nutrients in runoff, infiltration, groundwater flow and living organisms
- Water has a high surface tension and tends to form drops
- this allows water and dissolved nutrients to move through plants and blood via tiny vessels in the bodies of some animals
Water is essential for all life and is the most abundant substance on Earth, yet water scarcity is one of the biggest issues facing us today. Australia is the world’s driest inhabited continent and has the lowest rainfall and the lowest water runoff. Most water is Australia is used in Agriculture reducing environmental flows.
You can be part of the solution by looking at your water usage and exploring way that you can be more Waterwise.
The natural water cycle has been modified by people to ensure a constant water supply and the safe disposal of wastewater. The Urban Water Cycle incorporates the Water Supply System, Wastewater system and the Stormwater system.