Across New South Wales, not every home is connected to the main sewer network. In rural, regional, and semi-rural areas, on-site wastewater treatment systems are the only way to safely manage sewage.
The two most common systems are:
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Septic Tanks (traditional and low-maintenance)
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Aerated Wastewater Treatment Systems (AWTS) (advanced with secondary treatment)
Choosing the right one depends on property size, soil type, water use, council rules, and budget.
What is an On-Site Wastewater System?
An on-site system is a self-contained sewage treatment unit installed on a property. Instead of sending wastewater to a council sewer line, the system collects, treats, and disposes of it on-site.
Common Features
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Collects wastewater from toilets, showers, sinks, and laundry
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Treats it to reduce health and environmental risks
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Disposes of it safely via trenches, absorption fields, or irrigation systems
Septic Tanks in NSW
How Septic Tanks Work
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Collection: Wastewater enters the tank.
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Separation: Solids settle to the bottom (sludge) and fats float (scum).
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Breakdown: Anaerobic bacteria digest organic matter.
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Effluent Disposal: Liquid effluent flows to absorption trenches in the soil.
Pros
✅ Low maintenance
✅ Lower upfront cost
✅ Long lifespan (especially in concrete models)
Cons
❌ Only primary treatment (not as clean as AWTS)
❌ Regular pump-outs required
❌ Larger land area needed for trenches
Aerated Wastewater Treatment Systems (AWTS)
How AWTS Work
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Collection: Wastewater enters a multi-chamber tank.
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Aeration: Air pumps encourage bacteria that break down waste.
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Clarification: Solids settle out.
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Disinfection: Chlorine or UV sterilises effluent.
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Reuse: Treated water is dispersed via subsurface or surface irrigation.
Pros
✅ Higher treatment quality
✅ Effluent can be reused for irrigation
✅ Smaller land footprint compared to septic
Cons
❌ Higher upfront cost
❌ Requires quarterly servicing (NSW council regulation)
❌ Needs power supply (not ideal in off-grid setups)
Septic vs AWTS: Key Differences
| Feature | Septic Tank | AWTS |
|---|---|---|
| Treatment Level | Primary only | Secondary/Advanced |
| Effluent Use | Absorption trenches | Subsurface irrigation |
| Cost | Lower | Higher |
| Maintenance | Pump-out every 3–5 years | Serviced every 3 months |
| Power Required | No | Yes |
| Council Rules | Simple approval | Mandatory servicing contract |
NSW Council Rules for On-Site Systems
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Approval Needed: Every system must be approved by your local council.
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Service Contracts: AWTS must be serviced every 3 months by a licensed technician.
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Health Guidelines: Systems must meet NSW Health On-Site Sewage Management guidelines.
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Environmental Protection: Effluent disposal must not contaminate groundwater, creeks, or neighbouring land.
Which One is Right for You?
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Choose a Septic Tank if:
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You have plenty of land for trenches
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You want a low-maintenance, lower-cost option
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You don’t need irrigation reuse
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Choose an AWTS if:
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You want to irrigate gardens with treated water
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You have limited land space
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You’re prepared to maintain servicing contracts
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Both septic tanks and AWTS are effective, but they suit different properties and lifestyles. Septic tanks are simple and reliable, while AWTS offer cleaner water and flexibility.
Unsure which system is best for your property?
Talk to Eco-Septic — we design, supply, and maintain both septic tanks and AWTS systems across NSW.
📞 Call 1800 808 135 today for expert advice.
