Find out when you need approval, how to apply and what your responsibilities are when it comes to installing or maintaining a septic tank or wastewater system.
Is your property serviced by the SA Water sewer network?
SA Water sewer networks don’t service all locations in the City of Mitcham. You’ll find unsewered areas in:
- Bedford Park
- Belair
- Bellevue Heights
- Blackwood
- Brownhill Creek
- Crafers West
- Coromandel Valley
- Eden Hills
- Hawthorndene
- Leawood Gardens
- Mitcham
- Upper Sturt
If you live in an unsewered area, you need an on-site system to dispose/treat your wastewater.
Not sure if you’re serviced by the SA Water sewer network? Visit SA Water and enter your address.
There are two main types of on-site wastewater systems
Septic tank systems collect waste from the house via an inlet pipe at one end of the tank.
The tank is divided into two chambers, and as the waste enters the first chamber, the solids settle to the bottom and the scum floats to the top. The solids are anaerobically digested by bacteria to make them smaller.
The liquid waste then moves through to the second chamber where more settlement happens, and then excess liquid moves out of the outlet pipe to the soakage area. The soakage area needs an engineer's report to assess soil conditions and the area required for soakage. This also depends on the amount of waste produced by the property.
If there’s waste in the septic tank that doesn’t decompose, it’ll eventually build up and need to be removed by a licensed contractor. We recommend desludging septic tanks at least every four years.
If your septic tank system is properly designed, it shouldn’t smell, unless it’s during the occasional pump out. The waste can’t be used on gardens and must be disposed of in the underground soakage area because septic tanks are a primary treatment system.
Aerobic systems are like septic tanks, but they use aerobic processes for decomposing the waste instead of anaerobic process. Unlike primary-treated septic tank waste, aerobic wastewater systems treat the waste to a secondary level, so you can reuse wastewater on gardens and lawns as irrigation.
Similar to a septic tank, aerobic systems work by waste entering the first chamber and large solids settling out. The second chamber has an aeration stage, where aerobic bacteria digests the biological wastes in the wastewater.
After it leaves the second chamber, it goes through a disinfecting stage where (usually) chlorine tablets mix with the water for a secondary treatment. The wastewater then gets sent to either an underground soakage area or an above ground irrigation system.
Aerobic Systems need quarterly services by qualified technicians, who’ll need to submit service reports to your local authority.
There are many types of systems and a licensed plumber or wastewater engineer can help you choose the one that's right for you. Some of them are listed below:
Before you install a wastewater system, it’s important to know:
You’ll need to apply to our Environmental Health Team if you want to install new on-site systems or alter your system.
Both septic tanks and aerated wastewater treatment tanks need to be pumped every four years by a licensed contractor to remove the solids.
For further information on wastewater systems, visit the SA Health Website.
Wastewater FAQs
If you still need some help, get in touch with our Environmental Health Team on 1300 133 466.
All of your wastewater applications are assessed under the South Australian Public Health Act 2011, South Australian Public Health (Wastewater) Regulations 2013 and On-site Wastewater Systems Code.
You may need a wastewater engineer’s assessment report for your site (including aerobic wastewater treatment systems installations). Your report should show the type of system, site and soil details, and the size of disposal/recycled water area it needs.
You can download the Wastewater System Application Form here to submit a wastewater system application.
The fees include:
- An application fee to install or alter a system that does not exceed 10 equivalent people $125
- An application fee to install or alter a system that exceeds 10 equivalent people $125.00 and an additional $27.00 for every two people beyond that initial 10.
- An inspection fee where we are the relevant authority of $139
- As each site has it’s own requirements, it is best to get the advice of a specialist wastewater plumbing company.
- You may just need to provide us with site plans and underfloor plumbing layout plans, however you may need to obtain a detailed wastewater engineer’s report following an assessment of your site.
Your underfloor plumbing plans need to show:
- How you want to use the building and rooms inside it
- How you’ll connect the building’s internal sanitary plumbing fixtures to the external sanitary drainage system, including the:
- Location of the sewer drain
- Size and grade of sewer drain
- Location of inspection openings
- Location of inspection shafts
- Junctions and bends
- Position of overflow relief gully and how you’ll maintain the water seal
- Size of waste pipes
- Size of vents
- Show whether fixtures are trapped or untrapped
- Any non-standard fixtures
You’ll need to maintain your system for it to keep working well.
If you have a question that we haven’t covered, give the Environmental Health Team a call on 1300 133 466