The new septic system install cost in NSW is rarely a single number. It is the sum of a chain of professional services and materials, each with its own price range, and the final total depends heavily on site conditions. As a broad starting point, a conventional septic system on a straightforward block in the Hastings region typically costs somewhere between $8,000 and $18,000 all up. An aerated wastewater treatment system (AWTS) on the same block typically runs from $15,000 to $28,000 or more. Both ranges can blow out significantly on difficult sites. This guide breaks down where the money goes so you can sanity-check a quote and ask the right questions. For the complete approval process behind any new install, see our Section 68 approval guide.
The line items in a new septic install
Before any excavation starts, a new septic install requires professional and approval costs that many owners underestimate. The full cost chain looks like this:
- Wastewater management report (consultant fee)
- Section 68 approval application fee (council)
- Tank supply and delivery
- Trench materials (aggregate, perforated pipe, geotextile, inspection risers)
- Excavation (tank pit and trench lines)
- Licensed plumber installation and commissioning
- Electrical connection (for AWTS pump and alarm)
- Landscaping and site reinstatement
Each of these line items is discussed below with indicative ranges. All figures are general guides and subject to quote. Site conditions, access, distance from suppliers and individual contractor pricing all affect the final cost. Ask your plumber to itemise the quote so you know what is included.
Wastewater management report and Section 68 approval fees
A wastewater management report from a qualified consultant is typically required by PMHC before they will assess a Section 68 application for a new install. The report covers soil percolation testing, setback assessments, system sizing and a recommendation on system type. Indicative cost: $800-$2,500 depending on the complexity of the site and whether multiple soil tests are needed.
The Section 68 application fee is set by PMHC in their annual fees and charges schedule. Rather than quoting a specific fee that may be out of date, check the current PMHC on-site sewage management page for the current fee. There may be separate fees for the approval to install and, later, the approval to operate.
Total pre-build professional and approval costs typically range from $1,200-$3,500 depending on site and council fees.
Tank and trench materials
Conventional septic tank: The tank itself is one of the more predictable line items. For a standard residential polyethylene tank of 3,000-4,500 litres (appropriate for a 3-4 bedroom home), supply-only prices typically range from $900 to $2,500 depending on capacity and material. Concrete tanks are heavier and more expensive to deliver to remote sites but may be specified for high-water-table locations. For detail on material options and their relative costs, see the tank materials comparison.
AWTS unit: AWTS units are more complex than a passive tank and are priced accordingly. Supply-only costs for a domestic AWTS unit of appropriate capacity typically range from $4,500 to $9,000. The unit must be from the NSW Health accredited list.
Trench materials: A standard absorption trench installation requires coarse gravel aggregate (typically around 0.5 m3 per lineal metre of trench), perforated 100mm or 150mm pipe, geotextile filter fabric and inspection risers at each end. For a 3-bedroom home, typical trench lengths range from 60-150 metres of aggregate trench depending on soil percolation rates. Material costs for the trench component alone typically run $2,000-$6,000 depending on trench length.
Excavation, plumbing and commissioning
Excavation is one of the most variable costs because it depends on:
- Soil type (hand-dig sand vs machine-dig rock)
- Access for the excavator (tight blocks, overhead obstructions, distance from the road)
- Trench depth (deeper installation in high water table areas means more excavation)
- Distance from the house to the tank and trench field
Indicative excavation costs for a standard residential install: $1,500-$5,000.
Licensed plumber labour for installation, pipe connections, inspection opening fitting, and commissioning typically ranges from $2,500 to $6,000 for a standard install. Electrical connection for an AWTS (alarm panel, pump wiring) adds a further $500-$1,500.
Re-instatement of disturbed ground, including topsoil replacement and seeding or turfing, is sometimes included in the quote and sometimes an extra.
