Onsite Wastewater Disposal
The majority of properties in the Shire of Kojonup are not connected to reticulated sewerage and rely on onsite wastewater systems to treat and dispose of household sewage. Managing these systems correctly is essential to protect public health, our waterways and the environment we all share. To find out if your property has sewer available conduct a search of the Water Corporation’s property rating system here.
What is an Onsite Wastewater System?
An onsite wastewater system (OWS) is a system that collects, treats and disposes of — or reuses — domestic wastewater within an individual allotment. This includes septic tanks, aerated treatment units, composting toilets, leach drains, soak wells, greywater systems and temporary systems.
Greywater refers to domestic wastewater from baths, showers, basins, laundries and kitchen sinks, specifically excluding water from toilets. Blackwater refers to wastewater containing products of human excretion.
You Must Have Approval Before You Install
It is an offence to commence construction or installation of any wastewater system without prior approval.
It is also an offence to commission a system prior to final inspection and approval to use from the local government.
All applications must be lodged with the Local Government Authority (LGA) in the first instance. If the proposed system will handle less than 540 litres per day of wastewater and the building to be serviced is a single dwelling, the LGA will process your application. If the wastewater volume generated is more than 540 litres per day and the building is not a single dwelling, the LGA will assess the application and forward it to the Department of Health for processing.
Only Approved Systems Can Be Used
Only approved wastewater systems can be used in Western Australia. Premises owners who install an unapproved system contravene the Health (Treatment of Sewage and Disposal of Effluent and Liquid Waste) Regulations 1974.
Maintaining Your System
Onsite wastewater systems require regular maintenance to function correctly and protect both your family's health and the local environment. If septic tanks accumulate too much sludge and scum, the volume of the tank is reduced, which means not all solids, grease and oils will separate — these will then pass into leach drains or soak wells and clog the surrounding soil.
As a guide, tanks should be pumped out every eight years for a two-person household, every four years for a four-person household, and more frequently for larger households.
To keep your system working well:
- Do not flush non-biodegradable materials, old medicines or large amounts of disinfectant or chemicals
- Minimise fats and grease entering the system
- Use low-phosphate, low-chlorine detergents where possible
- Have your system inspected and serviced regularly by a licensed contractor
Decommissioning an Existing System
When a developed property is connected to sewer, any onsite effluent disposal systems such as septic tanks and leach drains will eventually require decommissioning. This means the contents of the tank are pumped out by an approved contractor and the system is either removed or backfilled.
How to Apply
To apply for approval to install or alter an onsite wastewater system in the Shire of Kojonup, contact the Shire's Environmental Health Officer on 08 9831 2400 or email council@kojonup.wa.gov.au. Your application will need to include:
- Details of the proposed system (type, brand, size)
- A site plan showing the location of the system, setbacks from boundaries, buildings and any bores or waterways
- A soil assessment report confirming site suitability
Application to Construct or install an Apparatus for the Treatment of Sewage
It is always best to speak with your licensed plumber about your preferred system so that they may offer you some practical advice regarding installation and maintenance.
Plumbing Diagrams
Plumbing diagrams are maintained by the Department of Mines, Industry Regulation and Safety. A search for plumbing diagrams can be conducted online here.
For further information on approved systems and regulations, visit the WA Department of Health at www.health.wa.gov.au.
Fees:
Domestic Applications:
- Local Government Application Fee - $118.00
- Fee for the grant of a permit to use an apparatus - $118.00
Commercial Applications:
- Local Government Report Fee - $170.50
- WA Health Dept Application Fee - $102.00 (Payable to Health dept)
- Fee for the grant of a permit to use an apparatus - $118.00