Domestic wastewater treatment systems (septic tanks)

In areas where reticulated sewer is not available, sewage (toilet and kitchen water) and sullage (from baths, laundry, showers etc.) must be treated and contained within the boundaries of the property. This is done through the use of domestic wastewater treatment systems, commonly known as septic systems. These treat solids, greases and fats through natural bacteria living in the tank, and discharge wastewater into designated leaching areas. There are approximately 6,000 of these systems in use in Nillumbik.

When managed and maintained correctly, these systems are a safe and effective method of discharging of wastewater. However, if systems fail and release untreated wastewater into local waterways or stormwater drains, they can be a threat to public health and the environment.

Domestic wastewater can contain a number of pollutants such as particles of dirt, lint, food, and human waste products and chemicals derived from detergents and other cleaning products. These can lead to possible health risks or damage to the environment:

Health risks 

 • spread diseases such as bacteria and viruses,   • gastroenteritis, giardia, cryptosporidiosis, hepatitis    • high nutrients toxic to native plants    

• attract vermin and insects   • promote weed growth    

• odour   • damage soil structure    

   • reduced water quality impacting on stream fauna and vegetation    

 Environmental risks    
alter acidity/alkalinity balances in soil    

Although property owners are responsible for maintaining the system on their property, Council is responsible for ensuring septic tanks do not cause a nuisance or public health risk according to the Public Health and Wellbeing Act 2008. For this reason, and to better manage domestic wastewater issues in the Shire, Council developed the Nillumbik Domestic Wastewater Management Plan 2003-06. For more information regarding septic tanks and their management, click on the links below for more information on the relevant topics.