Onsite wastewater systems provide a method of on-site wastewater disposal that can be used to allow development of land where deep sewerage is not available.
Septic tanks
Many suburbs, including parts of Mullaloo, Burns Beach, Sorrento, Marmion, and Duncraig, initially used septic tanks. While most of these areas have transitioned to deep sewerage, some septic tanks might still exist underground. Deep sewerage remains unavailable for certain lots that are larger than 2,000sqm in Kingsley (between Lake Goollelal and Wanneroo Road), and a small section of Joondalup, necessitating the use of septic tanks or alternative onsite treatment and effluent disposal methods such as Aerobic Treatment Units (ATUs).
Requirements include:
- Regulations generally prohibit constructing buildings or structures within 1.2m of septic tanks or ATUs or 1.8m from effluent soak wells and leach drains, unless otherwise approved.
- Areas above septic tank systems should not be paved unless access to the system is still available without requiring the removal of paving. Consequently, properties with septic systems face limitations on constructing pools, retaining walls, gazebos, or granny flats. However, when deep sewerage becomes accessible, property owners can connect to the sewer and decommission their septic tanks and wastewater systems.
Greywater systems
Greywater is used to describe the wastewater generated from bathrooms, laundries and kitchens, but does not include toilet wastewater. The opportunity exists for greywater to be re-used to irrigate gardens and, considering the dry environment in many parts of Western Australia, it is important that water is used efficiently and conserved whenever possible. Only approved greywater systems can legally be installed in WA.
For more information visit the Department of Health website.
Guidelines for installation and decommissioning of wastewater systems
An application must be lodged to construct and install an apparatus for on-site wastewater disposal. The installation of a septic tank apparatus must comply with the Health (Treatment of Sewage and Disposal of Effluent and Liquid Waste) Regulations 1974.
Application requirements
Complete an Application to Construct or Install an Apparatus for the Treatment of Sewage (PDF).
Instructions for completing the application form:
- Complete Sections 1-8 in full.
- Ensure plans and drawings are according to the specifications detailed in Section 7 of the application form.
- Ensure relevant application fees detailed in Appendix 2 are paid.
Application process
- All applications must be lodged to the City in the first instance.
- Only approved wastewater systems can legally be installed in WA.
- The City will process your application if the proposed apparatus will treat less than 540 L/day of wastewater OR the building to be serviced is a single dwelling.
- If the wastewater volume received by the system is more than 540L/day and the building being serviced is not a single dwelling the City will assess your application and prepare a local government report.
- The report and application will then be forwarded to the Department of Health for processing.
How to apply
All applications must be lodged to the City in the first instance.
Lodge an application:
- In person - Visit the City of Joondalup Administration Centre at 90 Boas Avenue, Joondalup.
- By post - Post your application to the City at PO Box 21, Joondalup WA 6919.
Decommissioning a septic apparatus involves having the tank pumped out and either removing or backfilling the system.
Decommissioning process
In order to decommission a septic apparatus the following steps must take place:
- The septic apparatus is first to be pumped out by a licensed liquid-waste contractor
- The contractor will then provide a receipt
- The apparatus can then be removed. All septic tanks, soak wells and leach drains in the system must be found and removed. The most effective way to ensure that the entire system is removed is to follow the pipe work from each septic tank and/or soak well until it ends, ensuring that there is no outlet to another soak well or leach drain. Soak wells and leach drains may be connected in series and in parallel
- The holes left behind must then be backfilled with clean sand. It is also important that the sand be compacted to prevent any possible voids.
Where it is not practicable to completely remove the septic apparatus, then an alternative option is to backfill the entire system (septic tanks, soak wells, leach drains) where it remains in the ground.
Backfilling involves filling the system with clean sand that is then compacted to prevent any possible voids.
Please note that, in the case of backfilling, the base of the septic tanks must first be completely broken to allow for proper drainage. It is recommended that, wherever possible, the septic system be completely removed, particularly where there may be an intention to further develop a property.
Timeframe for decommissioning
As septic systems can collapse without warning, the City recommends that any septic system should be decommissioned as soon as possible once connection to the sewerage system has been made. Legally, however, decommissioning is not an automatic requirement once sewerage connection is made.
Decommissioning becomes a legal requirement in the following instances:
- Within 60 days of a change of use or ownership of the premises once reticulated sewerage has been connected to the property
- In advance of building works that will result in a structure being closer than 1.2m from the septic system.
Notifying the City of a septic system decommissioning
Property owners should advise the City once a septic apparatus has been decommissioned, by completing a decommissioning form, indicating the number of septic tanks and soak wells or leach drains that were removed, together with a copy of the liquid waste receipt as evidence of the pumping out of the system (where relevant).
How to notify the City
Useful resources
For more information on waste water systems visit the Department of Health website.
The WA Department of Health Code of Practice for the Reuse of Greywater (PDF) outlines acceptable greywater re-use practices to ensure the conservation of ground and surface supplies and the protection of health standards. The installation and operation of all greywater systems must comply with the code.