1. New versions of the Flood Zones

Created: 12 March 2025 Updated: 25 March 2025

Why the Environment Agency produces the Flood Zones

The Environment Agency has the delegated responsibility for producing Flood Zones in line with government guidance. Table 1 of the Planning Practice Guidance defines the annual probability that is used for producing Flood Zones. The Flood Zones show the extent of land at present day risk of flooding from rivers and the sea, ignoring the benefits of flood defences. The Flood Zones may also identify locations where flood risk extents could be greater if just some existing flood defences are removed, rather than all of them.

Local Planning Authorities (LPAs) use the Flood Zones to determine if they must consult the Environment Agency on planning applications. They are also used to determine whether development is subject to the exception test. The Flood Zones are one of several flood risk datasets used to determine the need for planning applications to be supported by a Flood Risk Assessment (FRA) and subject to the sequential test.

The Flood Zones ignore the potential effects of climate change on future flood risk.

LPAs are responsible for producing maps showing the extent of functional floodplain (Flood Zone 3b) as part of Strategic Flood Risk Assessment(s). The Flood Map for Planning does not identify functional floodplain.

How the Flood Zones are produced by the Environment Agency

From 25 March 2025, the Flood Zones are produced as part of the new National Flood Risk Assessment (NaFRA2).  This uses new national modelling alongside local models. The updated Flood Zones will combine several datasets to create a picture of flood risk, including:

• Undefended – flood defences are removed or de-activated

• Defended – existing flood defences are present and operational

• Recorded Flood Outlines – from past floods

• Other suitable data from third parties.

In some locations where the existing datasets are not of the required quality and where new flood risk models are expected to be available in the near future, we will ‘retain’ the Flood Zones from older datasets temporarily until these new models can be incorporated.

We have also retained the Flood Zones in some locations where we have previously received suitable data from third parties.

The data used in any given location is considered the best available information we hold at that time. We will update the Flood Zones when new, better information is available and where it meets the required standards.

How the Flood Zones have changed as part of NaFRA2

We have updated our flood risk information using a new process. This has been developed for our new national flood risk assessment. The process combines new and existing data to improve our national flood risk maps.

Local modelling of flood risk often captures important local features better than national modelling.

The new national model is a significant improvement on our existing national modelling. We will use outputs from this national model in areas where we do not have high-quality local modelling.

The new process has resulted in a range of improvements to the Flood Zones and our national flood risk mapping, including:

• Improved geographical coverage

• Improved model methodologies and outputs at a higher resolution

• Supporting information available alongside Flood Zones on the Flood Map for Planning, including information accounting for the possible effects of climate change.

Flood Zones 2 and 3 will no longer overlap, with clear attribution between the Flood Zones. This is different to how the data is currently displayed, where Flood Zone 2 includes areas that are in Flood Zone 3.

Our analysis indicates that at the national scale there is no significant change to the overall size of Flood Zones. However, where changes occur that coincide with proposed development, it will be necessary to ensure that the best available information is used to inform decisions.

Where to find further information

You can find out more about our new national risk information for flooding and coastal erosion by visiting this web page: Updates to national flood and coastal erosion risk information - GOV.UK (www.gov.uk) and this related DSP announcement: Defra Data Services Platform.

You can find further information on the Flood Zones and other national flood and coastal erosion risk data:

• LPAs and lead local flood authorities should access this Sharepoint site for briefing materials include a webinar recording, a detailed Q&A document, guidance on transitional arrangements, a demo of the new Flood Map for Planning, a diagram explaining the suitability of our new datasets for development planning purposes and various materials to help local authorities brief developers locally. Users will need to register the first time this site is accessed.

• Defra Data Services Platform product descriptions for the new datasets. These will be provided for each layer available through the service

• Risk Management Authorities can subscribe to updates about our new flood and coastal risk information

• Developers and FRA consultants can find briefing materials and guidance on New national flood and coastal erosion risk information on the Town and Country Planning Association’s website.