Is my house in a flood zone? How to check in NSW
Whether you're buying, building, or just curious, knowing your flood risk matters. Here's how to check for free using government data — and what the results actually tell you.
What “flood zone” means in NSW
In NSW, there's no single official “flood zone” designation. Instead, there are several overlapping layers of flood information, each with a different purpose:
- Flood Planning Area (FPA) — defined in the Local Environmental Plan (LEP). This is the statutory boundary that triggers planning controls. If your property is inside the FPA, development applications will need to address flood-related clauses.
- Flood Control Lot — a property that the Planning Portal identifies as affected by flood-related LEP provisions. You can check this via the NSW Planning Portal's property search.
- Flood study extent — the area modelled in a council flood study. These studies calculate how deep water gets at different flood frequencies (e.g. 1-in-100 year event). Not all areas have detailed flood studies.
- Flood prone land — a broader category used in the NSW Flood Prone Land Policy. Land is “flood prone” if it can be inundated by the Probable Maximum Flood (PMF) — an extreme theoretical event.
A property can be “flood prone” without being in the Flood Planning Area, and vice versa. The FPA is the one that matters most for planning approvals and is typically based on the 1% AEP (1-in-100 year) flood plus a freeboard allowance (usually 0.5m).
How to check: step by step
There are three free ways to check flood status for any NSW property. Each gives you different information.
1. NSW Planning Portal — property search
Go to the NSW Planning Portal (planningportal.nsw.gov.au) and use the property search tool. Enter any NSW address. The portal returns a list of planning constraints, including whether the property is a “Flood Control Lot” under the LEP.
What it tells you: Whether the LEP applies flood-related clauses to this property. This is a yes/no answer — it doesn't tell you how deep the water gets or how often it floods.
2. Section 10.7 Planning Certificate
When buying property, your conveyancer will order a s10.7 certificate from the local council. This is a legal document that lists all planning controls affecting the property. Clause 7 covers “flood related development controls.”
What it tells you: The same binary flood status as the Planning Portal, but in a legally binding document. If flood controls apply, the certificate says so. If they don't, it says “no” — and the council is liable for that statement.
What it doesn't tell you: Flood depth, frequency, historical flood events, insurance implications, or whether the property flooded in past events. Many buyers assume the s10.7 gives a complete picture. It doesn't.
3. Council flood maps and flood studies
Some councils publish flood study data on their websites or through the NSW SES. These studies model flood behaviour for specific catchments — how deep the water gets, how fast it flows, and how often flooding of different severity occurs.
What it tells you: Actual flood depth and extent at different return intervals. For example, in a 1-in-100 year flood, this property would experience 0.3m of water. In a 1-in-500 year flood, 1.2m. This is the most useful information for understanding real flood risk.
The catch: Not all councils have detailed flood studies. Where they exist, they can be hard to find and interpret. Studies are often published as PDF reports with GIS layers that require specialist software to read.
Understanding ARI return periods
Flood studies describe flood severity using Average Recurrence Intervals (ARI) — sometimes called Annual Exceedance Probability (AEP). These are statistical measures, not predictions.
| ARI | AEP | What it means |
|---|---|---|
| 1-in-20 year | 5% | 5% chance of this level happening in any given year. Common enough that you'd likely experience it during a 30-year mortgage. |
| 1-in-50 year | 2% | Less frequent, but a 45% chance of occurring at least once in 30 years. |
| 1-in-100 year | 1% | The standard used for flood planning areas in NSW. Still a 26% chance over 30 years. |
| 1-in-500 year | 0.2% | Rare but catastrophic. Used for emergency planning. The Hawkesbury-Nepean has had events near this magnitude. |
A common misconception: “1-in-100 year flood” does not mean it only happens once every 100 years. It means there's a 1% chance in any given year. Over a 30-year mortgage, there's roughly a 1-in-4 chance it happens at least once. The Hawkesbury-Nepean experienced two major floods within three years (2021 and 2022).
What flood status means for insurance
Insurance companies use their own flood models — they don't simply rely on the LEP flood planning area. An insurer might consider a property “flood exposed” even if the council doesn't, or vice versa.
That said, if your property is in an LEP flood planning area, you should expect:
- Higher insurance premiums — typically $1,000-$5,000 more than comparable non-flood properties
- Higher excess for flood claims — some policies set flood excess at $10,000+
- In severe cases, flood cover may be excluded from your policy entirely
The most important thing you can do is get an insurance quote before you buy. Call at least two insurers with the specific address and ask for a quote including flood cover. The premium will tell you more about real flood risk than any planning certificate.
What flood status means for building
If your property is in a flood planning area, any development application will need to address the flood-related clauses in the LEP and DCP. Typically, this means:
- Minimum floor levels — habitable floors must be above the 1% AEP flood level plus freeboard
- Building materials — below the flood planning level, materials must be flood-compatible (no plasterboard, carpet, etc.)
- Structural design — buildings must withstand flood forces (hydrostatic and hydrodynamic loads)
- Evacuation — the site must have a viable evacuation route that doesn't require crossing floodwater
- Storage — no storage of hazardous materials below the flood planning level
These requirements can add $50,000-$200,000 to construction costs depending on the flood depth and the type of development. For renovations, they can make otherwise straightforward projects significantly more complex.
The gap between “flood zone” and actual risk
The biggest limitation of the standard flood zone check is that it's binary — yes or no. But flood risk is a spectrum. A property with 0.1m of water in a 1-in-100 year flood has a very different risk profile from one with 2m of water. Both would show as “flood zone: yes” on a s10.7 certificate.
Equally, a property just outside the flood planning area boundary isn't necessarily safe. The boundary is drawn at a specific flood level (usually 1% AEP + freeboard), and it represents a modelling output with inherent uncertainty. Climate change is also shifting these boundaries — the current flood planning level was calculated using historical rainfall data that may not reflect future conditions.
What you actually want to know is: how deep does the water get at my specific address, and how often? That requires flood study data — the modelled depth at different ARI return periods — not just the binary overlay.
Check flood risk for any NSW address — free instant results
PlotDetect's free Flood Risk Check goes beyond the binary yes/no. Where flood study data is available, it shows modelled depth at 1-in-20 through 1-in-500 year return intervals — plus LEP flood overlay status from the NSW Planning Portal. No account required.
Check flood risk — free