Flood Risk Assessment (FRA)

A flood risk assessment (FRA) should accompany all development proposals in Flood Zones 2, 3a and 3b. In Flood Zone 1 an FRA is also required for some sites, including sites of one hectare or more, land with critical drainage problems, and land identified by the Strategic Flood Risk Assessment or the Flood Map for Planning as being at risk from any source now or in the future.

You can check the Environment Agency’s Flood Map for Planning, but you should also check the local authority’s Strategic Flood Risk Assessment because the mapped Flood Zones are not the whole flood-risk picture.

You will need a Flood Risk Assessment in the following scenarios:

• All development proposals in Flood Zones 2, 3a and 3b
• Development in Flood Zone 1 on a site of one hectare or more
• Development in Flood Zone 1 on land identified by the Environment Agency as having critical drainage problems
• Development in Flood Zone 1 where the Strategic Flood Risk Assessment or Flood Map for Planning identifies flood risk from any source, now or in the future

For anything beyond the simplest assessment, it is sensible to use a suitably qualified flood-risk professional. Their cost will depend on the site and the work needed. Council application charges are separate; see our planning application fees guide.

When a flood risk assessment needs the Sequential or Exception Test

The Sequential Test asks whether a reasonably available site with a lower risk of flooding could accommodate the development instead. Under the August 2026 NPPF it applies to areas known to be at risk now or in the future from any source of flooding, although there are specific exceptions for some allocated sites, some sites shown by an FRA to keep vulnerable elements out of the risk area, householder development, small non-residential extensions and most changes of use.

Policy F5 adds an important limit to the search geography: the area to which the Sequential Test is applied should not be greater than the anticipated catchment of the development in terms of its likely occupiers or users. That does not create one fixed search area for every proposal, but it does mean the NPPF no longer supports treating the whole local authority area as the automatic answer.

There is also a specific route where a site would be at risk from surface water flooding only. The Sequential Test is not required where the FRA clearly demonstrates that layout, design and mitigation will keep occupiers and users safe for the lifetime of the development without increasing flood risk elsewhere, in accordance with policy F7.

The Exception Test is needed in the combinations identified by Annex F, table 3 of the August 2026 NPPF, including highly vulnerable development in Flood Zone 2, more vulnerable development in Flood Zone 3a, and essential infrastructure in Zones 3a and 3b. Where it applies, the proposal must provide wider sustainability benefits that outweigh the flood risk, be safe for its anticipated lifetime, and not increase flood risk elsewhere, reducing overall risk where possible.

What if the Sequential Test is failed?

A failed Sequential Test is serious, but it is not an automatic statutory veto on planning permission. That distinction was considered in North Somerset District Council v Secretary of State for Housing, Communities and Local Government & Persimmon Homes Severn Valley [2026] EWHC 1430 (Admin).

In that case the Inspector found that the development had failed the Sequential Test. He did not then purport to pass the formal Exception Test. He nevertheless considered two matters which also feature within that test: the wider sustainability benefits of the scheme and whether the development could remain safe for its lifetime. The High Court held that he was entitled to do so as part of the overall planning balance.

The practical point is that failing the Sequential Test remains a substantial conflict with flood-risk policy and must be given proper weight. But matters such as lifetime safety, residual flood risk and the wider benefits of the proposal do not disappear from the decision simply because the Sequential Test has been failed. They remain capable of being material considerations.

Do not describe this as ‘passing the Exception Test despite failing the Sequential Test’. That was not what the court held. The distinction is between formally satisfying the policy tests and separately considering the underlying planning matters in the balance.

What to include in a flood risk assessment

• Your site address
• A description of your development
• An assessment of the flood risk from all sources of flooding for your development, plus an allowance for climate change
• The estimated flood level for your development
• Details of your flood resistance and resilience plans
• Plans and drawings showing the development
• Management of surface water and evacuation procedures, if applicable
• Emergency escape plans for any parts of a building that are below the estimated flood level
• Average ground level of your building
• Finished floor levels: Environment Agency standing advice normally recommends at least 600mm above whichever is higher of the average site ground level, the adjacent road level or the estimated river or sea flood level; 300mm may be appropriate where there is a high level of certainty about the estimated flood level
• Extra flood resistance and resilience measures, as applicable
• Sequential and Exception Tests, as required

If in any doubt, contact a professional to compile the Flood Risk Assessment on your behalf.

Conservation, Heritage & Protected Sites

Flood Risk Assessment Page Updated: 27th August 2026