Wastewater management

Managing wastewater on your property

If you live in or rent a house that is not connected to the main sewer, then chances are that your yard contains an on-site sewage management system. If this is the case then you have a special responsibility to ensure that it is working as well as it can.

Some of the most popular types of on-site sewage management systems and provide some general information to help you maintain your system effectively. You should find out what type of system you have and how it works.

It is important to keep in mind that maintenance needs to be performed properly and regularly. Poorly maintained on-site sewage management systems can significantly affect you and your family's health as well as the local environment.

What is an on-site sewage management system?

A domestic on-site sewage management system is made up of various components which - if properly designed, installed and maintained - allow the treatment and utilisation of wastewater from a house, completely within the boundary of the property.

Wastewater may be blackwater (toilet waste), or greywater (water from showers, sinks, kitchens and washing machines), or a combination of both. Greywater (sullage) can have a high percentage of the same pollutants as blackwater.

Partial on-site systems - e.g. pump out and common effluent systems (CES) - also exist.

Other systems or methods used includes chemical toilets, septic closets, composting toilets, cesspits and pans.

How does an on-site sewage management system work?

For complete on-site systems there are two main processes:

  • treatment of wastewater to a certain standard
  • its application to a dedicated area of land.

The type of application permitted depends on the quality of treatment, although you should try to avoid contact with all treated and untreated wastewater, and thoroughly wash affected areas if contact does occur.

Treatment and application can be carried out using various methods:

Septic tank

Septic tanks treat both greywater and blackwater, but they provide only limited treatment through the settling of solids and the flotation of fats and greases. Bacteria in the tank break down the solids over a period of time. Wastewater that has been treated in a septic tank can only be applied to land through a covered soil absorption system, as the effluent is still too contaminated for above ground or near surface irrigation.

Aerated wastewater treatment systems

Aerated wastewater treatment systems (AWTS) treat all household wastewater and have several treatment compartments. The first is like a septic tank, but in the second compartment air is mixed with the wastewater to assist bacteria to break down solids. A third compartment allows settling of more solids and a final chlorination contact chamber allows disinfection. Some AWTS are constructed with all the compartments inside a single tank. The effluent produced may be surface or sub-surface irrigated in a dedicated area.

Composting toilets

Composting toilets collect and treat toilet waste only. Water from the shower, sinks and the washing machine needs to be treated separately (for example in a septic tank or AWTS as above). The compost produced by a composting toilet has special requirements but is usually buried on-site.

These are just some of the treatment and application methods available, and there are many other types such as sand filter beds, wetlands, and amended earth mounds. Council or the NSW Department of Health have more information on these systems if you need it.

What are land application areas?

These are areas that allow treated domestic wastewater to be managed entirely on-site.

The area must be able to utilise the wastewater and treat any organic matter and wastes it may contain. The wastewater is rich in nutrients, and can provide excellent nourishment for flower gardens, certain shrubs and trees. The vegetation should be suitably tolerant of high water and nutrient loads.

Location of the application

Treated wastewater has the potential to have negative impacts on public health and the environment. For this reason the application area must be located in accordance with the results of a site evaluation, and approved landscaping must be completed prior to occupation of the building. Sandy soil and clayey soils may present special problems.

The system must allow even distribution of treated wastewater over the land application area.

Warning signs

Regular visual checking of the system will ensure that problems are located and fixed early.

The visual signs of system failure include:

  • surface ponding and run-off of treated wastewater
  • soil quality deterioration
  • poor vegetation growth
  • unusual odours

Regulations and recommendations

The NSW Department of Health determines the design and structural requirements for treatment systems for single households. Councils are responsible for approving the installation of smaller domestic septic tank systems, composting toilets and AWTSs in their area, and are also responsible for approving land application areas. The NSW Environment Protection Authority approves larger systems.

The design and installation of on-site sewage management systems, including plumbing and drainage, should only be carried out by suitably qualified people. Care is needed to ensure correct sizing of the treatment system and application area and an approval to install and then operate is required.

Heavy fines may be imposed under the Clean Waters Act if wastewater is not managed properly.

Keeping your on-site sewage management system operating well

What you put down your drains and toilets has a lot to do with how well your system performs. Maintenance of your sewage management system also needs to be done well and on time. The following is a guide to the types of things you should and should not do with your system.


  • Learn how your sewage management system works and its operational and maintenance requirements.
  • Learn the location and layout of your sewage management system.
  • Have your AWTS (if installed) inspected and serviced four times per year by an approved contractor. Other systems should be inspected at least once every year. Assessment should be applicable to the system design.
  • Keep a record of desludgings, inspections, and other maintenance.
  • Have your septic tank or AWTS desludged every three years to prevent sludge build up, which may 'clog' the pipes.
  • Conserve water. Conservative water use around the house will reduce the amount of wastewater which is produced and needs to be treated.
  • Discuss with Council the adequacy of your existing sewage management system if you are considering house extensions for increased occupancy.


  • Don't let children or pets play on land application areas.
  • Don't water fruit, vegetables and lawn with effluent.
  • Don't extract untreated groundwater for cooking and drinking.
  • Don't put large quantities of bleaches, disinfectants, whiteners, nappy soakers and spot removers into your system via the sink, washing machine or toilet.
  • Don't allow any foreign materials such as nappies, sanitary napkins, condoms and other hygiene products to enter the system.
  • Don't put fats and oils down the drain and keep food waste out of your system.
  • Don't install or use a garbage grinder or spa bath if your system is not designed for it.

Reducing water usage will lessen the likelihood of problems such as overloading with your septic system. Overloading may result in wastewater backing up into your house, contamination of your yard with improperly treated effluent, and effluent from your system contaminating groundwater or a nearby waterway.

Your sewage management system is also unable to cope with large volumes of water such as several showers or loads of washing over a short period of time. You should try to avoid these 'shock loads' by ensuring water use is spread more evenly throughout the day and week.

Help protect your health and the environment

Poorly maintained sewage management systems are a serious source of water pollution and may present health risks, cause odours and attract vermin and insects.

By looking after your management system you can do your part in helping to protect the environment and the health of you and your community.

For more information please contact the Sustainable Environment Department, Kempsey Shire Council, Civic Centre West Kempsey. Telephone 02 6566 3240

Further information