Sewage, comprised of 99% 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.
What happens after you flush
Ready to find out what happens after you flush? There are three key steps: disposal, transfer and treatment:
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.
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.
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
The Western Treatment Plant (WTP) 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.
Eastern Treatment Plant
The Eastern Treatment Plant (ETP) 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.
Prefer video to digest this information? Watch this video for an overview:
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:
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.
Biosolids are the solid organic material left over after sewage treatment. These treated biosolids look and smell like soil, and contain beneficial nutrients like nitrogen, carbon and phosphorus.
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.