Typical all-in ranges: conventional septic vs AWTS
The table below summarises indicative all-in ranges for a typical residential install on a reasonably accessible Mid North Coast block. These are guides for planning purposes, not fixed quotes. Your actual cost may be higher or lower depending on site-specific factors.
| Component | Conventional septic | AWTS |
|---|---|---|
| Wastewater management report | $800-$2,000 | $1,000-$2,500 |
| Section 68 approval fee | $250-$600 | $250-$600 |
| Tank supply | $900-$2,500 | $4,500-$9,000 |
| Trench materials | $2,000-$6,000 | $2,000-$5,000 |
| Excavation | $1,500-$5,000 | $1,500-$4,500 |
| Plumber/commissioning | $2,500-$5,000 | $3,000-$6,000 |
| Electrical (AWTS only) | n/a | $500-$1,500 |
| Indicative all-in | $8,000-$18,000+ | $15,000-$28,000+ |
Note: These ranges exclude rock removal, major access remediation, secondary treatment add-ons (e.g. chlorination for AWTS), or any pump and rising main for sites where the system cannot gravity-feed. Large blocks with long trench runs, or sites requiring elevated mound systems due to high water table conditions, will typically sit at the higher end or above these ranges.
For AWTS specifically, the ongoing quarterly service contract (typically $200-$350 per quarter, see our AWTS service cost guide) is a real ongoing cost that should be factored into the lifetime comparison with conventional septic, which requires a pump-out every 3-5 years.
How site conditions change the price
The two biggest variables that push an install toward the top (or beyond the top) of the ranges above are:
Rock: If the excavation hits rock in the tank pit or trench lines, the cost increases significantly. Rock breaking or blasting is expensive and may require a variation on the original quote. On properties in hilly or elevated terrain around the Hastings, this is a real risk worth asking the plumber about during the quoting stage.
Access: If the excavator cannot get to the tank installation area directly (tight driveway, bridge weight limit, dense vegetation), the plumber may need to use smaller equipment or hand-dig sections, which adds significantly to labour cost. Remote blocks with dirt track access around Wauchope or Kendall can be more expensive simply due to truck and equipment access.
High water table or mound system requirement: If the wastewater management report concludes that the water table is too high for standard trenches and a raised mound system is required, the cost of fill material and additional engineering can add $3,000-$8,000 to a conventional install.
Old tank decommissioning: If there is an existing tank that needs to be pumped out and either removed or crushed and filled before the new system goes in, this adds $800-$2,500 depending on tank size and condition.
Other system types, including worm farm systems and sand filter systems, have their own cost profiles and site requirements. Get separate quotes if you’re comparing system types based on the wastewater consultant’s recommendations.
New septic install cost FAQs
Do I need a wastewater management report for every new install?
Yes, in practice. PMHC and most NSW councils will not process a Section 68 application for a new install without a wastewater management report from a qualified consultant. The report establishes that the chosen system type and location are appropriate for the site’s soil conditions, environmental context and setback constraints.
Can I save money by supplying the tank myself?
Some licensed plumbers will work with a client-supplied tank, but this creates complications if there are warranty issues or if the tank is not appropriate for the site conditions identified in the wastewater report. Most plumbers include tank supply in their quotes and build in their supplier relationships. Ask the question when getting quotes.
How long does the whole process take from decision to commissioning?
On a straightforward site, the full process from commissioning the wastewater management report through to commissioned system typically takes 8-16 weeks. Council assessment times for Section 68 applications vary. On complex sites or during busy council periods, the pre-approval phase alone can take 3-4 months.
Is an AWTS always more expensive to own over time than a conventional septic?
On a total-cost-of-ownership basis, AWTS is typically more expensive in running costs (quarterly service contracts of around $800-$1,400 per year) compared to a conventional tank’s 3-5 year pump-out cycle. However, on sites where the council requires an AWTS for environmental reasons, the comparison is not between AWTS and conventional but between AWTS and not having any system at all.
Can I connect to sewer instead of installing a new system?
On some properties within or adjacent to the Port Macquarie township, a sewer connection may be available from NSW water utilities. Our septic vs sewer connection guide covers how to find out whether sewer is available and what connection typically costs.