On rural properties across the Wauchope, Comboyne, King Creek, and broader Hastings hinterland, most households draw drinking and stock water from either an on-site dam, a groundwater bore, or a rainwater tank. Placing a septic system anywhere near these water supplies is one of the most serious mistakes a property owner can make, and one of the most common sources of compliance problems when older rural properties are sold or redeveloped.
NSW regulations under AS/NZS 1547:2012 and the Port Macquarie Hastings Council onsite sewage management framework set minimum setback distances between every component of a septic system and every water source on or near the property. These distances exist because poorly placed systems can contaminate water supplies with pathogens, nitrates, and phosphorus, with serious health consequences.
The Critical Point: Setbacks Apply to Neighbours’ Water Sources Too
A common misconception is that setback rules only apply to your own property. In NSW, setback requirements from septic systems to water supply bores apply to bores on neighbouring properties as well as your own. You cannot place a land application area 100 m from your own bore but only 30 m from the bore on the next lot.
On rural blocks in the Hastings hinterland where bore-dependent properties sit on lots ranging from 5 to 100+ hectares, this is usually not a constraint, there is plenty of room. But on smaller rural-residential lots (2-5 ha) where multiple neighbouring bores may be within 100 m, the effective buildable area for a leach field can be very constrained.
Standard Setback Distances Under AS/NZS 1547:2012
These are minimum setback distances. Port Macquarie Hastings Council may impose greater distances based on site-specific risk assessment:
| Septic Component | To Water Supply Bore | To Dam / Surface Water | To Permanent Waterway | To Intermittent Waterway |
|---|---|---|---|---|
| Septic tank (conventional) | 15 m | 6 m | 6 m | 3 m |
| Absorption / leach drain area | 100 m | 50 m | 50 m | 25 m |
| AWTS drip irrigation area | 30 m | 15 m | 15 m | 8 m |
| Mound system | 100 m | 50 m | 50 m | 25 m |
| Pump/dosing chamber | 15 m | 6 m | 6 m | 3 m |
The dramatically different setbacks between conventional leach drains and AWTS drip irrigation areas reflects the difference in effluent quality. Primary effluent from a conventional septic contains significant pathogen loads and requires a long soil travel distance for natural attenuation before it could reach a water source. Class B AWTS effluent has already had 90%+ pathogen reduction and disinfection, the remaining risk at 15 m from a waterway is much lower.
Dams on Rural Properties
Farm dams are particularly common on larger rural properties around Comboyne, Byabarra, and the upper Hastings valleys. A dam used for stock or domestic supply creates a significant constraint on where the land application area can go.
Key considerations for dams:
Multiple dams: If you have more than one dam, every dam is a constraint point. Map all water sources on the property before positioning any part of the septic system in the design.
Seasonal dams: Even if a dam is dry for 8 months of the year, it counts as a surface water source and setbacks apply. Intermittent waterway setbacks still apply at 25 m from the leach drain.
Dam inlet catchments: The effective protection zone around a dam includes not just the dam wall and water body, but the catchment that drains into it. Placing a leach field upslope of a dam (even outside the 50 m setback) can still allow nutrient-laden effluent to reach the dam through subsurface lateral flow during wet periods. Hydrological assessment may be needed for complex sites.
Neighbour’s dam: The same setback distances apply to a dam on an adjacent property that is clearly visible across the fence.
Rainwater Tanks
NSW guidelines distinguish between rainwater tanks and bores (groundwater), rain tanks collecting roofwater are not treated as “water supply bores” for setback purposes, but they are still water supplies and should be protected.
The practical guidance is to maintain a minimum 3 m separation between any part of the septic system and a rainwater tank. This primarily protects against contamination from overland flow or spillage rather than groundwater contamination.
If the rainwater tank is a primary drinking water supply and is downslope of the proposed land application area, more consideration is warranted, ensure no stormwater diversion from the septic area drains toward or near the tank.
