Upgrading from a conventional septic system to an Aerated Wastewater Treatment System (AWTS) is a significant investment for Hastings region property owners. But it’s also a step that PMHC increasingly requires, either when an existing system fails, at the time of renovation or subdivision, or when a property’s environmental setting demands a higher standard of treatment. Understanding what drives the cost helps you budget accurately and avoid surprises.
Quick answer (BLUF)
A typical AWTS upgrade in the Port Macquarie-Hastings region costs $18,000 to $35,000 installed, depending on system capacity, site access, the absorption area required, and whether existing infrastructure can be reused. The AWTS unit itself is $8,000 to $15,000; the remaining cost is site works, electrical connection, new absorption area, and PMHC approval. Ongoing costs include a mandatory quarterly service contract ($400 to $700/year) and electricity (~$200 to $400/year).
Why properties upgrade to AWTS
Not every septic owner chooses an AWTS upgrade, it’s often required. The triggers in the Hastings region include:
System failure: A failed conventional system that cannot be repaired within the existing footprint, or where there’s no suitable land for new conventional trenches, often leaves AWTS as the only option.
PMHC-mandated upgrade: When applying for development consent (renovation, extension, subdivision, change of use to holiday rental), PMHC may require the on-site sewage management system to be upgraded to current standards, which may mean AWTS.
Environmental sensitivity: Properties adjacent to the Hastings River, coastal lagoons, or within the catchment of sensitive waterways may be required to treat to Class 2 or better, a standard conventional systems can’t achieve.
Constrained site: Where the available land for a conventional absorption area is insufficient (small lots, competing setbacks), an AWTS with its smaller absorption footprint can make the site work where conventional trenches cannot.
Holiday rental conversion: Converting to Airbnb or short-stay rental may require an OSSM upgrade to match the maximum occupancy, which on many coastal Hastings properties translates to AWTS requirement.
Breaking down the costs
The AWTS unit
Modern AWTS units for residential use are typically designed for households of 2-10 equivalent persons (EP). Common size combinations in the NSW market:
- 6-EP unit: $8,000 to $11,000 supply only
- 10-EP unit: $10,000 to $14,000 supply only
- 15-EP (large household/holiday rental): $13,000 to $18,000 supply only
Unit prices vary by brand, supplier, and current market conditions. Always compare installed costs, not just unit price.
Excavation and tank installation
Installing the AWTS tank requires excavation, bedding material, and backfill. On most Hastings rural properties, standard excavator access is available, keeping this cost moderate. Rocky sites (particularly on the Comboyne Plateau or hinterland) or very wet ground can significantly increase excavation costs.
Typical excavation and installation: $2,000 to $5,000
Electrical connection
AWTS units require 240V power for the air compressor, pump, and UV disinfection (if fitted). If the site already has power at the proposed tank location, connection cost is minimal. On remote blocks or properties where the tank is far from the switchboard, cable run costs can add $1,500 to $4,000.
New absorption area
An AWTS producing Class 2 effluent requires a smaller absorption area than a conventional system, but the area must be newly constructed to match the AWTS dispersal requirements. Options include:
- Subsurface drip irrigation: The most common pairing with AWTS in the Hastings region. Plastic drip tubing is laid in shallow trenches or on the surface under mulch. Cost: $4,000 to $8,000 depending on area required.
- Conventional absorption trenches (new): Can still be used with AWTS effluent. Cost: $4,000 to $10,000.
- Spray irrigation: Less common near dwellings due to setback requirements, but used on larger rural blocks. Cost: $3,000 to $7,000 for the irrigation component.
PMHC approval
OSSM approval for an AWTS installation requires a site assessment, system design, and application lodgement. Professional fees for the assessment and design: $1,500 to $3,500. PMHC application fees: check current schedule (typically $300 to $600).
Decommissioning the existing system
The old septic tank usually needs to be decommissioned (pumped, broken or pierced, and backfilled) if it’s not being repurposed as a pre-treatment holding tank. Cost: $500 to $1,500.
Total typical installed cost range
| Scenario | Estimated range |
|---|---|
| Straightforward conversion, good access, 6-EP AWTS | $18,000 to $24,000 |
| Mid-complexity conversion, 6-10 EP, new drip irrigation | $22,000 to $30,000 |
| Complex site (rocky, remote, constrained), 10-EP+ | $28,000 to $40,000+ |
Ongoing costs: what AWTS adds to your annual budget
Mandatory service contract: A licensed AWTS service provider inspects the unit quarterly. Average cost: $400 to $700 per year depending on provider and location (remote Hastings sites may attract a distance surcharge).
Electricity: Air compressors and pumps run continuously. Annual electricity cost: $200 to $400 depending on unit type and local tariff.
Component replacement: Air pumps, UV lamps, filter media, and UV sensor cells have finite service lives. Budget $200 to $600 every few years for component replacement.
Total AWTS ongoing cost: approximately $800 to $1,500/year compared to conventional septic’s $200 to $500/year (based on 3-5 year pump-out intervals).
Is the upgrade worth it?
For many Hastings properties, the answer is dictated by compliance, you upgrade because you have to. But there are genuine benefits:
- AWTS effluent quality is substantially better, reducing environmental impact on the Hastings catchment
- Smaller absorption area requirement is valuable on constrained lots
- Higher-quality systems can potentially allow reuse of treated effluent for garden irrigation, reducing water consumption
- AWTS systems generally have longer total system lifespans because the higher-quality effluent is gentler on the absorption area
FAQs
Can my existing septic tank be reused as a pre-treatment stage for an AWTS?
Sometimes. If the existing tank is structurally sound and properly sized, some AWTS installers can use it as the primary settling chamber, with the AWTS unit installed downstream. This can reduce costs by $2,000 to $4,000. An inspection of the tank condition is required to confirm suitability.
How long does the AWTS upgrade approval and installation take?
Allow 6-10 weeks from initial consultation to completed installation: 2-3 weeks for soil assessment and system design, 4-8 weeks for PMHC approval, 1-3 days for installation once approval is granted. Timelines can extend at the PMHC approval stage if additional information is requested.
Do I need to keep the service contract active even if the AWTS is working fine?
Yes. The service contract is a condition of your OSSM operating approval, it is not optional. A lapsed service contract is a breach of your approval and PMHC can issue a compliance notice. It also voids most AWTS manufacturers’ warranties.
Can I get grants for AWTS upgrades in NSW?
There are no current NSW-wide grants specifically for residential AWTS upgrades. Some council environmental programs have offered subsidies in the past, check directly with PMHC for any current incentives. For rural properties, some AWTS upgrades may qualify for Small Business or primary production grants if the property has agricultural use.