When investing in a wastewater treatment system—whether for a rural home, new development, eco-tourism park, or commercial facility—you’re bound to encounter a sea of jargon. Terms like “AWTS,” “HSTP,” “Advanced STS,” and “MBR” are thrown around in quotes and council approval documents, often with little explanation.
If you’re not a wastewater engineer, it’s easy to feel overwhelmed. But understanding the core differences between these systems is essential to choosing the right solution—one that meets your environmental needs, budget, property size, soil conditions, and regulatory requirements.
In this guide, we break down the key jargon and compare common wastewater treatment systems in Australia, including:
OSSM vs HSTP
AWTS vs Septic Systems
Advanced STS vs Basic Systems
Advanced STS vs AWTS
AWWS vs MBR
Let’s demystify these terms so you can confidently choose the system that suits your project.
What is a Wastewater Treatment System (WWTS)?
At its simplest, a wastewater treatment system manages and treats the water that leaves your toilets, sinks, showers, laundry, and kitchen—collectively called “blackwater” and “greywater.” Without proper treatment, this wastewater can contaminate soil, waterways, and groundwater.
In urban areas, treatment is typically handled by central sewerage systems. But in rural, regional, or off-grid locations, an on-site wastewater system is required. These include septic tanks, AWTS (Aerated Wastewater Treatment Systems), HSTP (Household Sewage Treatment Plants), and more advanced or modular systems.
Jargon Breakdown: Common Wastewater System Types
Let’s look at each system type and what the jargon really means.
1. OSSM (On-Site Sewage Management)
OSSM is an umbrella term used in NSW and other states to describe any on-site method of sewage management. It includes systems like:
Septic tanks with absorption trenches
AWTS units
Sand filter systems
Composting toilets
Greywater treatment systems
Jargon Tip: OSSM isn’t a specific system—it’s a category. Councils use this term when referring to the overall management of sewage on a property. You’ll need to submit an OSSM application or plan to your local council for approval before installation.
2. HSTP (Household Sewage Treatment Plant)
An HSTP is a mechanical system that treats all domestic wastewater to a higher standard than a basic septic tank. In many contexts, “HSTP” is just another term for AWTS.
Jargon Tip: In QLD and some parts of NSW, manufacturers or councils may refer to an AWTS as an HSTP, especially in approval documents.
3. AWTS (Aerated Wastewater Treatment System)
AWTS is a type of HSTP that treats wastewater in stages using bacteria and air (aeration). It produces treated effluent suitable for subsurface irrigation (and in some cases, above-ground irrigation if disinfected).
Key Components Include:
Primary chamber (like a septic tank)
Aeration chamber
Clarification chamber
Disinfection (chlorine or UV)
Irrigation pump and irrigation system
Jargon Tip: AWTS systems require ongoing servicing every 3 months by a licensed technician. You’ll often see acronyms like “STS” (Sewage Treatment System) or “Secondary Treatment System” used interchangeably.
Comparison 1: OSSM vs HSTP
| Feature | OSSM | HSTP |
|---|---|---|
| Definition | Regulatory term covering all on-site systems | A type of mechanical treatment plant |
| Example | Septic tank + trench | AWTS |
| Complexity | Can be simple (like septic) | More complex, powered, aerated |
| Use Case | Broad rural applications | Smaller blocks, environmental sensitivity |
| Servicing | Varies by system | Regular (quarterly) servicing required |
Verdict: OSSM refers to the category. HSTP is a type of system within that category—more advanced than basic septic setups.
Comparison 2: AWTS vs Septic Systems
| Feature | Septic System | AWTS |
|---|---|---|
| Treatment Level | Primary only | Secondary (and sometimes tertiary) |
| Effluent Quality | Untreated or partially treated | Highly treated |
| Reuse Options | No reuse; absorbed in trenches | Can be reused in garden irrigation |
| Cost | Lower upfront | Higher upfront + servicing costs |
| Maintenance | Low, desludge every 3–5 years | Quarterly servicing, desludging |
Verdict: AWTS is better for small lots, poor soil, or environmental restrictions. Septic is fine for large rural blocks with suitable soil.
Comparison 3: Advanced STS vs Basic Treatment Systems
Advanced STS stands for Advanced Secondary (or Tertiary) Treatment Systems. These are high-tech units often used in eco-sensitive areas, large commercial sites, or developments where effluent must meet very strict standards (e.g., for discharge into waterways).
