What is sewage?
Sewage originates in our homes and industries. Domestic sewage consists of everything that goes down the plughole in the kitchen, bathroom, toilet and laundry. It also includes the 'gully' trap, but should not include run-off from roofs, streets, driveways, etc. which flow into the stormwater or drainage system. On average, three quarters of the water supplied to domestic customers and most of the water supplied to industrial customers ends up being collected by the sewerage system. Naturally, this proportion varies from summer to winter and depends on whether you live in a flat or a house with a large garden.
We own and operate a network of sewer pipes and pump stations to collect sewage from customers. Around 93% of the sewage collected is transferred to Melbourne Water for treatment at either the Western or Eastern Treatment Plants		Find out about the composition of sewage.
Rain water which falls on urban areas and any excess water from garden watering or other outdoor uses is directed to the stormwater drainage system, which generally drains to a local creek, river or ocean. The stormwater collection system is separate to the sewage collection system and is operated by local government and Melbourne Water. Illegal connections of stormwater to the sewerage system is a cause of sewers overflowing. Additionally, water used in industry for purposes such as cleaning is collected by the sewerage system. Water collected from industrial and commercial properties which goes to the sewerage system is known as 'trade waste'.
Treated water from the Western Treatment Plant (formerly known as Werribee Farm) is released into Port Phillip Bay, where it rejoins the natural water cycle. Treated water from the Eastern Treatment Plant rejoins the natural water cycle in Bass Strait.		Find out if 'greywater' can be used for your garden.
Around 7% of the sewage we collect is treated in small treatment plants we own and operate. These plants principally service outer areas which are too distant for sewage to be economically transferred to the Melbourne Water system. Because the water from these treatment plants is released into rivers and streams, a high standard of treatment is provided.
There are also some parts of our licence area where there is no sewerage system. Properties in these areas usually have septic tanks. A program is underway to provide sewerage services to properties which are too small for septic tanks to work effectively.