Sewerage

Greater Melbourne's sewerage has provided Melburnians with world-class sanitation for over 100 years, protecting public health and the environment. Find out what happens when you flush the toilet or use the sink!

What is sewerage?

Our sewerage (also known as 'sewerage network' or 'sewerage system') is vital to Melbourne's health. It is a network of over 3,000 km of pipes and pumps that safely transfers sewage from homes and businesses to our treatment plans for processing, including:

  • 400 kilometres of sewers
  • 3 main trunk sewers
  • 9 pumping stations.

This map shows Greater Melbourne's sewerage and the water corporation boundaries.

Greater Melbourne sewerage map

Sewage, comprised of 98% water, is the waste water that leaves our kitchens, bathrooms, laundries and toilets, as well as from industry and businesses.

It is treated to Class A, the highest quality of recycled water, before being released into the environment. Receiving environments include Port Phillip Bay, Bass Strait and many inland waterways, such as Yarra River, Jacksons Creek and Merri Creek.

How sewerage works

Disposal

Each year, more than 320,000 million litres of sewage enters Greater Melbourne's sewerage through a network of underground pipes.

This sewage comes from homes as well as businesses. Businesses need permission to use the sewers because their trade waste is more contaminated.

Transfer

Sewage then enters one of three larger trunk sewers. These slope downwards so gravity helps the sewage flow. Eventually, pumping stations push it up to ground level to be processed at a treatment plant or to continue its journey through our sewerage, which can take up to 12 hours.

Treatment

Melbourne has two big treatment plans: the Western Treatment Plant in Werribee and the Eastern Treatment Plant in Carrum. In addition, there are lots of smaller treatment plants all around Melbourne.

The treatment plants process sewage in different ways, removing rubbish, organic matter and chemicals.

After water is treated, it can be released into the environment or disinfected to supply as recycled water.

Maintaining our sewerage

We constantly monitor and maintain our sewerage to keep it in good working condition. This involves:

  • inspecting sewers through closed circuit TV
  • cleaning sewers
  • trimming tree roots to prevent blockages, using high-pressure water jets
  • major works and projects to replace aging pipes or increase their capacity.

Sewer spills

Although we have world-class sewerage, sewage can still overflow sometimes. This happens when sewer pipes are:

  • blocked or broken by tree roots, fats or oils
  • too full after heavy rain, so very diluted sewage is released into rivers and creeks

This animation provides information on sewer spills, which can still happen despite Melbourne's world-class sewerage system.

Sewer spills video - transcript

How you can help

  • Don’t flush fats, oils or other dangerous chemicals down the sink or toilet.
  • Check your stormwater plumbing isn’t connected to sewerage.
  • Install a water tank to capture rainwater.

The past

Want to revisit the past? Find out about the history of sewerage in Melbourne, including how sewage was previously treated, and historic sewerage sites Cocoroc and Werribee Farm.

The future

To maintain Melbourne as a liveable city, we will need sewerage to do more than protect public health and the environment. We will need to manage our resources wisely, enhance liveability and support the economy - all while ensuring that sewerage remains affordable to the broader community.

For more information, read the Melbourne Sewerage Strategy: a collaboration between Melbourne Water and Melbourne's water retailers.

Last updated:
23 July 2019