Homeowners’ guide to flood risk assessments

Publish Date : 28 Nov 2023
38 421792

Flood risk assessments are a free service provided by the Tāmaki Makaurau Recovery Office to help homeowners and the council understand flooding risks. This handy guide (PDF 1.39MB) gives you a preview of what to expect.

Flood risk assessments help us to understand if flooding from future severe storms creates an intolerable risk to life. We also assess whether feasible changes can be made to your property or in your community to reduce the risk. We call these changes ‘mitigations’.

“At its heart, this is about keeping you and your whānau safe when we have extreme weather events in future. Some homes and neighbourhoods may be vulnerable to a future flooding risk that is unacceptably high, and we are doing what we can to keep people out of harm’s way or reduce risk. When your category is confirmed, we'll provide mitigations and information that determines the risk level to help you understand how we got there,” says Mat Tucker, Group Recovery Manager.

Complete this online form if you are unsure or concerned about your flooding risk after the storm events earlier this year and would like an assessment to confirm the risk to your home.

Frequently asked questions

Do I need a flood risk assessment?

In some cases, it will be obvious that a risk assessment is needed – for example if your home flooded during the storm events this year. If you have concerns about flooding at your property we recommend you complete the online form to get a free assessment.

What information do you collect in the desktop assessments?

We collect information from your completed online form, property files, council records, photographs, flood modelling information, flood hazard maps, infrastructure servicing records, rainfall data, and calculations for water flowrates, velocities and depths.

What information do you collect through site visits?

We talk with the property owner or occupier to confirm that the information we have is accurate. We may also investigate options to reduce flooding risk to the property or the neighbourhood.  

What are the criteria for assessing risk to life from flooding?

The criteria considered are the frequency of the flooding event, the amount of water flowing (flowrate) as well as the depth or speed of the water. 

The frequency of the event we call the Annual Exceedance Probability (AEP). That is the probability of the event being equalled to or exceeded in any year. Council’s standard for flood hazard assessment is to consider the flooding event that has one chance in 100 of being equalled or exceeded in any year. This compares for example to the New Zealand Building Code (NZBC) which considers the event that has one chance in 50 of being equalled or exceeded in any year, that is, the council considers an event bigger than required in the NZBC.

Auckland Council will assign a Flood Hazard Rating which represents the threat to life to people exposed to a flood hazard inside or outside the home.  

Is categorisation information included on the LIM or property file?

Correspondence with homeowners about categorisation is included on property files. To ensure transparency, Auckland Council will disclose Category 2 and Category 3 information on LIMs for storm-damaged properties. More information in the Our Auckland story Auckland Council provides LIM transparency for property categorisation.

I also want a landslide risk assessment how do I make this happen and what can I expect?

You will find more information on the Our Auckland story Homeowners guide to landslide assessments.

Where can I get more information on flooding in Auckland?

Read this Our Auckland story Auckland Council makes it easier to access flood data.

Back to News