What happens after you flush?

Sewage, comprised of 98% water, is the wastewater that leaves our kitchens, bathrooms, laundries and toilets, as well as from industry and businesses. Find out what happens after you flush, then read the benefits of 'poo power' harnessed by the treatment process.

Where your sewage goes

Ready to find out what happens after you flush? There are three key steps: disposal, transfer and treatment:

First, disposal

Melbourne Main Sewage Replacement Project (MMSR), Flinders Wharf, Wurundjerri Way bypass
Site progress works, from Melbourne Main Sewerage Replacement Project (MMSR).

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.

Then, 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.

Finally, treatment

Melbourne has two big treatment plants: the Western Treatment Plant in Werribee and the Eastern Treatment Plant in Carrum. There are lots of smaller treatment plants all around Melbourne too.

Did you know these treatment plants process sewage in different ways, removing rubbish, organic matter and chemicals?

Western Treatment Plant

Aerial view of sewage treatment lagoons at the Western Treatment Plant

The Western Treatment Plant is a place of historic and cultural significance. It sustainably treats half of Melbourne’s sewage, and is a thriving ecosystem with an internationally recognised bird habitat.

Learn more about the sewage treatment process at the Western Treatment Plant, which produces 40 billion litres of recycled water.

Western Treatment Plant

 

Eastern Treatment Plant, birdlife in the lagoon

Eastern Treatment Plant

The Eastern Treatment Plant is one-tenth the size of the Western Treatment Plant, but treats nearly half of Melbourne’s sewage: 330 million litres a day. Find out how it uses innovative processes to turn sewage into Class A recycled water.

Eastern Treatment Plant

 

Prefer video to digest this information? Watch this video for an overview:

 

 

Raindrop character moving through bacteria

Hot tip: Discover more with our fun, interactive game, Drip Trip. Get ready to steer Drippy around obstacles as you bust a move (or fatberg) through your neighbourhood's pipes, sewers, drains and waterways.

 

 

Benefits of sewage treatment

See how we're reaping the benefits of the sewage treatment process through the production of recycled water and energy:

Recycled water

Melbourne Water sign saying 'Recycled Water in Use'

Before sewage is released into the environment or disinfected to supply as recycled water, it is treated to Class A, the highest quality of recycled water.

Discover more how Melbourne Water produces recycled water, following strict regulatory guidelines – and how it is a key initiative in securing our water supply.

Recycled water

 

Generating energy 

Staff at Eastern Treatment Plant

Sewage is much more than a waste product. We can generate electricity by combusting biogas, which is captured under covers that are placed over our sewage treatment lagoons.

Discover how biogas is used to power both the Western and Eastern treatment plants, how we're reusing 'biosolids', and how we're working toward net zero carbon emissions.

Energy

 

 

Last updated:
9 May 2020