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What is the water cycle? | City of Melbourne Urban Water

What is the water cycle?

The water cycle is the movement of water around the earth.

As a result of natural processes, water transfers between the land, rivers, creeks, ocean and atmosphere in a continuous cycle.

The amount of water on earth stays fairly constant over time, but it is naturally cleaned and replenished though the water cycle. It takes about 10,000 years for a drop of water to complete the cycle.

As water moves through the cycle it changes state, from liquid in the waterways and oceans, to gas in clouds, and to solid in the form of snow and ice.

The water cycle is an essential ecosystem that supports all life on earth.

The value of stormwater

Although excess amounts of stormwater can cause problems in urban areas, it is a very valuable resource for enhancing the liveability of our city.

In Melbourne, the volume of stormwater runoff from our rainfall is greater than the amount we actually use from our dams. This volume of water is more than enough to provide both an alternative supply for non-drinking purposes and a healthy flow to our waterways and bays. Natural treatment processes can remove pollution from stormwater so it can be used for non-drinking purposes, such as watering gardens.

We have built several systems in the municipality to capture and treat stormwater, and we are always looking for more opportunities.

We need to value and use Melbourne’s rainfall to minimise water price increases, reduce urban flooding, to improve the health of waterways and bays and enhance liveability, self-sufficiency and amenity.

Find out more

How does urbanisation impact the water cycle?
Learn how the natural water cycle is impacted by buildings and sealed roads.

The natural water cycle


Move your mouse over the picture to learn more about the natural water cycle.

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with the State Government of Victoria
This website was delivered in partnership with the State Government of Victoria