How to Check Flood Risk Before Buying a House in Australia

Around 1.4 million Australian properties carry some flood risk, and roughly 319,000 of those face at least a 2% chance of flooding in any given year. Those are the Insurance Council of Australia's own numbers, and its members can look up exactly where your address sits. You cannot. The Council licenses a National Flood Information Database to insurers, overlaying government flood mapping onto Australian addresses, and no amount of money gets a buyer in. So the insurer who quotes you on Monday already knows more about the house you inspected on Saturday than you do.

Most of that gap you can close yourself in an afternoon, out of public records the vendor has no say over. Order the council planning certificate and read the hazard notations, check the state or council flood map at address level, compare the floor level to the benchmark that applies to houses, read the building itself for flood evidence, ask the agent in writing whether the property has flooded, and get three insurance quotes on the exact street address before you exchange. Below: what the discount actually looks like in sale prices, each step in full, what a vendor or agent must legally tell you in your state, and the finance angle almost nobody prices in, which is that an uninsurable house tends to become an unmortgageable one.

How much does flood risk cut a property's value?

What a 1-in-100-year flood zone actually means

A 1-in-100-year flood zone, properly the 1% Annual Exceedance Probability (AEP) zone, is land with a 1% chance of flooding in any given year. It is not a once-per-century event. A 1% annual chance compounds: over a 30-year mortgage there is roughly a 26% chance of at least one such flood, and about 55% over an 80-year building life. That is a coin toss on the house your children might inherit.

Researchers at the University of Technology Sydney produced the closest thing Australia has to a clean number. Analysing 6,294 house sales at Richmond, Hobartville and North Richmond on the Hawkesbury-Nepean floodplain between January 1991 and October 2023, they found homes inside the 1% AEP zone sold at a 10.8% discount. Homes in the 1-in-500 zone sold 4.4% below. Homes in the 1-in-1000 zone sold at no discount at all. The authors read that flat 1-in-1000 result as a cognitive limit: past roughly the 1-in-500 level, buyers stop pricing flood risk at all, because the number stops feeling real.

The authors then run the discount out against the cost. On a Richmond median house price of $825,000 in 2023, they calculate an $89,100 discount, which annualises to a modelled flood insurance premium of about $4,606 over 70 years at 5%. On their figures the discount is roughly the price of the risk, handed over upfront, and only where buyers can see the risk at all. The market is reimbursing you at cost for a bill that has not arrived. One caveat they flag: only 37 of those 6,294 sales sat in the highest-risk zone.

Which flood-hit towns recovered: Lismore vs south-east Queensland

The catastrophist version of this story does not survive contact with the data. Cotality's four-year review of the February 2022 east coast floods, published in February 2026, found flood-affected coastal south-east Queensland suburbs typically rebounded within 18 months and now sit about 31% above pre-flood values. Lifestyle demand simply overwhelmed the flood signal.

Inland was different. Cotality's flood-affected Northern Rivers group, being Lismore, Ballina, Mullumbimby, Casino and Kyogle, remains more than 5% below early 2022 levels four years on. Treat the far larger falls circulating online carefully: they are private modelled estimates rather than official valuations, and Lismore's median has since been pushed up by buybacks removing the worst-exposed houses from the market.

So the honest summary is repricing and composition change, not permanent destruction. It also makes the market a useless early warning system. Coastal Queensland forgot inside eighteen months.

How to check flood risk before you buy: a step-by-step workflow

1. Pull the planning certificate and read the hazard notations properly. In NSW this is the section 10.7 planning certificate, renamed from section 149 on 1 March 2018. Order the 10.7(2) for the prescribed matters and, critically, the 10.7(5) too, because that is where councils commonly place actual flood levels and floodplain detail. Under Schedule 2 of the Environmental Planning and Assessment Regulation 2021, the council must note whether the land sits in the flood planning area, or between that area and the probable maximum flood. Other states issue equivalent certificates.
2. Understand what a clean certificate does not mean. NSW planning policy expressly contemplates councils answering "unknown" where they do not hold the information, and warns that unmapped land may still be subject to flood related development controls. A blank notation is evidence the council has not mapped the land. It is not evidence the land does not flood.
3. Check the state or council flood mapping portal. This varies more than any other step, so use the table below. Queensland buyers are best served: Brisbane City Council's FloodWise Property Report is free and address-level, giving flood levels in metres AHD and habitable floor requirements across four sources of flooding, being river, creek and waterway, storm tide, and overland flow. Overland flow is the one people forget, and the one that ruins garages.
4. Establish the property's height above the nearest watercourse. Flood risk is decided by centimetres of elevation. Geoscience Australia's ELVIS portal gives free access to national elevation data, including 1 metre, 2 metre and 5 metre digital elevation models. Compare the floor level to the benchmark the report actually applies to houses, which in Brisbane is the minimum habitable floor level, calculated as the 1% AEP level for the highest applicable flood source plus 0.5 metres of freeboard. (The 3.7 metres AHD Defined Flood Level at the Brisbane City gauge that gets quoted in general coverage applies only to non-residential uses.) A house 2 metres above that level is a different asset to its neighbour 300 millimetres below it, though both sit in the same mapped zone.
5. Ask the agent, in writing, whether the property has flooded. In writing matters, because it converts a conversation into a record. What that answer legally obliges them to tell you depends entirely on the state, which is the next section.
6. Get three insurance quotes on the actual address before you exchange. This is the highest-value ten minutes in the process, and almost nobody does it. The premium is the market's real price on the risk, computed off data you cannot otherwise reach. Quote the specific street address, not the suburb. Since June 2012 insurers have all worked to a single standard flood definition, but each one still decides whether to include flood cover as standard, make it an opt-out, make it an opt-in, or refuse it altogether. A refusal to quote is itself the answer.
7. Make the contract conditional where you can. Outside auction, ask your conveyancer about a clause making the contract subject to obtaining home and contents insurance, including flood cover, on acceptable terms within a set number of days, sitting alongside the finance condition. It is not standard and a vendor can refuse, but it turns an unquotable address from a lost deposit into a lawful exit.

