Septic Tanks (on-site sewer management systems)

In non-sewered areas, the proper treatment and reuse of household wastewater on-site is critical in ensuring minimal impact to public health and the environment. Septic systems or Advanced Wastewater Treatment Systems (AWTS) have been developed as a method to achieve this.

Applications for on-site sewer systems can be made via the NSW Planning Portal

Septic Systems

A septic system consists of a septic tank combined with a disposal method such as an absorption trench (sometimes called a rubble drain), or a modified transpiration bed for heavier clay soils. A holding tank which stores the septic effluent for regular tanker truck collection and removal to a treatment facility may be required for sites where the other disposal choices will not work.

A septic tank is a structurally sound watertight tank used for the treatment of sewage and liquid wastes generally from a single household but can be designed for multiple dwellings. All wastewater from the household enters the tank. Most solids settle to the bottom forming a sludge layer, while fats and grease will collect at the top in a scum layer. Bacteria in the septic tank breakdown most of the solid matter in the sludge and scum layers. Material that cannot be broken down gradually builds up in the tank and must be pumped out periodically.

A properly sized septic tank coupled with an appropriate disposal method based on site & soil conditions along with regular maintenance and the use of septic safe products.

Advanced Wastewater Treatment Systems (AWTS)

An AWTS is a purpose-built system used for the treatment of sewage and liquid wastes from a single household or multiple dwellings.

It consists of a series of treatment chambers combined with a disposal method (usually an irrigation system). An AWTS enables people living in non-sewered areas to treat and utilise their wastewater.

Wastewater from a household is treated in several separate chambers. The first chamber is similar to a conventional septic tank. The wastewater enters the chamber where solids settle to the bottom and are retained in the chamber forming a sludge layer. Scum collects at the top and the partially treated wastewater flows into a second chamber. Here the wastewater is mixed with air to assist bacteria to further treat it. A third chamber allows additional clarification through the settling of solids, which are returned to the septic or aeration chamber for further treatment. The clarified effluent is disinfected into another chamber (usually by chlorination) and is then ready for disposal, usually irrigation.

Bacteria in the first chamber breaks down solid matter in the sludge and scum layers. Material that cannot be fully broken down gradually builds up and must be periodically pumped out the same way as for a conventional septic tank.

AWTS’s need to be serviced quarterly by an approved contractor at a cost to the owner. LPSC maintains a register of servicing each system within the LGA.