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Flood risk assessments

A flood risk assessment – which is commonly referred to as an FRA is a technical report that must be provided as part of some planning applications.

Aim of a flood risk assessment

The aim of a flood risk assessment is to:

  1. determine the risk of flooding posed to a development and the impact that this may have elsewhere.
  2. to define the measures that will be used as part of the development to reduce and manage the risk of flooding. Both to the development and elsewhere.

When is a Flood Risk Assessments (FRA) required?

A  flood risk assessment 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 your LPA’s (Local Planning Authority) SFRA (Strategic Flood Risk Assessment) shows it will be at risk of flooding from rivers or the sea in future
  • that increases the vulnerability classification and is in flood zone 1 where your LPA’s SFRA shows it is at risk from other sources of flooding

Detailed information on when a flood risk assessment is required is available at:

For advice on minor extensions please visit: Advice for minor extensions – GOV.UK.

What information will I need to provide? 

An FRA must:

  1. Access the risk of flooding of a development site from all flood sources:
    1. Main Rivers – Fluvial
    2. Ordinary Watercourses – Fluvial
    3. Surface Water – Pluvial
    4. Sewers – Pluvial
    5. Ground Water
    6. Artificial Sources – such as reservoirs and canals

See our dedicated webpage on the Types of flood risk for more detailed descriptions.

  1. Evaluate the impact that the proposed development will have on flood risk at the site and elsewhere
  2. the risk of flooding from all sources. Both to the development and elsewhere.

Defines the measures – such as flood protection and flood resilience - that will be used as part of the proposed development to reduce and manage

  1. Assess the flood risk from all sources of flooding
  2. Evaluate the impact of the proposed development on flood risk and;
  3. Define how the flood risk from all sources will be managed and reduced (including the appropriate peak river flow and peak rainfall intensity climate change allowances). And as part of this, you must define the extra flood resistance and resilience measures that will be used to achieve this.

The peak river flow and peak rainfall intensity climate change allowances are calculated using the developments; flood risk vulnerability classification and proposed lifetime.

See: Site-specific flood risk assessment: Checklist.

Sequential and exception tests

As part of any flood risk assessment, it is expected that a sequential test is completed, and where appropriate an exception test is also completed. This ensures that a risk based approach is taken so that development is located in areas at lowest risk to flooding – taking into account the effects of climate change and considering all sources of flooding. See our page on Sequential and exception tests.

Drainage - surface water and foul

For all major developments, it must also comply with the non-statutory technical standards for sustainable drainage systems. The description of major development is defined in: The Town and Country Planning (Development Management Procedure) (England) Order 2010.

A connection to the public sewerage network is the preferred method of foul drainage. For developments falling within the definition of a major development the Environment Agency will advise the council. For development that does not fall with the definition of a major development, please read the guidance note and then submit a completed form with your planning application - see below:

Ordinary watercourses

Ordinary watercourses must also be considered as part of any FRA and detailed information is available on Ordinary watercourse flood extents and can also be viewed on our flood risk map section.

Emergency flood planning

Emergency flood planning must be considered as part of any planning application requiring an FRA and detailed information is available on: Emergency flood planning.

Sustainable Drainage Systems

Sustainable Drainage Systems (SuDS) are surface water management systems, which mimic natural drainage by providing collection, storage and treatment of surface water. As well as providing numerous benefits such as flood risk management, climate change adaptation and biodiversity and amenity improvements.

SuDS must be considered as part of any flood risk assessment for the purposes of flood risk management and reduction. They must also be considered as part of any development’s drainage strategy. See our dedicated webpage: Sustainable Drainage Systems (SuDS).

Flood risk studies

Visit our dedicated webpage: Flood risk studies.

Pre-application advice

We provide pre-application advice, which can help determine whether a planning application is needed and if so, what supporting information and reports will be required. See our Apply for pre-application advice section. Statutory consultees are consulted as part of this service with exception to the Environment Agency. As the Environment Agency have their own pre-application process and you will need to complete their Pre-application enquiry form. See the Pre-application guidance note: East Midlands PDF below for further details.

Where pre-application discussions with the council and the Environment Agency do not take place, planning applications can be refused without negotiation.

Paving your front garden

If you want to pave your front garden, you need to consider surface water runoff. Details of the rules are available on the: Planning permission - Paving your front garden - Planning Portal.

You may also need a dropped kerb. Further details are available on our Apply for a dropped kerb page.

In some cases, particularly if the access is to a classified road, planning permission may be necessary. Further information is available on our Do I need planning permission? page.