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Choosing an onsite wastewater system
Choosing an onsite wastewater system
Onsite disposal of wastewater is required in areas where reticulated sewerage is unavailable.
Every onsite wastewater system requires an approval before it can be installed. You can apply to install a wastewater system on your property.
Only onsite wastewater products that have been approved for use by the Department of Health can be used.
Which system to install?
In most cases conventional septic tank leach drain systems will be adequate.
Your local government may require systems that can produce treated wastewater with a high quality, such as:
Where nutrient retention is required, the local government should be consulted to determine if the system's nutrient removal capacity will meet their requirements.
There are other approved non-conventional systems that can be used to treat and dispose of wastewater onsite, such as:
- composting toilets
- incinerating toilets
- greywater systems.
Building construction sites are required to have approved temporary toilets if there is no access to toilet facilities onsite.
Understanding Primary Treatment Systems (septic tank systems)
Historically most unsewered developments in Western Australia use Primary Treatment Systems (PDF 453KB) to treat and dispose wastewater.
Last reviewed: 22-05-2026
Produced by
Environmental Health Directorate