Certification for installation of wastewater treatment systems

The Department of Health (DoH) is requesting certification for all onsite wastewater treatment systems against the relevant Australian Standard as detailed in the table below.

The transitional period to obtain certification for onsite wastewater treatment systems is due on 31 December 2020.

Onsite wastewater system Volumes (L/day) Standard
Precast concrete septic tanks 6000 AS 1546.1 or *DoH approval
Glass fibre-reinforced plastic or plastic septic tanks 6000 AS 1546.1
Waterless composting toilets N/A AS 1546.2
Secondary treatment systems (Including ATUs) 5000 AS 1546.3
Greywater treatment systems/td> 1000 AS 1546.4

*DoH approval as per Appendix 1 of Code of Practice for Product Approval of Onsite Wastewater Systems (2013).

Any application to install an onsite wastewater treatment system with a capacity exceeding the volumes presented in the table above requires engineering certification.

The engineering certification needs to include the following:

1. Engineer certified drawing(s). The drawing(s) must:
    (a) provide scaled  figures of all necessary dimensions, sizes and location description and functions of all elements of the system.
    (b) have a minimum A3 size
    (c) be signed by the engineerhave a reference number or date of issue
2. Structural design certification for all tanks and chambers
3. Hydraulic loading capacity (litres/day) indicating peak and average flow rate volumes
4. System serviceable life (min 15 years)
5. The expected effluent water quality criteria based on AS 1546.3 (i.e. secondary or advance secondary with or without disinfection and with or without nutrient reduction capabilities). Please refer to table below.
6. Proof of current professional indemnity insurance coverage for the design works conducted.
7. Certification signed by a qualified Australian engineer.

Effluent quality performance criteria as per AS 1546.3

Parameter  Secondary effluent Advanced Secondary effluent
90% samples Maximum *90% samples Maximum
BOD5 ≤ 20mg/l &30mg/l ≤ 10mg/l 20
TSS ≤ 30mg/l 45mg/l ≤ 10mg/l 20
*E.Coli ≤ 10 cfu/100mL 30 cfu/100mL ≤ 10cfu/100ml 30 cfu/100mL
Turbidity N/A N/A N/A 5 NTU
**FAC Minimum 0.5 N/A Minimum 0.5 mg/L N/A
TN N/A 15mg/L 15mg/L
TP N/A 2mg/L   2mg/L

*E Coli where disinfection is required

**FAC Free available chlorine (minimum level not 90% of the samples)

Please note that future applications that do not have the engineer certification with the above requested information will be returned unapproved.

Last reviewed: 25-09-2019
Produced by

Public & Aboriginal Health Division