Step 3 is the one that is hard to do from a laptop, because council mapping quality changes street by street. Buyers purchasing interstate often hand it to someone who already works the catchment, and GoMatch lists them by area.

How to tell if a house has flooded, at the inspection

Mapping and certificates miss unmapped overland flow, so read the building itself. Look for a horizontal tide line or staining on brickwork, fence palings or the underside of eaves; fresh gyprock or new skirting on the lower half of walls only; replaced flooring in one room; power points and switchboards mounted unusually high; silt, rust marks or a waterline in the subfloor, garage or under the stairs; swollen doors and rusted frames; a rendered or freshly painted lower course of brick on an otherwise unrenovated house; and new stormwater pits or a rebuilt retaining wall in the yard. Ask your building inspector to note flood indicators specifically, because a standard report is not required to.

Flood disclosure laws by state: what the seller or agent must tell you

Disclosure obligations are nowhere near uniform, and the gap between the best jurisdiction and the worst is wide enough to change what a house is worth.

Note the trap in the Queensland row. The Form 2 scheme is written up everywhere as the end of caveat emptor, and on flooding it changes nothing.

Free flood maps by state: where to check a property address

The council portals were funded under a program the Queensland Reconstruction Authority required to be completed by 30 June 2026, so check whether your council's portal is actually live, because coverage varies.

Three honest warnings. First, the insurer's rating is not ground truth either. CHOICE reported in October 2025 that the Insurance Council, in its submission to the parliamentary inquiry into the insurance industry's response to the 2022 floods, estimated around 675,000 Australian properties, or 4.4% of all properties, face a greater than 1% annual flood risk. CHOICE called the database a patchwork rather than a single source of truth, because many underlying council flood studies are out of date, and documented cases where a council assessed a property as having no significant flood risk while insurers priced it as high risk. Do both checks, and where they conflict, take the council evidence back to the insurer.

Second, be sceptical of anything sold to you as "the insurers' flood rating". Commercial flood reports are built from public and proprietary datasets of their own, not from the National Flood Information Database, which the Insurance Council licenses to insurers rather than to consumers. Such a report can still be useful, but it is not the number your insurer is pricing off.

Third, if you are buying in the north, do not assume the cyclone reinsurance pool covers you. It applies to cyclone-related flood damage only, and only within the Cyclone Event Period, which ends 48 hours after the cyclone ends. A house that floods in an ordinary March rain event sits outside it.

Flood risk and your home loan: when insurance blocks settlement

A certificate of currency naming the lender is commonly required before funds are released. No insurer, no settlement. Timing differs because risk passes at a different point under each state's standard contract: in Queensland, South Australia, Tasmania and the ACT cover is generally arranged from exchange, while in NSW and Victoria it is commonly arranged from settlement. Your contract governs, so confirm the point with your conveyancer rather than assuming the state default.

The Actuaries Institute found about 5% of mortgaged Australian households are in home insurance affordability stress, representing $57 billion of loan balances and 3% of all home loan assets. That is how an insurance problem quietly becomes a credit problem.

APRA has already modelled this by postcode. Its banking Climate Vulnerability Assessment, published in November 2022 and covering the five largest banks, found the most impacted 20% of postcodes accounted for around 75% of total modelled cumulative mortgage losses to 2050. Its March 2026 insurance assessment adds the scale: roughly 1 in 7 households are currently uninsured, projected to reach 1 in 4 by 2050, and 77% of severely flood-exposed homes carry no flood cover.

You are also buying the pool of future buyers who will be able to finance it. Get a mortgage broker to confirm lender appetite for the postcode before you commit, not after.

