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For some developments you must consult one or both of :

• the Environment Agency
• the lead local flood authority (LLFA)

For other developments you must use the flood risk standing advice in this guide. This guide applies to the following application types:

• full
• outline
• reserved matters
• change of use
• prior approval for flood risk under certain permitted development rights
• permission in principle
• technical details consent

You must also consult the Environment Agency on a range of other issues. These are set out in Schedule 4 of the Development Management Procedure Order, 2015 (DMPO).

Other risk management authorities may also ask you to consult them. For example:

• the Internal Drainage Board (IDB) when development is in an internal drainage district (IDD) see the map of IDDs
• the water and sewerage company when sewer flooding may be an issue check to find the water and wastewater provider

Research the development site

• use the Environment Agency flood map to find if the development is - in flood zone 1, 2 or 3 - within 20 metres of a main river or a flood defence - in a water storage area
• find out whether the development is in an area with critical drainage problems - note these are currently only designated in Devon and Cornwall, contact the Environment Agency if you are unsure
• check your SFRA to find out if the development is - in flood zone 1 now but will be at risk of flooding from rivers or the sea during its lifetime - in flood zone 3b (functional floodplain) - at risk from sources of flooding other than rivers or sea
• establish the site area and check the development class
• find out the vulnerability classification
• use the following guidance to work out whether you need to consult or follow the standing advice

Check the development class

Major development involves one or more of the following:

• providing 10 or more dwellinghouses defined in article 2 of the DMPO or, where the number of dwellinghouses is not known, the site area is 0.5 hectares or more
• providing a building or buildings where the floor space to be created by the development will be 1,000 square metres or more
• development on a site of 1 hectare or more
• the winning and working of minerals or the use of land for mineral - working deposits
• waste development

A minor development is:

• development of an existing dwellinghouse, or development within the curtilage of a dwellinghouse, for any purpose incidental to the enjoyment of the dwellinghouse
• an extension to an existing building used for non-domestic purposes where the floor space created by the development does not exceed 250 square metres
• alterations to an existing building which do not increase the size of the building

Non-major development is any development not falling into the major or minor development classes.

Check if a flood risk assessment is needed and if one is provided

Before you validate the application, you should check if a flood risk assessment (FRA) is needed and if one is provided.

A FRA is required for all development:

• within flood zones 2, 3 or 3b
• within flood zone 1 with a site area of 1 hectare or more
• within areas with critical drainage problems
• within flood zone 1 where yourSFRAshows it will be at increased risk of flooding during its lifetime
• that increases thevulnerability classificationand may be subject to sources of flooding other than rivers or sea

Check if information on sustainable drainage systems is needed and if it is provided

Before you validate the application, you should check if a sustainable drainage strategy is needed and if one has been provided.

A sustainable drainage strategy is needed for all:

• 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 high risk of surface water flooding

The Sustainable Drainage System (SuDS) will need to provide benefits for:

• water quantity
• water quality
• biodiversity
• amenity

The sustainable drainage strategy will need to include all the information set out in what information on sustainable drainage needs to be submitted with a planning application? The strategy could be a separate document or part of theFRA, where relevant.

For major development, the SuDS will also need to provide multifunctional benefits, where possible. More information on multifunctional benefits can be found in what are sustainable drainage systems and why are they important?

Check to see if you (or theLLFA) have local guidance on SuDS with additional information requirements.

The sequential and exception tests

When the sequential test is needed

Asequential testis required for major and non-major development (check the development class section above) if any proposed building, access and escape route, land-raising or other vulnerable element will be:

• in flood zone 2 or 3
• in flood zone 1 and yourSFRAshows it will be at increased risk of flooding during its lifetime
• subject to sources of flooding other than rivers or sea

A development is not exempt from the sequential test just because a flood risk assessment shows the development can be made safe throughout its lifetime without increasing risk elsewhere.

See what the aim of the sequential approach is.

When development is exempt from the sequential test

A development is exempt from the sequential test if it is a:

• householder development like residential extensions, conservatories or loft conversions
• small non-domestic extensions with a footprint of less than 250 square metres
• change of use (except changes of use to a caravan,
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