Natural water cycle

The natural water cycle is the continuous movement of water around the world through the processes of precipitation, infiltration and run-off, evaporation, transpiration and condensation.

Natural water cycle process

water cycle

Water is continually moving through the natural water cycle.

What happens in the natural water cycle?

  • Precipitation is when water falls from the sky as rain, hail or snow.
  • Infiltration is when water falls on the ground and soaks into the earth.
  • Run-off is the water that doesn't soak into the ground, but flows into creeks, rivers and oceans.
  • Evaporation is when water turns into a gas called water vapour and rises into the air.
  • Transpiration is when water is released into the air, as water vapour, by plants.
  • Condensation is when water vapour turns back into a liquid in the sky and the cycle starts again.

Water is continually moving through the natural water cycle.

Earth has exactly the same amount of water as it had thousands of years ago. This cycle is also called the hydrological cycle.

We modify and manage part of the natural water cycle to provide humans with water. This is called the urban water cycle.
 

  • The total amount of water on earth is 1,386 million km3
  • Water covers about three quarters of the earth’s surface.
  • 97.5 % of the world’s water is saltwater. 
  • 2.5% is of the world’s water is freshwater, but most of it is frozen or not easy to get.
  • Less than one per cent of the world’s fresh water is useable.

Water on Earth graph

Less than 1% of the water on earth is useable for drinking.

Water is the most common substance found on earth. It's the only substance found naturally in three forms – solid (as ice), liquid (as water) and gas (as water vapour).

Water is made up of tiny molecules. One water molecule, called H2O, is made up of three atoms - two hydrogen atoms and an oxygen atom. These atoms stick together due to electrical energy.

Water is a solvent, which means it dissolves things. Wherever it travels, water carries chemicals, minerals and nutrients with it. This means water is more than what we can see.

There is a fixed amount of water on earth and it's constantly moving from one place to another in a process called the water cycle.