Septic Tanks


One of the Shire's Environmental Health Services' function is to ensure that onsite wastewater treatment systems do not pose environmental or public health threats. To achieve this we attempt to ensure that all on-site effluent disposal systems are installed, operated and maintained in accordance with legislative requirements to prevent the transmission of disease and to deliver the best possible environmental outcomes, particularly with respect to our waterways.

System installations or changes to an existing system are only permitted with the approval of the Shire of Dandaragan, or for commercial premises of the Department of Health, WA. This includes both combined effluent disposal systems at premises where the sewer is not available, and also greywater re-use systems which may be installed in either sewered or unsewered areas.

The Shire of Dandaragan can only consider applications for the installation of an on-site effluent disposal system where that system has been approved for use in Western Australia by the Department of Health.

To download an Application to Construct or Install an Apparatus for the Treatment of Sewage Click here


When a developed property is connected to sewer, usually under the infill sewerage program, any on-site effluent disposal systems such as septic tank and leach drain/soak well systems will eventually require decommissioning. This entails that the contents of the tanks are pumped out by an approved contractor and the system either removed or backfilled. If the system can't be removed, the tanks should be pumped out, the bottom of the tanks broken up and the system backfilled with sand.

As there are costs involved in both, the decommissioning of the septic tanks and connecting to sewer, householders are not automatically required to decommission tanks when they connect to the sewer. Under the Health (Treatment of Sewage and Disposal of Effluent and Liquid Waste) Regulations 1974 decommissioning is required when:

  • The property is sold
  • The use of the development changes; e.g. from a residence to a child care centre
  • Building extensions that may encroach on the minimum setback requirements for the system

Septic tanks which have not been decommissioned must not be paved or built over without approval from the Shire.

The Shire requires notification to be forwarded when a system has been decommissioned. Please forward a letter to the Shire with a copy of the certification from the liquid waste contractor.