What is an Onsite Wastewater Management System?

    As their name suggests, Onsite Wastewater Management Systems are a way of managing wastewater on properties that do not have a connection to the sewer network.  

    Often called ‘Septic Tanks’, there are many different types of systems that take wastewater and toilet waste generated by a household or business, treat it through biological and chemical processes, and then dispose of it by dispersing it via an absorption field - usually under the ground - within the property boundaries.

    Every time you have a shower, do the dishes, or flush the toilet, the wastewater generated is transferred to the system where it goes through tanks, chambers, lines, and trenches on the way to becoming less damaging to people and the environment.

    Is the term 'Onsite Wastewater Management System' the same as 'Septic Tank'?

    Although often commonly referred to as ‘Septic Tanks’, it is important to note that septic tanks are only one type of onsite wastewater management system.

    There are a number of different types of ‘Onsite Wastewater Management Systems’ approved for use by the Environment Protection Authority including:

    • Septic Tanks
    • Waterless Composting Toilets
    • Secondary Wastewater Treatment Systems
    • Aerated Wastewater Treatment Systems
    • Domestic Greywater treatment systems

    What are the risks associated with Onsite Wastewater Management Systems?

    Untreated (or inadequately treated) wastewater has long been recognised as posing a serious threat to public health.  Wastewater may contain disease causing pathogens (viruses, bacteria, and parasites), chemicals, and other contaminants from household, industrial or commercial activities.

    Many of these substances can cause disease when ingested by humans so prevention of contamination of food and water supplies with sewage or blackwater is critical to preventing disease of both individuals and entire communities.  This is especially important in our water catchments areas, where leaking or failing systems can potentially contaminate the water we use for drinking.

    The discharge of untreated or poorly treated wastewater into either surface or ground water also has the potential to seriously impact our environment, with impacts on both plant and animal species.  The delicate ecological balance can be damaged due to increased levels of nitrogen and phosphorus, and exposure to chemicals and pathogens.

    Who regulates Onsite Wastewater Management Systems?

    Local Councils are responsible for overseeing all systems that are designed to treat daily flows of less than 5000L.  Systems larger than this are managed by the Environment Protection Authority directly.

    What is the 'General Environmental Duty' and how does it apply to me?

    The general environmental duty (sometimes shortened to ‘GED’) is at the center of the new Environment Protection Act 2017 and it applies to all Victorians

    The General Environmental Duty requires every Victorian to reduce the risk of their activities harming the environment or human health.  You can read more about what this means for the Victorian Community by visiting the Environment Protection Authority website.

    If you are the owner or occupier of a property that relies on an Onsite Wastewater Management System (Septic Tank) you have legal responsibilities under the General Environmental Duty to ensure that the system is working properly and that it does not pose a risk to others.

    This includes:

    • Making sure that the system does not leak or overflow
    • Maintaining the system, ensuring that it is checked regularly and de-sludged, or serviced as required
    • Having the system fixed quickly by a licensed contractor if it is not working properly 
    • Maintaining and protecting the absorption field and lines and ensuring that all treated wastewater remains within the boundaries of your property
    • Complying with Local Council requirements in relation to installation, alterations, maintenance, and use.
    • If you are the landowner, providing written information about how to use the system to any tenants 



    Where can I learn more about Onsite Wastewater Management?

    The Environment Protection Authority (EPA) has worked with the City of Casey to develop an easy-to-follow video that explains how these systems work, and all of the things that you can do to ensure that your system continues to work at its best.