On-site wastewater systems, such as septic tanks and aerated wastewater treatment systems (AWTS), and their land application systems, for example sprinklers and below ground drippers, can be easily damaged during a bushfire.

Avoid driving or walking near a fire-affected system until it is assessed by a licensed plumber or service technician familiar with on-site wastewater systems. 

Contact with effluent or untreated wastewater from damaged on-site wastewater systems can cause illness and should be avoided at all times.

Last updated: 11 May 2021

Bushfire damage

On-site wastewater systems may be damaged by bushfire. These systems should be inspected by a licenced plumber or authorised service technician familiar with on-site systems to determine the extent of the damage. Concrete tanks are less susceptible to damage but should still be inspected.

If your system is damaged and presents an immediate safety risk, action should be taken as soon as practicable to make it safe. For example, if the lid is missing, place a temporary cover or fencing around the system to prevent access to the area.

The system may need to be pumped out prior to an inspection, however it is advisable to only leave the tank empty for a short time.

Wastewater systems

Plastic and fibreglass on-site wastewater systems, or systems made with plastic components, are more susceptible to damage than concrete tanks particularly if installed above ground. This includes shallow PVC pipes, plastic tanks and sumps, and plastic irrigation pipework which may be installed above or below ground. Pumps and other equipment with electrical components may also be damaged.

It is recommended that damaged on-site wastewater systems are not used until repaired or replaced.


Due to the risks associated with using systems after a bushfire, the following actions are recommended:

  • If the on-site systems are damaged, make arrangements to repair the system as soon as possible to prevent sewage from backing up into the house.
  • Avoid driving or walking near underground pipes, tanks and tank covers and their land application systems, which may have been weakened or damaged.
  • Reduce water use as much as possible until the system is inspected and repaired by:
    • Reducing the frequency of toilet flushing for liquid waste
    • Taking shorter showers or shower elsewhere
    • Limiting laundry and dishwashing as much as possible. If possible avoid using automatic clothes washers and dishwashers.
  • If the power has not been restored, the septic tank can be used as a temporary holding tank and pumped out periodically, provided the tank is not damaged. You may need to disconnect the pump (if present) and block the outlet to the land application area. If the tank is significantly damaged and can’t be used as a temporary holding tank, do not use the system until it is repaired or replaced.
  • Once power is restored, ponding may occur near the wastewater system and these areas should be avoided. Contact a licenced plumber or authorised service technician to reassess the system.
  • Replace shallow PVC pipes if they have melted as they may cause blockages.
  • Repair or replace damaged electrical components and pumps as soon as possible.

Further advice

The manufacturers of on-site wastewater systems should have information and user manuals about their systems on their web sites.

Sanitation is very important for the whole community. Your local Council is able to provide further advice about measures that can be taken while on-site wastewater systems are repaired or replaced.

For further information

Current as at: Tuesday 11 May 2021
Contact page owner: Environmental Health