On this page
On-site wastewater management systems (commonly known as septic tank systems) are used on residential, community and business premises. They treat, then recycle or dispose of:
- greywater, which comes from showers, baths, hand basins, washing machines, laundry troughs and kitchens
- blackwater, which is toilet waste (from water-flush, incineration or dry composting systems)
- sewage, which is combined greywater and blackwater.
On-site wastewater management systems must perform effectively and be well managed to minimise risks to public health and the environment. The requirements on them depend on the source of the wastewater, site constraints, treatment method and the quality of effluent needed for the end uses of the treated water:
- Wastewater treated to primary quality is only suitable for disposal below ground via soil absorption trenches, mounds and evapo-transpiration beds or trenches.
- Wastewater treated to secondary quality can also be dispersed to land via pressure-compensating subsurface irrigation.
- Greywater treated to advanced-secondary quality can be used in the home for flushing toilets and in washing machines. It can also be used for surface and subsurface irrigation.
Permit for constructing, installing or altering an OWMS not exceeding 5000L per day
A permit from council is required to construct, install or alter an on-site wastewater management system (OWMS) with a design or actual flow rate of sewage not more than 5000L on any day.
Systems that can treat more than 5000L per day need an EPA development licence and operating licence (unless an exemption applies).
On-site wastewater management system operation and maintenance
Part 5.7 of the Environment Protection Regulations 2021 creates new ongoing obligations on a person in management or control of an OWMS. These include an obligation to operate the system correctly, maintain it in good working order, and ensure it does not overflow. There is also a new duty to keep maintenance records (and provide them to councils when requested), and a duty to notify a council as soon as practicable if the system poses a risk of harm to human health or the environment or is otherwise not in good working order.
Assessment standards for on-site wastewater treatment plants
Under the Environment Protection Act 2017 (the Act), an on-site wastewater treatment plant must meet the appropriate standard set by EPA. ‘Appropriate standard’ is defined in regulation 4 of the Environmental Protection Regulations 2021.
An on-site wastewater treatment plant type must be assessed by a body accredited under the Joint Accreditation System of Australia and New Zealand or any other accreditation body approved by the Authority (assessment body). The assessment body must certify the treatment plant as conforming with the relevant Australian and New Zealand standard (appropriate standard):
- AS/NZS 1546.1: 2008, On-site domestic wastewater treatment units, Part 1: Septic tanks
- AS/NZS 1546.2: 2008, On-site domestic wastewater treatment units, Part 2: Waterless composting toilets
- AS 1546.3:2017, On-site domestic wastewater treatment units, Part 3: Secondary treatment systems
- AS 1546.4:2016 On-site domestic wastewater treatment units, Part 4: Domestic greywater treatment systems
Transitional arrangements will also apply to previously issued certificates of conformity that had not expired by 1 July 2021.
The following table summarises the ‘appropriate standards’ and ‘transitional arrangements’ for different types of treatment plants:
|Types of on-site wastewater treatment plants||Transitional arrangements for previously issued certificates that have not expired at 1 July 2021||Appropriate standard from 1 July 2021|
|Septic tanks (and vermiculture systems)||Certificates issued against AS/NZS 1546.1 2008 will continue to be valid until they expire.||AS/NZS 1546.1: 2008, onsite domestic wastewater treatment units, Part 1: Septic tanks.|
|Waterless composting toilets||
Certificates issued against AS/NZS 1546.2 2008 will continue to be valid until they expire.
|AS/NZS 1546.2: 2008, onsite domestic wastewater treatment units, Part 2: Waterless composting toilets.|
|Secondary treatment systems||
Certificates issued against AS 1546.3:2017 will continue to be valid until they expire.
Certificates issued against AS/NZS 1546.3:2008 will continue to be valid for 2 years from commencement (that is, to 30 June 2023), or earlier if the expiry date in the certificate is earlier.
|AS 1546.3:2017, onsite domestic wastewater treatment units, Part 3: Secondary treatment systems|
|Domestic greywater systems||Certificates issued against AS 1546.4 2016 will continue to be valid until they expire.
Certificates issued against NSW Health: Domestic Greywater Treatment Systems Accreditation Guidelines February 2005 before 21 November 2016 that do not expire by 1 July 2021 will continue to be valid until the date of expiry on the certificate.
AS 1546.4:2016 onsite domestic wastewater treatment units, Part 4: Domestic greywater treatment systems.
