On-site Sewerage Facilities

A large number of properties across the region are not connected to a reticulated sewerage system. The treatment, storing and disposal of all wastewater generated on these properties must be undertaken by an on-site sewerage facility.

The types of on-site sewerage facilities that may be installed are:

  • Aerated Wastewater Sewage Treatment Plant
  • Aerobic Sand Filter System
  • Advanced Enviro-Septic
  • Septic Tank
  • Holding Tank
  • Composting Dry Vault System

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 or safety or the environment.

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 and Heritage Protection

On-site sewerage facilities (OSSF) treat sewage generated on a property in an area not serviced by sewerage infrastructure. A facility may use mechanical, biological and/or filtration methods to treat, store and dispose treated waste through either above- or below-ground irrigation systems within a property boundary. OSSF include all types of wastewater treatment and land application such as aerated wastewater sewage treatment plants, sand filter systems, septic tanks, holding tanks and composting dry vault systems.

These systems aim to treat wastewater to:

  • Protect public health and safety
  • Maintain and enhance environmental quality
  • Maintain and enhance community amenity

Aerated Wastewater Treatment System

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 a designated and approved land application area (LAA).

Aerobic Sand Filter Treatment 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 land application area.

Advanced Enviro-Septic

Advanced Enviro-Septic (AES) is a passive, non-mechanical wastewater treatment facility. An AES system utilises natural micro-biological process to purify the wastewater to a higher standard effluent. After primary treatment occurs in the septic tank, wastewater enters the AES system circulating through low and high vents surrounded by sand. After treatment, effluent infiltrates into underlying soil within the approved land application 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.

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.

Composting Dry Vault System

Composting toilets use a process of biological degradation to convert nightsoil into a humus-like substance through the aerobic action of micro-organisms and invertebrates.


Maintenance is required on sewerage facilities but differs depending on the type of system you have. State legislation requires aerobic wastewater sewerage treatment plants to be serviced every three months and sand filter treatment systems annually. Servicing must be completed by a licenced service agent, engaged by the property owner. Service agents are required to carry out maintenance and advise Council on the performance of system.

The effective volume in a septic tank is reduced if the tank accumulates too much sludge and scum, which reduces the amount of separation that can take place. This means not all solids, grease and oils will separate and will pass out of the septic tank into the trenches/beds, potentially clogging the surrounding soil of the trenches/beds. Important maintenance considerations for septic tanks include desludging the septic tank every three to five years by a licenced liquid waste contractor, using septic safe products and maintaining the land application area.

Common complaints that arise can be from overflowing trenches, unpleasant odours, and wastewater flowing into neighbouring properties. These issues and more pose serious health risks to the community and the environment and need attending to immediately. System failures and faults are often caused by one or a combination of the following:

  • Lack of system maintenance
  • Poor or failed mechanical components
  • Harsh household cleaning chemicals, killing essential bacteria
  • Excessive use, shock to the system
  • Blockages
  • Saturated/overflowing LAA
  • Incorrect facility design or installation
  • Odours from OSSF

We're upgrading to a new simplified system for onsite treatment plant monitoring and compliance. WasteID is the application selected by TRC to facilitate this. This system will be rolled out across the Region in 2024.

What is WasteID?

WasteID provides a new interactive QR code tag. The secure WasteID tag simplifies the requirements for registering and servicing each onsite treatment plant. The cloud-based WasteID register is integrated with Council’s own data bases and IT systems.

How does WasteID work?

An authorised service agent uses their smart device to scan the WasteID tag. The device and other details are automatically loaded, so the applicable test results can be entered. The tester’s GPS location is checked against that of the device and a Form 11 is automatically generated.

Key benefits:

  • Simplified system
  • Real-time data
  • Interactive platform
  • Automatic scheduling of servicing
  • Electronic test results (Form 11) to service agent, property owner and Council immediately

Greywater is the wastewater generated from baths, showers, washbasins and laundries.

Find out more (TRC website).

Common Effluent Disposal (CED) is in place in Crows Nest and parts of the Cambooya township. Each household will have a common septic tank but instead of disposing of treated effluent through trenches on the property, it is connected to the reticulated sewerage system. This conveys the sewage to either a centralised wastewater treatment plant or to a lagoon sewage treatment facility.

It is the responsibility of the property owner to ensure the maintenance of their CED tank.

You will require Council approval to install or alter an on-site sewerage facility or greywater facility.

One of the important aspects when installing an OSSF is the requirement for a thorough site and soil evaluation to be undertaken as part of the process of obtaining approval for effluent disposal within the property. It is essential for the evaluator to select the most suitable on-site effluent disposal facility for the property and engage the best environmental practices to support property design. The quality of effluent from an on-site sewerage facility is a key consideration to determine how sewage effluent is to be controlled and disposed of within the property.

Before lodging an application to install an on-site sewerage facility, it is recommended that the property owner consults with a site and soil evaluator to discuss the options available for effluent disposal within the property.

The following documents are required for an unsewered plumbing application to Council.

  • Site and soil evaluation
  • Onsite sewerage facility design
  • Drainage design (applicable for a new structure)

To read more, please visit Submit a plumbing and drainage application

Onsite Treatment Facilities must be decommissioned correctly to ensure the facility does not pose a future risk to the public or health of the environment.

A plumbing permit is required prior to any work associated with decommissioning an onsite treatment facility. To read more, please visit Submit a plumbing and drainage application

On-site sewerage facilities must comply with and are assessed under:

  • The Plumbing and Drainage Act 2018
  • The Queensland Plumbing and Wastewater Code 2019
  • Standards Australia AS/NZS 1546 and AS/NZS 1547
  • Council Policies and Guidelines