Not every flood zone is the same: floor height beats the mapped zone

A well-elevated house in a mapped catchment can be a completely sound purchase. That is why the Brisbane report gives you a floor level in metres AHD instead of a colour on a map. The colour is the catchment. The number is your house. Coastal south-east Queensland's 31% recovery is what that looks like in the data, and resilient, well-elevated stock may hold value better as the market learns to discriminate, the same logic behind climate-resilient property investment.

The mistake is not buying near water. Water is why so many of Australia's best neighbourhoods exist. The mistake is buying without pricing it, and then discovering the price at renewal.

Limits of this data

Aggregates are not your property. The UTS discount figures come from one floodplain, three suburbs and a sample of only 37 sales in the highest-risk zone, and may not travel to a different catchment. Cotality's coastal and inland split describes market averages, not your street.

Figures move, and several here have vintages that matter. The Actuaries Institute affordability numbers cover the year to March 2024, and APRA's banking postcode analysis is from November 2022. The council flood studies underpinning all public mapping are themselves of wildly varying age, which is the core of the CHOICE criticism.

None of this is financial, legal or insurance advice. Before you exchange, get a conveyancer to review the certificates for the actual property, and get real quotes on the actual address. Most of this workflow is free and you can run it yourself in an afternoon. For a straightforward purchase in a well-mapped Queensland suburb, there is little a professional adds to the flood question that FloodCheck and three quotes do not, which is the honest version of what a buyer's agent actually does. The case for paying one is narrower: unfamiliar catchments, thin council mapping, or a contract read under auction time pressure, and we set out where that fee earns itself in do I need a buyer's agent.

FAQ: flood risk and buying

How do I find out if a property has flooded before in Australia?

Start with the planning certificate from the council, then the state or council flood portal. Queensland's FloodCheck shows historic floodlines for 1893, 1974, 2010 and 2011, and Brisbane's FloodWise report is free and address-level. Then walk the house looking for tide lines, high-mounted power points and one room of replaced flooring, and ask the agent in writing.

Do sellers have to disclose flooding in Queensland?

No. The mandatory seller disclosure scheme under the Property Law Act 2023 commenced on 1 August 2025 and is widely described as ending caveat emptor, but the Queensland Government's own guidance expressly lists flooding history as something the seller is not required to include, alongside structural soundness. Queensland does have the country's best public flood mapping, so the burden of checking falls on you.

What does a 1 in 100 year flood zone mean?

It means land with a 1% chance of flooding in any given year, properly called the 1% Annual Exceedance Probability zone. It is not a once-per-century event. Over a 30-year mortgage there is roughly a 26% chance of at least one such flood, and about 55% over an 80-year building life. Floor height above the applicable flood level matters far more than the zone label.

Can you get a home loan on a flood-prone property?

Usually yes, but insurance is the gate. Lenders typically require a certificate of currency before releasing funds, so if no insurer will cover the address, settlement can fail. Banks model climate risk geographically now: APRA found the most impacted 20% of postcodes accounted for around 75% of modelled cumulative mortgage losses to 2050. Confirm lender appetite for the postcode early.

Where this leaves you

The asymmetry is real and it is not going away soon. Australian researchers have pointed out that this country is an international outlier, because the Netherlands, the United Kingdom and the United States all publish flood risk information to households. The Insurance Council is asking for a $30.15 billion Flood Defence Fund over ten years, including $10 billion for managed relocation and buybacks. Policy may eventually catch up. Your contract will not wait for it.

Watch the calendar too, because your cooling-off window is short, uneven and easily signed away.

In NSW that period can be waived outright by a section 66W certificate, and in Queensland it can be shortened or waived by agreement, so check what your own contract actually leaves you. There is no cooling-off period on any auction purchase anywhere in Australia, so at auction every one of these checks must be finished before you raise your hand, as we set out in the auction playbook. Council mapping is also thinnest exactly where regional buying is hottest.

If the quotes come back ordinary, you have bought certainty for the cost of an afternoon. If an insurer declines to quote at all, you have learned something the vendor may never have been obliged to tell you, while you could still walk away.

Sources

1. Song Shi, Mustapha Bangura and Sumita Ghosh, "Cognitive limits of perceived flood risk on residential property values". International Journal of Disaster Risk Reduction, vol. 114, 2024.
2. Insurance Council of Australia, "Flood" (Flood Defence Fund). Accessed 2 September 2026.
3. Queensland Government, "Seller disclosure scheme". Accessed 2 September 2026.
4. Australian Prudential Regulation Authority, "Climate Vulnerability Assessment Results". November 2022.
5. Australian Prudential Regulation Authority, "Mind the Gap: An Insurance Climate Vulnerability Assessment". 24 March 2026.
6. Actuaries Institute, "Home Insurance Affordability and Home Loans at Risk". 26 August 2024, data to March 2024.
7. Cotality, "Short memory of floods masks rising coastal home risks". 25 February 2026.
8. CHOICE, Andy Kollmorgen, "How accurate are the flood-risk ratings behind home insurance premium hikes?". 14 October 2025.