Types of Sewage Treatment Systems

If your property isn’t connected to a council sewer network, you’ll need an effective on-site sewage treatment system to safely manage your household wastewater. There are several different types of sewage treatment systems out there on the market, from traditional underground septic tanks to advanced and modern aerated wastewater treatment systems (AWTS) and home sewage treatment plants (HSTPs).

Each wastewater treatment system works differently and is specifically designed to suit your property type, household size, soil conditions and environmental needs. Choosing the correct sewage treatment system can improve your overall household safety, reduce environmental impact and ensure your property is compliant with your local council regulations.

In this guide, we’ll explain the most common types of sewage treatment systems used throughout the Sunshine Coast and Brisbane, including how they work, their benefits and the types of properties they are installed in.

What is An On-Site Sewage Facility (OSSF)?

An On-Site Sewage Facility (OSSF) is an incredibly broad term used to describe any wastewater treatment system that disposes and treats raw sewage on a property. OSSF systems are most commonly installed in rural and semi-rural properties where there is no access to a council sewer network.

An OSSF collects all "blackwater" (toilets) and "greywater" (showers, sinks, laundry), processes it through various stages, and safely returns the treated effluent to the environment via one of two methods:

• Primary Treatment: Relies on gravity and natural settling (e.g., traditional septic tanks venting into absorption trenches).
• Secondary Treatment: Actively purifies wastewater using mechanical aeration, filtration, and disinfection (e.g., HSTPs and AWTS), producing water clean enough for surface or subsurface garden irrigation.

Aerated Wastewater Treatment Systems (AWTS)

Aerated Wastewater Treatment Systems, also known as AWTS, are among the most popular sewage treatment systems in Brisbane and the Sunshine Coast.

Unlike traditional septic tanks, AWTS systems actively treat your home’s wastewater using oxygen and naturally occurring bacteria. This treatment process produces higher-quality effluent suitable for environmentally sensitive areas and for use in subsurface irrigation systems. They also reduce the risk of your groundwater being contaminated.

Home Sewage Treatment Plants (HSTP)

A Home Sewage Treatment Plant (HSTP) is an advanced wastewater treatment system that is designed to process raw household sewage into a high-quality and safe effluent.

Home sewage treatment plants use a series of treatment stages to separate the solids from the liquid, organic matter and flush away any harmful bacteria. Many modern HSTPs use aeration technology, filtration and sophisticated disinfection processes to improve the overall treatment performance.

HSTPs are perfect for and provide a sustainable and long-term wastewater management solution for:

• Acreage properties
• Rural homes
• New residential developments and buildings
• Homes in environmentally sensitive areas or bushland

Septic Tank Systems

This is arguably the oldest wastewater management system in the world, yet they are still a mainstay in many homes throughout Queensland. Raw sewage enters an underground concrete or poly tank where solids sink to form sludge, and oils rise to form scum. Natural anaerobic bacteria slowly break down the organic matter. The remaining clarified liquid effluent overflows out of the septic tank and flows into underground absorption trenches or leach drains, where the soil performs the final filtration. 

Their simple and “set-and-forget” design makes them a great option for busy families and homes who are looking for a low-maintenance sewage treatment system.

Which Sewage Treatment System Is Best For Your Property?

Choosing the right type of sewage treatment system for your home depends on several factors:

Property Size

If your home is on a smaller block, you might benefit from a compact AWTS system or a traditional septic tank. Larger properties need more flexibility.

Soil Conditions

Before installing a septic system, check what soil is most common on your property. For example, Brisbane has a lot of clay, which absorbs water poorly.

Household Size

The number of bedrooms and how many people live in your home is the key to figuring out how much your septic system can handle.

Environmental Considerations

Homes and properties near protected ecological zones, dams or areas with high water tables face strict environmental protections.

Council Requirements

Always check your local council laws and regulations to see what sewage systems can be approved and installed on your property.