Urban water cycle

Before modern water supply systems were created, most people used buckets or urns to collect water from their village well and carry it to their homes.

Nowadays, cities like Melbourne have networks of pipes that move water from place to place:

  • water mains transport drinking water to homes and businesses
  • sewers carry dirty water to sewage treatment plants
  • stormwater drains carry rainwater running off roads into rivers, creeks and bays

This journey of water – from being collected in forested catchments to returning to the natural water cycle as purified wastewater – is called the urban water cycle. It is different from the natural water cycle because of humans, who take water for drinking, cooking and recreational purposes.

In Melbourne, the urban water cycle is managed by Melbourne Water.​

Catchments to tap

The water from your tap has travelled a long way to get there.

Most of Melbourne’s drinking water comes from mountain ash forests high up in the Yarra Ranges to the north-east of Melbourne. These catchments have been closed to most of the public for over 100 years, to make sure our drinking water stays clean at the source where it is collected.

When it rains in the catchments, some rainwater is absorbed into the ground while some runs into rivers and reservoirs. There are ten major water reservoirs that supply water to Melbourne.

Toilets to market gardens

Once homes and businesses use water, it travels through many pipes to two major sewage treatment plants in Melbourne’s east and west. These plants use a complex treatment process to remove toxic substances from the sewage.

The remaining water is then cleaned so it can be safely pumped out to sea, where it returns to the natural water cycle. Some of this purified water is recycled and used on farms, parks and golf courses.

Drains to our bays

Stormwater drains collect rainwater that runs off roads, roofs and gutters, and carry it into nearby rivers and creeks. These eventually move the water into our bays, where it re-enters the water cycle.


Urban water cycle 

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