The types of septic systems used in NSW range from simple concrete tanks with absorption trenches to sophisticated aerated treatment units with UV disinfection, and the system on your block shapes everything from council fees to how often you need a pump-out. This guide covers every on-site sewage management system type you are likely to encounter on a Mid North Coast property, with a plain-English comparison of capital cost, running cost and site suitability. If you are already clear on the basics of how wastewater moves underground, our how a septic system works guide has the detail.
What counts as an on-site sewage management system in NSW?
In NSW, any system that treats and disposes of sewage on the property where it is generated is classified as an on-site sewage management system (OSMS). The term covers everything from a basic septic tank to a fully aerated treatment unit with sub-surface irrigation. The NSW Health advisory note for on-site sewage management sets out the public health requirements, while PMHC on-site sewage management pages specify how Port Macquarie-Hastings Council administers approvals and inspections locally.
All systems require a Section 68 approval to install and a separate approval to operate under the NSW Local Government Act. The system type affects both what the council will approve for a given block and how closely it will monitor the installation once it is running.
Conventional septic tank and absorption trenches
A conventional septic system has two main parts: a buried tank where solids settle and anaerobic bacteria partially break down the waste, followed by a network of perforated pipes in gravel-filled trenches where the clarified liquid (effluent) soaks into the soil. The soil does the final treatment work.
Concrete tanks in the 3,000-5,000 litre range are the most common type on older rural properties across the Hastings, Wauchope and Kendall areas. They are the cheapest system to install and have very low running costs: no electricity, no chemicals, no quarterly service contract. The trade-off is that they need pumping every three to five years and they demand soil that will absorb effluent reliably. Sandy coastal soils around Bonny Hills and Lake Cathie can percolate too fast, allowing insufficiently treated effluent to reach groundwater, which is why councils on the coast often require secondary treatment instead.
Aerated wastewater treatment systems (AWTS)
An aerated wastewater treatment system (AWTS) adds a mechanical treatment stage. After primary settlement in a tank chamber, air is pumped through the effluent to promote aerobic bacterial activity, reducing pathogens and nutrient levels far more than a conventional septic achieves. The cleaner output can typically be used for sub-surface drip irrigation, reducing the land area needed.
AWTS units are very common on new estates near Lake Cathie and on coastal blocks where soil conditions or setback distances rule out conventional trenches. They cost more to buy and install than a standard septic, require a quarterly service by an accredited agent, and run on electricity continuously. Our aerated system servicing covers what that quarterly maintenance involves. For a direct comparison of the two approaches, see septic vs aerated wastewater system.
Sand filter and reed bed secondary treatment
A sand filter sits between the primary septic tank and the final disposal area. Effluent from the tank is dosed intermittently over a graded sand bed, which provides additional biological and physical treatment before the liquid enters the trenches or drip lines. Reed bed (constructed wetland) systems use the same principle but grow wetland plants whose roots enhance biological activity.
These systems are common on older coastal Camden Haven builds where the original soil assessment found marginal percolation or proximity to waterways. They add complexity, cost and an eventual requirement to replace the sand media, but they do not need the continuous electricity input of an AWTS. See our sand filter septic system explained guide for the full breakdown.
Worm farm and composting wastewater systems
Worm farm (vermifilter) systems replace the conventional septic tank and trench arrangement with a bed of composting worms that process raw wastewater. The worms consume organic solids, producing a liquid output that is dosed into subsurface irrigation lines. Composting toilet systems go a step further, treating the toilet waste separately from greywater.
These systems have lower effluent volumes and can work on small blocks, but they carry unique management requirements: the worm population must be kept alive and active, which rules out harsh cleaning products and can be difficult in very cold conditions (less of an issue on the Mid North Coast than in alpine NSW). Councils accept them only if the specific unit appears on the NSW Health accreditation list. Our worm farm septic system guide covers the practical pros and cons in more detail.
Greywater diversion and reuse
Greywater diversion is not a complete sewage management system on its own. It separates laundry and bath/shower water from toilet waste (blackwater), allowing the lower-risk greywater to be reused for garden irrigation or directed to a smaller absorption area. It must be used alongside a septic or AWTS that handles the blackwater.
On the Mid North Coast, greywater systems can reduce hydraulic load on the main system, which extends trench life and reduces pump-out frequency. They require council approval and must be managed carefully to avoid pooling or odours. Our septic rules NSW guide summarises the broader regulatory picture.
Which system suits which Hastings property?
The right system depends on block size, soil type, setback distances to boundaries and watercourses, proximity to reticulated sewer, and how much the owner can budget for installation and ongoing servicing.
| System type | Typical capital cost | Running cost | Suitable soil | Mid North Coast context |
|---|---|---|---|---|
| Conventional septic + trenches | $8,000-$15,000 | Low (pump-out only) | Medium-clay loam with good percolation | Common on rural Wauchope/Kendall blocks 1,000 m+ from water |
| AWTS | $15,000-$28,000+ | Medium (electricity + quarterly service) | Most soils, including clay | Preferred on new coastal estates; required near waterways |
| Sand filter + trenches | $12,000-$22,000 | Low-medium (no electricity but media replacement) | Poor percolation, sandy coastal soils | Older Camden Haven builds; blocks close to estuaries |
| Worm farm system | $12,000-$20,000 | Low-medium (no pump-out but worm management) | Most soils | Niche; accepted where unit is NSW Health accredited |
| Greywater diversion (add-on) | $1,500-$5,000 | Low | N/A (add-on only) | Reduces load on primary system; needs blackwater treatment alongside |
All figures are indicative guide ranges only; get quotes for your specific block and system. Book a septic tank pump-out or get a free assessment to work out what suits your property.
Types of septic systems NSW FAQs
What is the most common type of septic system in NSW?
The conventional concrete septic tank with absorption trenches remains the most common type across rural NSW, including older properties in the Hastings, Wauchope and Kendall areas. AWTS units are now standard for new builds in coastal and peri-urban areas where councils require secondary treatment before disposal.
Can I choose any system I want for a new install?
Not entirely. The system must suit the site: soil percolation tests, setback distances, block size and environmental sensitivity all affect what council will approve. Your plumber or wastewater designer will recommend the options that can get through a Section 68 approval for your specific land.
Do all NSW septic systems need council approval?
Yes. Under Section 68 of the NSW Local Government Act, you need approval to install and a separate approval to operate any on-site sewage management system. This applies to new installs, replacements and major upgrades.
How do I know which system is on my property?
Start with your council’s records, which should show the original Section 68 approval and system type. If you have an AWTS, there will typically be a branded control panel and an alarm on the outside of the house. A conventional septic will have a lid (or lids) at ground level with no electrical components.
Is a worm farm system approved by NSW councils?
Individual worm farm systems need to appear on the NSW Health accreditation list for sewage management facilities before a council will grant a Section 68 approval for them. Not all vermifilter products are on the list, so check accreditation status before selecting a unit.