Skip to main content


Community Healthy Health Services Public Health

On-site Wastewater Systems

The safe disposal of sewage and household wastewater is necessary to safeguard the health of the community and protect the environment. Where connection to a reticulated sewerage system is not practicable, installation of a waste control system incorporating a septic tank is an acceptable alternative.

What is a septic tank?

The septic tank is an underground watertight tank generally constructed of concrete or plastic which is usually divided into at least two compartments. The tank receives all sewage and separates the solid portion of the waste from the liquid portion. The liquid portion (effluent) is then treated and passes out of the tank after approximately 24 hours. There are several methods of disposing of this effluent. Some use absorption trenches, others use aerobic wastewater treatment systems, aerobic sand filters, composting toilets and reed beds.

Existing septic tanks

If you have a septic system, it should be regularly cleaned of accumulated solid waste every 4 years. You will need to keep an eye on the volume of water that flows into the system and it is important to remember that chemicals can cause the system to malfunction. It is also important to regularly check around the tank to regularly check for and report any damp patches where the absorption trenches are located.

For more information on septic tank maintenance and use, download this Adobe PDF copy of the Septic tank maintenance fact sheet Septic tank maintenance fact sheet from SA Health.

Aerobic wastewater systems

Aerobic (meaning with air) systems break down solids initially, but then brings wastewater in direct contact with air so that air-breathing bacteria can improve the quality of the liquid.

Aerobic wastewater treatment units or treatment plants are underground concrete chambers where effluent from the septic tank is agitated to introduce more oxygen and then filtered.

Aerobic wastewater treatment units must be serviced by the system manufacturer or an accredited service agent at 3 monthly intervals or as recommended by the manufacturer in the service manual.

All aerobic systems must be provided with an alarm system to alert occupants to an electrical or mechanical malfunction.

For more information on aerobic systems, download this Adobe PDF copy of the Aerobic wastewater system maintenance fact sheet Aerobic wastewater system maintenance fact sheet from the South Australia Department of Health.

New septic tanks

Not all sites have characteristics suitable for conventional subsurface effluent disposal; therefore, it is very important to carry out the necessary investigations to determine the suitability of the site and design the system accordingly.

Approval must be obtained from City of Salisbury before proceeding with the installation of a septic tank system.

For information and forms, visit the On-site Wastewater information page for business or contact the City of Salisbury Public and Environmental Health Division (PEH).

City of Salisbury PEH contact details

City of Salisbury
Public and Environmental Health Services

12 James Street, Salisbury SA 5108