Flood risk assessments: applying for planning permission
Find out when you need to do a flood risk assessment as part of your planning application, how to complete one and how it is processed.
Applies to England
This guidance is for planning applicants.
Local planning authorities (LPAs) should use the National flood risk standing advice for local planning authorities when reviewing flood risk assessments.
As a planning applicant, you may need to carry out a flood risk assessment (FRA) for your proposed development site.
You will usually need to pay a flood risk specialist to carry out a FRA for you. An exception to this may be if it is for a simple, low risk development, for example, a house extension. In this case you may be able to do it yourself. If you are not sure, contact the Environment Agency for advice.
Your local planning authority (LPA) may refuse your application if you do not include a FRA or if it is not satisfactory.
When you need a flood risk assessment
You need to do a FRA for all development (including minor development and changes of use) proposed:
- in flood zones 2, 3 or 3b
- within flood zone 1 with a site area of 1 hectare or more
- in areas with critical drainage problems
- within flood zone 1 where the LPA’s strategic flood risk assessment (SFRA) shows it will be at increased risk of flooding during its lifetime
- that increases the vulnerability classification and may be subject to sources of flooding other than rivers or sea
When you need a sustainable drainage strategy and what to include
You need to include a sustainable drainage strategy if your application is for:
- major development with surface water drainage
- development with surface water drainage in an area at risk of flooding such as flood zones 2 or 3, or at risk of surface water flooding
You should include all the information set out in:
- section 6 of the site-specific flood risk assessment checklist
- What information on sustainable drainage needs to be submitted with a planning application
Your sustainable drainage strategy can be a separate document or be part of a FRA. Check to see if the LPA or lead local flood authority (LLFA) have local policies or guidance with additional requirements.
Research the development site
To access the right flood risk advice for your development, you need to complete all the following steps:
- use the Environment Agency Flood Map for Planning to find if the development is in flood zone 1, 2 or 3
- check the LPA’s SFRA to identify if the site is in flood zone 3b (functional floodplain).
- find out the vulnerability classification - if you are unsure discuss this with your LPA and make it clear in your FRA
- check Table 2 of the Planning Practice Guidance to find out if the proposed vulnerability classification is incompatible with the flood zone
- check the LPA’s SFRA to identify if the site is in flood zone 1 now but will be at risk of flooding from rivers or the sea during its lifetime
- check the LPA’s SFRA to identify if the site is at risk from any other source of flooding or it will be during its lifetime
- refer to Check the long term flood risk for an area in England to identify if your site is at risk of flooding from surface water, groundwater (where data is available) or reservoirs
- check if the site is in an area with critical drainage problems – these are currently only designated in Devon and Cornwall and the Environment Agency has provided local standing advice for these areas
- establish the site area (in hectares) and whether the development is major development
- check if your development is a minor extension
A minor extension is a household or non-domestic extension with a floor space of no more than 250 square metres.
In some cases, SFRAs may not hold suitable information for your site on future flood risk or functional floodplain. In such cases, your FRA will need to provide suitable information.
Note that Check the long term flood risk for an area in England also shows the risk of flooding from rivers and sea. However, this information is different to the flood zones shown on the flood map for planning. This means you should not use it for development planning.
Access the right advice
Follow the Environment Agency’s advice for minor extensions if you are doing a FRA for a minor extension in flood zone 2, 3 or 3b.
Follow the Environment Agency’s standing advice for vulnerable developments if you are doing a FRA for a development (including change of use) in flood zone 2 classed as:
- ‘more vulnerable’ - except for landfill or waste facility sites, caravan or camping sites
- ‘less vulnerable’ - except for waste treatment, mineral processing, and water and sewage treatment
- ‘water compatible’ - including essential accommodation within a water compatible development
You should follow standing advice for vulnerable developments for change of use development in flood zone 3 where the vulnerability classification will:
- be ‘water compatible’
- remain unchanged as ‘less vulnerable’
Also follow local flood risk standing advice for development (including change of use) if your site is in an area with critical drainage problems – these are currently only designated in Devon and Cornwall. Contact the LPA for a copy of the local standing advice.
For all other development types requiring a FRA in flood zones 1, 2, 3 or 3b, you need to follow the advice in Flood risk assessment: flood zones 1, 2, 3 and 3b
If your site is in flood zone 1 but your LPA’s SFRA shows it will be at increased risk of flooding from rivers or the sea during the development lifetime, you should:
- make sure a FRA is done
- apply this guidance as if the site were in flood zone 2
Get information about flood risk from rivers and the sea to help you to complete a FRA
The Environment Agency has information which will help you complete your flood risk assessment.
This includes information on:
- flood risk from rivers and the sea and about flood risk management structures and features
- how climate change will affect flood risk from rivers and the sea in future
- residual flood risk to help you assess the consequences of flood defences being breached or overtopped
This information will help you calculate the estimated flood level for your site in the design flood and assess residual flood risks. Please note that the design flood must include an appropriate allowance for climate change.
These products or packages of information are available from the Environment Agency’s Flood Map for Planning service:
Product 1
This product is a copy of the flood map which shows:
- flood zones 1, 2 and 3
- defences
- statutory main river designations
- water storage areas
Product 3
This product has been discontinued. Relevant information is now available through other products.
Product 4
This product is a detailed FRA map. It shows:
- detailed flood data
- flood defence locations and attributes
- data on past flood events
- modelled flood levels and extents
- flood defence breach hazard information, if available
The models show the model extents and modelled flood levels and flows at one or more specific points. This could either be within the river channel or, if available, in the floodplain.
Product 5
This product is a report which includes flood modelling and hydrology reports.
Product 6
This product is the model output data and all the reports in product 5.
Product 7
This product is the Model Input Data, and all the reports in product 5. This represents the best available modelled data we have for the area. You will need to assess any model to make sure it is suitable for your FRA.
Product 8
Flood defence breach hazard information. This information will be included in Product 4 where it is available.
Choose the correct product
For all development you should request product 1 and product 4.
If your FRA will use detailed hydraulic modelling held by the Environment Agency, you are also likely to need products 5, 6 and 7. Refer to Using modelling for flood risk assessments for guidance on when to use modelling and the expected standards.
How to get or order the products
For all the products you need to use the Flood Map for Planning. Find the correct area by entering the postcode or location of the development site. Then draw the boundary of your site to get accurate flood risk information for your site.
For product 1, which is a copy of the flood map for planning for your development site, you can download a copy of the map.
For product 4 - input your name and email address on the page for your development site and submit it. The local Environment Agency team will send product 4 to you for that location.
For products 5, 6 and 7, you need to find the contact details for the local Environment Agency office and send a request to them. You can find these details in the flood map for planning on the page of your chosen development site.
Get information about other sources of flood risk to help you complete a flood risk assessment
You need to consider all sources of flood risk in your FRA. You can get information on surface water, groundwater (where available) and reservoir flooding by referring to Check the long term flood risk for an area in England. You may be able to get other information on flood risk, by contacting the:
- LLFA
- LPA for information from its SFRA
- water and sewerage company
- internal drainage board if you are in an internal drainage district
Contact the Environment Agency
If you would like more detailed, site-specific advice on flood risk, such as a review of your draft FRA, visit How to request Environment Agency advice.
Last updated 24 May 2024 + show all updates
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Amended title, removed discontinued products, added detail on how to research the development site, added links, updated and improved clarity of other sections.
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Changed URL "Find out what flood zone you're in" to the new Flood Map for Planning digital service
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Information about charges for products removed.
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Clarified flood risk product 8 should be used in an area behind raised flood defences in zone 3.
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Flood risk product information added.
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First published.