(Note: AS 1546.4:2016 was adopted in the legislative framework on 21 November 2016).
Please note that, in highly exceptional circumstances relating to innovative on-site wastewater treatment plants, an exemption from these requirements may be granted to a permit applicant by EPA under section 459 of the Act.
EPA collates certificates of conformity and maintains a list of certificate holders against each treatment plant type.
Transitional approach for sand filter treatment plants – Section 459 exemption
Under the Environment Protection Act 2017 (the Act), councils assess permit applications to construct, install or alter an on-site wastewater management system (OWMS) with a design or actual flow rate of sewage not exceeding 5000L on any day (A20 permit). More information on this role is available in publication 1974.
Councils can only issue A20 permits where the proposed on-site wastewater treatment plant (treatment plant) has a certificate of conformity from an accreditation body confirming that it meets the appropriate standard. The Environment Protection Regulations 2021 (the Regulations) set out the appropriate standard.
For secondary treatment systems (STS), which includes sand filter treatment plant, the appropriate standard is AS 1546.3:2017: On-site domestic wastewater treatment units, Part 3: Secondary treatment systems (2017 Standard). This 2017 Standard replaced the AS/NZS 1546.3:2008 On-site domestic wastewater treatment units – Part 3: Aerated wastewater treatment systems, which applied under the Environment Protection Act 1970.
In June 2021, councils raised concerns with EPA that some plumbers and businesses who designed and installed sand filter treatment plants were unaware of the transition to the 2017 Standard and were not able to obtain a certificate of conformity as required by the Regulations in time for commencement of the Act.
Class exemption instrument
On 13 December 2021, EPA granted a class exemption instrument under section 459 of the Act (Sand Filter Class Exemption).
The Sand Filter Class Exemption allows applicants to a council for a permit to construct or install an OWMS that includes a sand filter treatment plant to be exempt from the requirement to provide a certificate of conformity for the sand filter treatment plant. The exemption only applies if the conditions of the Sand Filter Class Exemption have been satisfied.
This exemption only relates to the provision of a certificate of conformity. Other obligations under the Act and Regulations continue to apply.
Councils continue to have obligations under the Act when assessing permits – importantly, they must refuse to issue a permit if they consider the activity in the application poses an unacceptable risk of harm to human health or the environment.
More information about the Regulations can be found here.
The Sand Filter Class Exemption will replace the current temporary approach of s.459 individual exemption forms and will expire on 30 June 2023.
How the Sand Filter Class Exemption will be used
When a person applies to a local council for an A20 OWMS permit that includes a sand filter treatment plant, the application must include either a certificate of conformity for the proposed treatment plant or a copy of the Sand Filter Class Exemption. If the applicant is relying on the Sand Filter Class Exemption, they must also provide detailed plans and specifications which demonstrate the proposed treatment plant satisfies the conditions in the class exemption.
The class exemption instrument has been granted and a summary of the conditions that must be satisfied is listed below.
Sand filter treatment plant must:
- only treat effluent that has been subject to either primary, or primary and secondary treatment; and
- be appropriate for its proposed use on the proposed site; and
- have a base and sides made of impermeable material that cannot be punctured by any media layer or equipment; and
- operate effectively during normal, intermittent, and peak hydraulic flow and organic load conditions; and
- be capable of continued utilisation during breakdown, power failure or maintenance periods for at least 24 hours without posing a risk of harm to human health or the environment; and
- have an alarm system with suitable visual or audio (with mute facility) indicators to warn of any failure of the system; and
- have inspection and access openings for all chambers brought up to ground level; and
- comply with the relevant dosage rate specifications set out in the class exemption instrument.
If a local council assessing an A20 permit application for an OWMS that includes a sand filter treatment plant concludes that the conditions in the class exemption have not been satisfied, then the council must advise the person that their application does not comply with the Act. The council may also require an applicant to provide more information relating to the application.
Guidance on on-site wastewater management
- Code of practice – Onsite wastewater management (publication 891)
- Guidance for owners and occupiers of land with an OWMS ≤ 5000 litres on any day (including septic tank systems) (publication 1976)
- Victorian land capability assessment framework (Word 1.1MB; Municipal Association of Victoria)
- EPA has worked with the City of Casey through the OPLE program to develop a video on maintaining septic systems under 5000L. For further information about your septic system, contact your local council.
Reviewed 16 December 2021