Plenty of properties across Port Macquarie-Hastings run a septic system installed well before 1998, sometimes decades before, under approval frameworks and construction standards that have since moved on considerably. An old system that’s never caused a visible problem is not automatically a system that needs upgrading. What actually forces an upgrade is one of a handful of specific triggers, and knowing what they are (and what an upgrade indicatively costs) is useful whether you’re planning ahead or have just been told by a solicitor, a buyer or the council that yours is one of them.
Why 1998 is a useful marker, not a hard deadline
There isn’t a single date in NSW law that automatically invalidates a septic system installed before it. What has genuinely changed since the 1990s is the regulatory framework around onsite sewage management: the current On-Site Sewage Management approval regime, the Local Government (General) Regulation, and the design standards in AS/NZS 1547 have all been progressively tightened, and most councils, including Port Macquarie-Hastings Council (PMHC), now expect any system coming up for a decision point to meet current standards rather than the standards that applied when it was installed.
That’s the practical reality worth understanding: an old system that’s registered, approved and causing no problems can often keep operating under its existing approval indefinitely, a principle sometimes loosely called “existing use.” But the moment one of the triggers below applies, the conversation usually shifts from “is it working” to “does it meet today’s requirements,” and that shift can be expensive if you’re not expecting it.
What actually triggers a mandatory upgrade?
1. Property sale and disclosure. Septic system status is disclosed as part of conveyancing, and while a Section 10.7 planning certificate mainly confirms registration status rather than physical condition, a pre-purchase inspection that finds a failing or clearly undersized system gives a buyer real negotiating leverage, and can make upgrade-before-settlement a condition of the contract. See our Section 10.7 septic disclosure guide for how this plays out in practice.
2. Renovation or added bedrooms. Extending a house or adding bedrooms increases the design occupancy the system has to handle. Council approval for most renovations that affect occupancy will ask whether the existing OSSM system is adequately sized, and an old system approved for a three-bedroom cottage frequently isn’t sized for the five-bedroom version of the same house.
3. Change of use, including holiday letting. Converting a property to short-term rental use changes its effective occupancy load from what the system was originally approved for. Councils, PMHC included, are increasingly scrutinising this, and an old system that coped fine under permanent occupancy can be pushed well past its design capacity by weekend and holiday-period guest numbers.
4. A non-compliance notice or failed inspection. If council issues an order following a complaint, an audit or a visible failure (surfacing effluent, odour complaints, a collapsed absorption area), the response required is often a full upgrade rather than a repair, particularly for a system old enough that spare parts or matching components are no longer available. Our responding to a non-compliance notice guide covers what that process looks like.
5. Subdivision or new development on the same lot. Subdividing land, or building a second dwelling, generally requires a fresh assessment of onsite sewage capacity for the whole site, and an old single system serving what becomes two titles is a common trigger for a full upgrade.
6. Proximity to a waterway or sensitive area being reclassified. Where mapping of a sensitive waterway buffer changes, or where a system’s actual distance from a watercourse comes under scrutiny for the first time, a conventional system that was compliant decades ago can find itself needing a higher-treatment AWTS to meet current setback and effluent-quality requirements.
What the upgrade process actually involves
An upgrade generally follows the same path as a brand-new installation: a site and soil assessment by a suitably qualified person, a system design that meets current PMHC and AS/NZS 1547 requirements, a lodged OSSM application, and (for aerated systems particularly) confirmation of the ongoing service contract obligations before approval is granted. Our PMHC on-site sewage management approval guide walks through that process step by step; processing typically takes several weeks once a complete application is lodged. The old system then needs to be properly decommissioned rather than simply abandoned in the ground, pumped out, cleaned, disconnected and either broken up and filled or removed, depending on the tank type.
What does an upgrade cost?
Costs vary a lot by system type, site conditions and how much of the existing infrastructure can be reused. As a general guide across the Port Macquarie-Hastings region:
| Item | Indicative range |
|---|---|
| Site and soil assessment | $800-$2,500 |
| OSSM application and council lodgement fee | $1,500-$3,500 |
| Decommissioning the old tank (pump-out, clean, fill or remove) | $2,000-$9,400 |
| New conventional septic + absorption trench, simple site | $9,000-$18,000 |
| New AWTS + drip irrigation, coastal or constrained site | $18,000-$28,000 |
| Complex AWTS install (near waterway, engineered fill) | $25,000-$35,000+ |
These are indicative guide ranges only, not quotes, and every figure depends heavily on soil conditions, access, tank size and whether existing components can be reused. Our septic pump-out cost guide covers ongoing servicing costs once a new system is in, which run quite differently for a conventional tank versus an AWTS.
What to do if you suspect your system may need an upgrade
- Check what’s actually registered. Contact PMHC’s Development and Environment team with your address to confirm what system is on file and whether there are any existing orders or conditions.
- Book an inspection before you assume the worst (or the best). A septic inspection gives you the physical condition, separate from the paperwork question, and is a fraction of the cost of a full upgrade.
- Get the trigger clear before you spend money. A renovation, a sale or a subdivision each has slightly different requirements; knowing which one applies avoids paying for the wrong assessment.
- Budget for decommissioning, not just the new system. It’s a genuine line item that’s easy to forget when comparing quotes.
Pre-1998 septic upgrade FAQs
Does my old septic system automatically become illegal after a certain date?
No. There’s no single date that invalidates an existing, registered, working system in NSW. What changes things is one of the specific triggers above, sale, renovation, non-compliance, subdivision or a use change, at which point current standards generally apply to whatever work follows.
Can I just replace a failed old tank with a like-for-like new one?
Not always. Even a like-for-like tank replacement requires OSSM approval, and depending on your site and the current mapping around waterways or water tables, council may require a higher standard than the original approval, sometimes an AWTS instead of a conventional tank.
How long does an upgrade take from decision to completion?
Allow several weeks for the site assessment and design, several more for council assessment and approval, then installation itself typically takes days rather than weeks once approved. A straightforward conventional upgrade can move faster than a constrained AWTS install requiring engineering input.
Is there any funding or rebate for septic upgrades in NSW?
Generally no direct funding for private septic upgrades; maintaining and upgrading an onsite sewage system is the property owner’s responsibility. Check with PMHC directly in case any local program applies to your specific circumstances.
What happens if I ignore a trigger and don’t upgrade?
Depends on the trigger. Ignoring a non-compliance notice can lead to further orders and, in serious cases, penalties. Selling without disclosing a known issue creates conveyancing risk. Renovating without addressing an undersized system can hold up a Construction Certificate. None of these tend to resolve themselves by waiting.
Get advice on your upgrade
If you think your property might be facing one of these triggers, start with an inspection rather than a guess. Get a free quote and tell us your situation, sale, renovation, a council letter or just an old system you’re planning ahead for, ; working out what applies is exactly what the enquiry is for.