Waterway Setbacks Along the Hastings and Camden Haven
Properties bordering the Hastings River, its tributaries, Camden Haven River, Queens Lake, and other waterways face significant setback constraints. The 50 m setback from a permanent waterway to a conventional leach drain is measured from the top of the bank, not from the current water’s edge, and applies at all flow levels.
In practice, on a river-front property where the dwelling is close to the bank:
- The septic tank can usually be sited legally at 6 m from the bank
- The land application area must be at least 50 m from the bank
- On a shallow alluvial floodplain block, this 50 m zone may encompass most of the usable flat land on the property
In these situations, options include:
- Upgrading to AWTS with drip irrigation (15 m setback rather than 50 m)
- Using the rear portion of the block (further from the waterway) for the land application area, with a pump system to move effluent there
- In extreme cases, elevated mound systems
If you have a property near a waterway and are trying to fit a septic system within the setback constraints, contact us for a consultation, this is exactly the type of site constraint we navigate regularly.
How to Confirm Your Property’s Water Source Setbacks
Before lodging a DA for a new or modified septic system, map all water sources on and adjacent to the property:
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Locate your own bore(s): Check your property records for bore registration details. If you don’t know your bore location, a hydrogeologist or well driller can advise.
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Locate all dams and surface water: Walk the property and map all dams, seasonal watercourses, drainage channels, and wetlands. Identify which are permanent and which are intermittent.
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Check neighbouring bores: NSW’s DEFS water bore register (available online) shows registered bores. Search the register for bores within 200 m of your proposed land application area.
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Identify mapped waterways: Council’s GIS mapping shows mapped permanent and intermittent waterways. These are the reference lines for setback measurement.
This information is essential input for the site assessment and percolation test that your consultant will prepare for the DA.
Retrofitting an Old System That Violates Current Setbacks
Many rural properties in the Hastings hinterland have older septic systems installed in the 1970s, 1990s that predate current setback requirements and may not comply with current standards. If a system was legally installed under the rules at the time, it generally has existing-use rights and does not need to be immediately moved.
However, when:
- The property changes hands (triggering a potential audit)
- A modification to the system is proposed
- The system fails and replacement is required
- Council conducts a compliance audit under the NSW Septic Safe program
…the new installation or modification must comply with current setback standards, even if the old system did not.
This can present genuine challenges on properties where the available area for a compliant land application is constrained by water sources. Early engagement with Council and a professional site assessment before replacement is essential.
FAQ
How is the 100 m bore setback measured for a conventional leach drain? It is measured from the nearest edge of the land application area (the absorption trench or leach drain) to the nearest point of the water supply bore casing. It is not measured from the centre of the system or from the tank, the full extent of the leach drain area must be within the setback.
My property has a bore but I don’t drink the water, does the setback still apply? Yes. Setback requirements are applied regardless of whether the bore is currently used or connected. The bore may be used in future, or by future owners. Council requires setbacks to be met based on the existence of the bore, not its current use.
Can I get a Council exemption from setback requirements? In some circumstances Council has discretion to accept reduced setbacks where an applicant can demonstrate through detailed hydrogeological assessment that the risk of contamination is negligible. This is uncommon and requires expert evidence, it is not a simple request. It’s almost always more cost-effective to design a system that complies with standard setbacks.
Can I cap or deregister my bore to remove the setback constraint? In theory, a bore that is properly decommissioned in compliance with NSW bore decommissioning requirements removes that constraint. However, if water from the bore is used for domestic supply, decommissioning it without another water source creates a different problem. Get professional advice before pursuing this path.
My new system needs to go where there’s currently a dam, can I drain and fill the dam? Potentially, but dam removal has its own approvals pathway through NSW DPI Water. The dam may be an approved water use under a water licence, which complicates things further. This is a site-specific question that requires legal and planning advice.
Need an honest assessment of what your rural property can accommodate for an onsite sewage system given your dams, waterways, and bore locations? Send an enquiry; this site’s guides are written for the Hastings hinterland and set out the options.