Septic tanks and effluent waste disposal

​​​​​​The majority of areas within the City of Kwinana are connected to the sewer network, however the rural and industrial areas often require on-site effluent disposal systems to be installed.​

Conventional primary treatmet septic systems are no longer approved in the City of Kwinana. Only certain approved wastewater systems can be installed within the City of Kwinana environmentally sensitive areas including within the Public Drinking Water Source, Peel Harvey Catchment or Cockburn Sound Catchment areas.

Application to Install an Effluent Disposal System

All onsite effluent disposal systems installed within the City of Kwinana must be assessed and approved by the City’s Environmental Health team.

The installer should complete the Application to Construct or Install an Apparatus for the Treatment of Sewage​​ and submit with the prescribed fee, plans and specifications as per the form. The fee is made up of two charges, these being a fee for an 'Approval to Construct an Apparatus' and a fee for a 'Permit to Use' an apparatus once it is installed and a final inspection is conducted.

Applications for premises that produce more than 540L of sewage per day, other than single dwellings servicing up to 8 persons, must be approved by the Department of Health. Additional fees apply in these cases as a Local Government Report will need to be prepared. ​​

Please note that it is illegal to use an onsite effluent disposal system unless it has been approved for use by an Authorised Officer and a 'Permit to Use' has been issued.

Selecting an Effluent Disposal System

For a list of approved nutrient retentive effluent disposal systems (Advanced  Secondary Treatment Systems, Aerated Wastewater Treatment Systems or Alternative Treatment Systems, please visit the Department of Health’s website.​

Unless sewer is available on the property, the following areas are required to be connected to nutrient retentive effluent disposal system to ensure that phosphorous or nitrogen does not impact on natural water bodies. 

  • Wellard (West of Freeway), Kwinana Beach, Naval Base, Hope Valley, Postans, the Spectacles and Mandogalup – total nitrogen (TN)
  • Wellard (East of Freeway), Wandi, Casuarina, Anketell – total phosphorus (TP)

To check if your property is connected to sewer or has availability to sewer, contact the Water Corporation on 13 13 95 or visit their website.

Mechanical equipment wash down

Washing down is not permitted unless the area is connected to sewer or an approval for an on-site waste water disposal system has been granted by the City of Kwinana or Department of Health. Please note the Water Corporation’s requirements for vehicle and machinery wash-down areas. You must apply to the City of Kwinana to install an apparatus for the disposal of treated liquid waste discharge where reticulated sewer is not available. Where reticulated sewer is available you must apply to the Water Corporation for an Industrial Waste Discharge Permit.

Guidance on requirements and discharged wastewater quality for washdown facilities can be found on Department of Water and  Environmental Regulations Water Quality Protection Note 68.

Legislation

There are a number of relevant legislations, policies and guidelines that govern the installation, operation and maintenance of effluent disposal systems:

Decommissioning of septic tanks

When a property is connected to mains sewer, the property owner is required to decommission the existing septic tank and effluent disposal system when the following circumstances arise;

  • there is a change of ownership of the property. Accordingly, the new owner has 60 days to decommission the septic tank apparatus;
  • there is a material change in the use of the premises. Accordingly, the owner has 60 days to decommission the septic tank apparatus; or
  • if the foundations for a building on the premises are to be built closer than 1.2m to the septic tank apparatus or a building is to be constructed above the septic tank apparatus or closer than 1.8m to any leach drain or soakwell. Accordingly, the owner shall decommission the septic tank apparatus before the building work commences

Decommissioning means that;

  • all septic tanks, soakwells and/or leach drains are pumped empty by a licensed Liquid Waste Contractor; and
  • all empty septic tanks, soakwells and/or leach drains must be either removed or have their lids and bases broken and filled with clean sand.

Please read the Decommissioning Guidelines​ for further information.​​

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