Brisbane FloodWise Property Report: how to read it

Brisbane City Council runs two free flood tools for addresses inside the Brisbane local government area: the Flood Awareness Map, a plain overview of how likely a property is to be affected by each type of flooding, and the FloodWise Property Report, a longer technical document with flood levels. Both are reached through the Flood Awareness Map. To check a property, search the address, read the flooding overview, then download the report if you want the numbers.

LayeredGeo is not part of Brisbane City Council or the Queensland Government. The Flood Awareness Map and FloodWise Property Report are free council tools and the right place to start for flood information on a Brisbane address.

How to get a FloodWise Property Report

1. Open the Flood Awareness Map using the link above and type an address, lot and plan, or suburb into the search bar.
2. Pick the matching result. The property is outlined in red, and a "Flooding Overview" panel summarises the flood types that can affect it and how likely each one is.
3. Click the "Technical FloodWise Property Report" button in that panel. The council says the download takes about 20 seconds.

There is another route if you are building: choose "I am in construction or development", then "I want a Technical FloodWise Property Report", enter the address or lot number and follow the prompt. There is no account and no payment step, and the tool only covers addresses inside the Brisbane local government area. Pull one for every property on your shortlist, not just the one you make an offer on.

How to read the flood types

The council describes four sources of flooding, and a property can be affected by one or a combination:

• River flooding: water rising out of the Brisbane River, which is what most people picture from 2011 and 2022.
• Creek or waterway flooding: water rising out of creeks and smaller waterways. This is common in suburbs well away from the river.
• Overland flow: stormwater running across the surface after heavy rain, usually along a low path between buildings or down a slope. It can affect a property with no river or creek nearby.
• Storm tide: sea water pushed up by a storm surge and high tide, relevant mainly near the bay and tidal reaches.

Overland flow is the one to watch. In the report it sits in the planning and development information rather than on the flood graph or the aerial map, so a property can look clear on the map and still carry an overland flow flag.

How to read the likelihood terms

The Flood Awareness Map describes each flood type as a high, medium, low or very low likelihood. The report is more technical and uses AEP, or annual exceedance probability, which is the chance of a flood of a given size happening in any one year. The report lists levels at 20%, 5%, 2%, 1% and 0.2% AEP where they apply. A 20% AEP flood is a regular event. A 0.2% AEP flood is rare. The 1% AEP level, roughly a one in 100 chance each year, is the one commonly used for development. A 1% flood is not a once in a century flood: it can happen two years running.

How to read the levels and heights

The graph and the technical section give flood levels as heights above sea level, which you compare with the ground. The report's sections include:

• Ground level analysis: the lowest and highest ground levels on the lot, an indicative existing floor level and the source of the highest flooding.
• Flood levels for different likelihoods: river, creek and storm tide levels at each AEP.
• Historic flood levels: how the January 2011 and February 2022 floods compare, where data exists.
• Minimum habitable floor level: the level habitable rooms need to sit at under City Plan. For a dwelling, the council's explainer describes it as generally the 1% AEP level of the highest flood type plus 0.5 metres.
• Flood planning areas and overlays: which City Plan flood overlays apply.
• Property development flags: special considerations such as an overland flow path.

To use the numbers, compare the flood level with the ground. If the 1% level is above the lowest ground level, water is modelled to reach part of the lot. The lowest and highest ground levels cover the whole lot and may not be the ground at the house, so subtracting them does not give the depth there. For that you need the ground level at the house site itself, such as from a survey. If the flood level is above it, the difference is roughly the depth there; if it is level with or below it, the house site is not modelled as flooded at that likelihood. Then compare the existing floor level with the minimum habitable floor level. A house sitting below it was likely built before today's rules, and a renovation or rebuild may need to meet them.

What it does not tell you

• No levels does not mean no risk. The report uses only flood information the council has adopted and says it may not be complete. A habitable floor level may be missing for large lots or properties in an overland flow path, and overland flow can still apply.
• It is not a guarantee. The Flood Awareness Map is a general tool. It is not a real-time warning and does not show how deep or fast the water runs. Flood mapping reflects models, not your street on the day.
• It is not professional advice. The council recommends a Registered Professional Engineer of Queensland for advice, and says you can dispute flood information by writing to the Flood Information Officer with supporting evidence such as certified survey levels.
• It is not a planning certificate or a title search. Easements and covenants come from the title, and the council's own property searches are separate documents.
• It says little about ground conditions. Soil reactivity, fill and groundwater affect footings and are not part of a flood report.

Comparing suburbs before you shortlist

The report works one address at a time. To compare how much of each suburb is flood-affected before you shortlist, see our Brisbane flood map by suburb. Then run the council report on the specific addresses you like, because the flood level can change a lot between two streets in the same suburb.

Putting the flood and planning layers in one PDF

The council tools are the official source, so start there. If you want flood alongside everything else, LayeredGeo's Property Report puts zoning, flood, bushfire, heritage, vegetation and environmental overlays for an address into one PDF with a map and a plain-English note for each, alongside contours, registered easements and the water, sewer and stormwater mains the utilities publish. The map preview is free and the PDF is $9. Pop in your address or check out a sample report.

If you are building, a separate geotechnical desktop study covers the geology, soils, indicative soil reactivity range and groundwater for the address. It does not replace a site investigation, which is what decides the site classification.

Common questions

Is the FloodWise Property Report free? Yes. You download it from the Flood Awareness Map in about 20 seconds, with no account and no payment step. It only covers addresses inside the Brisbane local government area.

What is the difference between the Flood Awareness Map and the FloodWise Property Report? The Flood Awareness Map is a general tool showing how likely a property is to be affected by river, creek, overland flow and storm tide flooding. The FloodWise Property Report is a technical document with flood levels at different likelihoods, historic levels and the minimum habitable floor level.

What does 1% AEP mean on a Brisbane flood report? It is a flood with a 1% chance of happening in any one year. It is the level commonly used for development, and for a dwelling the minimum habitable floor level is generally that level plus 0.5 metres.

Does a report with no flood levels mean the property cannot flood? No. The council says flooding can still be a risk where no levels are shown, because overland flow may apply and the report only uses information the council has adopted.

LayeredGeo's Property Report pulls together public planning and site data for property due diligence across Queensland, New South Wales, Victoria, South Australia, the ACT and Tasmania, so you can understand a place before you commit.

About this article. Published by LayeredGeo and written from the published research cited in the Sources section above. It is general information about how property and ground conditions are assessed in Australia, not engineering, planning, legal or financial advice, and it is not specific to any property. Check anything that matters against the source dataset or a suitably qualified professional before you rely on it. If you spot something wrong, tell us at hello@layeredgeo.com.au and we will fix it.

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