Basic Treatment Systems include:
Septic tanks
Conventional AWTS
Sand filters
| Feature | Basic System | Advanced STS |
|---|---|---|
| Tech Level | Low–Medium | High |
| Treatment Quality | Low–Medium | Very high |
| Control/Monitoring | Manual or simple controls | Smart sensors, telemetry, automation |
| Suitability | Homes, farms, large land | Resorts, parks, remote camps, coastal |
| Cost | Lower | Higher capital and maintenance costs |
Jargon Tip: Look for systems compliant with AS/NZS 1546.3:2017 for secondary and tertiary systems. Advanced STS often include UV disinfection, nutrient reduction, or membrane filters.
Comparison 4: Advanced STS vs AWTS
While an AWTS meets the standard for secondary treatment, Advanced STS systems often go a step further with enhanced disinfection, nutrient removal (nitrogen/phosphorus), and smart controls.
| Feature | AWTS | Advanced STS |
|---|---|---|
| Technology | Aerated, chlorinated | Membrane filtration, UV, nutrient filters |
| Output Effluent | Class B or A (varies) | Often Class A+ |
| Regulatory Use | Residential blocks | High-risk sites, commercial, flood zones |
| Remote Monitoring | Rare | Often included |
| Power Requirements | Moderate | Moderate to high |
Verdict: If you need ultra-high quality effluent, e.g., for reusing in toilets, laundry, or discharge into waterways, Advanced STS is worth the investment. For most homes, a high-quality AWTS is sufficient.
Comparison 5: AWWS vs MBR Systems
Let’s define the acronyms first:
AWWS = Advanced Wastewater System – a catch-all term for systems with high-end modular or custom features, often from premium manufacturers.
MBR = Membrane Bioreactor – a system that combines biological treatment with membrane filtration, producing extremely clean effluent (often reusable for toilet flushing, laundry, or even industrial uses).
| Feature | AWWS | MBR |
|---|---|---|
| Definition | Advanced modular or custom STS | High-efficiency membrane treatment |
| Effluent Quality | High | Very high (near drinking water standard) |
| Application | Tailored projects (e.g., eco villages) | Hospitals, reuse schemes, tight sites |
| Space Efficiency | Varies | Compact and scalable |
| Maintenance | Regular but flexible | Requires specialised service |
| Cost | Moderate to high | High upfront + operational costs |
Jargon Tip: MBRs are considered cutting-edge and often used in commercial or high-density housing where effluent quality is critical and space is limited.
Other Common Jargon Explained
Here are a few more terms to watch for when reading quotes, service agreements, or council documents:
Primary Treatment: The first stage—removal of solids and sludge (e.g., septic tank).
Secondary Treatment: Biological treatment using bacteria (e.g., AWTS).
Tertiary Treatment: Additional steps like nutrient removal, UV or chlorine disinfection.
Dispersal Area: The irrigation or absorption field where treated effluent is released.
Subsurface Irrigation: Piping laid below the ground to distribute effluent safely.
Sludge and Scum: Solid waste layers that build up in tanks and must be pumped out.
Desludging: Removing built-up solids from tanks, typically every 3–5 years.
Reactor Chamber: The section of an AWTS where bacteria break down organic matter.
Telemetry System: Remote monitoring to send alerts or data to service providers.
Service Interval: AWTS units typically require servicing every 3 months.
NSW Health Accreditation: All systems used in NSW must meet NSW Health guidelines and be accredited.
Choosing the Right System for Your Property
Here’s how to match a system to your situation:
| Scenario | Recommended System |
|---|---|
| Large rural block with good soil | Septic with absorption trenches |
| Small rural lot or clay soil | AWTS with subsurface irrigation |
| Eco-village or holiday park | Advanced STS or AWWS |
| Coastal or flood-prone land | MBR or elevated STS |
| Reuse for garden or toilets | AWTS (with Class A) or MBR |
| Council requires nutrient removal | Advanced STS with tertiary filter |
Cut Through the Jargon with a Professional Assessment
Choosing a wastewater treatment system is not just about budget or technology—it’s about what works for your land, council rules, environmental goals, and long-term maintenance capacity.
Top Tip: Always get a site-specific wastewater design or assessment before committing. Soil type, slope, lot size, and rainfall all influence system suitability.
Need help? Contact the Eco-Septic team on 1800 808 135 to book a free consultation and let us guide you through approvals, installation, and ongoing maintenance.
