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On-site sewage management systems

On-site sewage management (OSSM) systems refer to any system that treats wastewater and disposes of the effluent within the premises. If you live in a house that is not connected to reticulated sewer, you will have an OSSM system.

OSSM systems involve the treatment of wastewater followed by the release of liquid and solid products into the environment. If not maintained and treated properly, there can be serious adverse effects and impacts, including:

  • spreading of disease, bacteria, virus and pathogens
  • contamination of groundwater and surface water
  • degradation of soil and vegetation
  • spreading of unpleasant odours
  • encouraging insects and vermin.

Approval to install, alter and operate an OSSM

OSSM is regulated jointly by local councils and NSW Health and must be approved by Council before installation. You must ensure your OSSM system is maintained and working well once installed.

If you would like to install a new OSSM system on your property, or alter an existing system, you are required to gain approval from Council and submit an Application to Install/Alter and Operate an On-site Sewage Management System (refer to Section 68 of the Local Government Act 1993).

Council's On-site Sewage Management Code of Practice explains the approvals process and requirements to help you prepare your application. You can also refer to the Local Government (General) Regulation 2005, which provides you with the details of documents required to be lodged with your application:

Under the Local Government (General) Regulation 2021, Council must not approve of the installation of certain sewage management facilities unless they have been accredited by NSW Health. The types of sewage management facilities to which accreditation applies includes septic tanks, aerated wastewater treatment systems and composting toilets.

You can view a list of accredited sewage management systems on NSW Health's website.

Application and fees

You will need to pay the applicable fee at the time of lodging your application. The current fees are:

  • installation application: $351
  • modification: $95
  • unapproved existing tank: $526.

OSSM risk ratings

All OSSMs are allocated a risk rating, which determines the frequency of inspections. If you have a sewage management system that has been operating for a while, there is an opportunity to downgrade the risk rating so inspections are required less frequently.

You can apply for this if systems are well maintained and meet these criteria:

  • No defects have been identified for the past three inspections (high risk) or two inspections (medium risk).
  • The property has remained in the same ownership during the above inspections.
  • The property is owner-occupied (not tenanted or holiday rented).


More information

Contact us

If you need more information about on-site sewage management systems, please contact our Public and Environmental Health Team: