On-site sewerage facilities (OSSF) treat sewerage on properties in unsewered areas.
Effluent must always be disposed of within your property boundary. It is illegal to discharge effluent into neighbouring properties, gutters, waterways, or any area where it could run off into waterways.
Odour from a neighbouring on-site sewer system can be reported by contacting us.
Do
- Schedule regular maintenance with an approved service agent (required by law).
- Use biodegradable, septic-safe products.
- Avoid direct contact with effluent or irrigation sprays.
- Call your service agent if you notice alarms, odours or unusual system behaviour.
- Conserve water and fix leaks promptly.
- Use toilet paper that breaks down easily.
- Keep detailed records of your system: model, service agent, maintenance history and parts replaced.
- Learn how your system should look, sound and smell when operating correctly.
- Ensure tank lids are sealed to keep out mosquitoes and vermin.
- Keep sprinklers in their approved locations to prevent runoff or spraying onto neighbouring properties.
Don’t
- Put food scraps, milk or oil down the sink.
- Dispose of chemicals, paints, thinners, pesticides or harsh cleaners—they kill essential bacteria.
- Allow vehicles, play equipment or heavy items on the land application area.
- Let roof or surface water enter the system; it will overload it.
- Flush foreign objects like wipes, sanitary products, plastics or coffee grounds.
- Switch off the system to save power.
- Cover tanks with earth, mulch or materials that block maintenance access.
- Park or drive over any part of the system.
- Make repairs or alterations without our approval.
- Use garbage grinders unless your system is designed for them.
In Crows Nest and parts of Cambooya township, households use a CED system where each household has a septic tank, but instead of disposing of treated effluent on-site, the system connects to our sewer network for final treatment. The solids remain on the property in septic tanks which are pumped out as required by private contractors. The pumping out of the tank is the owner's responsibility.
An OSSF is a self-contained system that treats and disposes of wastewater entirely on your property, making it ideal for homes and businesses in rural or remote locations where town sewerage isn’t available.
The types of on-site sewerage facilities (OSSF) that may be installed are:
- Aerated wastewater treatment system (AWTS): Typically know as an on-site treatment plant (OSTP), these systems are the most common. Wastewater is treated in tanks with multiple chambers with the use of mechanical, biological and filtration methods. Treated wastewater is dispersed to an approved area of land.
- Aerobic sand filter system: This system works like the aerated wastewater sewage treatment plant but uses a primary tank for natural treatment which then undergoes secondary treatment by passing through a carefully graded and layered bed (filter) of sand and/or gravel to pass oxygen to micro-organisms to treat and purify the wastewater. The treated effluent is then discharged to an approved area of land.
- Advanced Enviro-Septic system (AES): This is a passive, non-mechanical wastewater treatment facility. An AES system uses natural tiny organisms to make the water cleaner. After primary treatment occurs in the septic tank, wastewater enters the AES system where it travels through vents and sand for more cleaning. After this, the treated water soaks into the soil in the approved area.
- Septic tank: A septic tank is a relatively simple design making use of natural processes to treat wastewater. A septic tank will separate solid and liquid waste, forming three levels of waste; scum (oils & grease), wastewater, and sludge (particles that are heavier than water), disposing of wastewater into the approved drainage beds/trenches.
- Composting dry vault system: Composting toilets break down human waste using air, tiny living organisms, and small insects. This process turns the waste into a soil‑like material.
- Holding tank: A holding tank is a collection tank that holds untreated effluent when it cannot be treated and disposed of in a land application area on a property. These tanks are required to be pumped out by a licenced liquid waste contractor and disposed at a sewerage treatment facility.
How to install or alter an on-site sewerage facility
- You will need to consult with a qualified site and soil evaluator, hydraulic designer, engineer or your plumber to discuss your options for effluent disposal.
- You must obtain a plumbing application approval before installation or alteration works. This will involve submitting a:
- site and soil evaluation report
- on-site sewerage facility design
- drainage design.
3. On-site sewerage facilities must comply with and are assessed under:
- Plumbing and Drainage Act 2018
- Queensland Plumbing and Wastewater Code 2025
- Standards Australia AS/NZS 1546 and AS/NZS 1547
- our policies and guidelines.
On-site sewerage facility maintenance
On-site sewerage facilities require regular maintenance to ensure they operate safely and effectively. They must be functioning properly to not adversely affect public health, safety or the environment. We monitor the maintenance of OSSF across the region to ensure the required maintenance is completed.
Poorly treated and maintained on-site treatment facilities can release contaminates such as waterborne pathogenic microorganisms into the environment, potentially causing harm to the health of humans and the environment. Impacts of poorly treated effluent include:
- soil contamination
- contamination of bodies of water and groundwater
- public health risks
- damage to ecosystems and organisms.
Treatment requirements
Septic systems
If a septic tank accumulates too much sludge and scum, the effective volume of the tank is reduced, which reduces the amount of separation that can take place. This means not all the solids, oils and grease will separate, causing solids to pass out of the septic tank and into the drainage beds/trenches. This can clog the soil surrounding the drainage beds/trenches.
Common tasks to maintain your septic system include:
- cleaning the outlet filter every three months
- desludging the septic tank every three to five years by a licenced liquid waste contractor
- mowing grass and maintaining the land application area.
Aerated wastewater treatment plants and sand filter systems
Periodic servicing must be completed by a licenced service agent. It is the responsibility of the property owner to engage an agent and maintain a contract for servicing while the system is in use.
Service requirements are commonly:
- aerated wastewater treatment plant - every three months
- sand filter system - every 12 months.
Composting dry vault systems
Periodic cleaning is advised for composting dry vault systems. To keep the compost pile and toilet healthy and clean:
- add bulking agent regularly (carbon-based material)
- don’t add foreign objects e.g. food scraps
- don’t use harsh chemical cleaners or soaps
- clean the pedestal, seat and lid regularly.
If compost begins to produce nasty odours, the system is not working correctly and will need to be addressed.
A list of the approved treatment systems is available from the Queensland Government website.
Larger onsite systems with over 20 equivalent persons require ERA 63 approval and further monitoring from the Department of Environment, Science and Innovation.
On-site treatment facilities must be decommissioned properly to prevent future risks to public health and the environment. A plumbing approval is required before any work begins.
Steps for decommissioning
- Request a plumbing approval for the work.
- Pump out the tank. All effluent and sludge must be removed by an approved liquid waste contractor. Keep the receipt for our verification.
- Neutralise contaminants. Treat the empty tank with ag-lime or hydrated lime.
- Ensure drainage. Puncture one or more holes in the bottom of the tank for proper drainage.
- Break down the structure. Remove concrete lids and break tank walls below ground level.
- Fill and compact. Fill the tank with crusher dust and compact to surface level. If settling occurs, top up as needed.