The Government’s National Planning Practice Guidance (NPPG) on flood risk and coastal change was recently updated (17th September 2025) with revisions to paragraphs 23, 27 and 28, plus a new paragraph 27a.
These changes clarify how the sequential test and related considerations should be applied. In summary, the guidance continues to steer development away from high risk areas but adds detail on defining search areas, identifying alternative sites, and seeking to streamline the need for sequential tests at application stage. Below we outline each change and discuss the practical implications for the development sector.
Paragraph 23 – “What is the aim of the sequential approach?” (Changed to better align with the NPPF)
Paragraph 23 of the guidance reiterates the core sequential test approach. It confirms that a “sequential, risk based approach” must be followed to direct new development to areas of lowest flood risk. If low risk sites are unavailable, decision makers should compare “reasonably available” sites first in medium risk areas, then, only, if necessary, in high risk areas.
The guidance maintains that existing flood defences are initially ignored when comparing sites, since their long term performance (and climate change impacts) is uncertain. Only after identifying the lowest risk sites in each category should defences be considered to fine tune risk variation (for example, by assessing flood depths or hazard if defences might be exceeded). Following mixed legal judgements in previous years, this paragraph now reinforces the current National Planning Policy Framework (NPPF) stance that surface water flood risk, and other sources of flooding have equal importance alongside river and tidal flooding in sequential testing.
In sentiment, paragraph 23 is unchanged, as it still stresses climate change must be accounted for, and that site comparison ignores defences at first, however the emphasis that all sources of flooding must be considered equally is a key change.
In other words, the sequential test methodology itself is not altered, it remains the “most effective way of addressing flood risk” by avoiding high risk areas (as previously emphasised), but the specific process in running the test is updated to more closely align with the NPPF and case law.
Another positive change to the PPG, is that it no longer references Strategic Floor Risk Assessments (FRAs) as being the basis for Flood Zones used in a Sequential Test, it will now be the most up-to-date EA Flood Map for Planning which allows such mapping to be challenged and then used in a Sequential Test.
Paragraph 27 – How should the sequential test be applied to planning applications?
This paragraph now provides a direct reference to the NPPF, and to both the types of development that a Sequential Test should apply to and its exemptions, benefitting practitioners by provided more clarity.
Crucially, a proportionate approach to the application of NPPF paragraph 175 is newly introduced. This means that if a proposed development is shown to be ‘safe’ for its lifetime and not increase flooding elsewhere, then the Sequential Test need not be applied. This paragraph however only applies to surface water flood risk and planning applications, and not Local Plan allocations.
This will by extension streamline processes for such applications and allow for mitigation measures to be designed in to manage surface water flooding. Being able to account for local drainage systems and culverts, which surface water flood mapping in many instances does not, will avoid the need to ‘design around’ lots of areas of surface water flooding, which are often only shallow. Thereby allowing a more flexible framework for master planning. This clearly needs to be supported through carefully considered Sustainable Drainage Systems (SuDS) designs, earthworks/levels strategies and how residual flood risk might impact access/egress.
Paragraph 27a – “Defining the Area of Search” (New Paragraph)
The new paragraph 27a introduces new guidance on how to determine the area over which the sequential test is applied (the “area of search”). It explains that for individual planning applications, the search area depends on local circumstances: for instance, the catchment or functional area relevant to the proposed development. The catchment should be “appropriate to the nature and scale” of the proposal, for example, a school’s area of search might be its service area, while a housing site’s search doesn’t extend beyond the town or neighbouring villages.
The guidance urges a pragmatic approach: small extensions to an existing use may not require a wide search if splitting the site is impractical. Conversely, in locations where large parts of a town lie in Flood Zone 2 or 3 and development is needed to sustain the community, it acknowledges that alternatives outside those zones may be scarce.
For major infrastructure projects, paragraph 27a adds that the search may extend beyond the local authority boundary, reflecting regional or national catchments. It even suggests considering “splitting” a large development across multiple lower risk sites if those sites could collectively serve the same purpose.
Previously the NPPG did not explicitly define the extent of the search area for individual applications; applicants and authorities had to infer it. Now, paragraph 27a clarifies that the search area is not one size fits all but should be tailored to the proposal’s context. Planners and applicants must therefore agree a sensible search boundary (for example, a town or catchment), rather than arbitrarily wide or narrow areas. The emphasis on proportionality and local context is new.
Paragraph 28 – “’Reasonably Available’ Site Definition”
Paragraph 28 defines what counts as a “reasonably available” alternative site in the sequential test. It states that a site is reasonably available if
(1) its location is suitable for the type of development proposed
(2) it can meet the same development needs, and
(3) it has a reasonable prospect of delivery at the same time as the proposal.
Importantly, the guidance notes that alternative lower risk sites can include “two or more smaller sites” working together to provide the needed capacity. It also makes clear that these alternative sites do not have to be owned by the applicant – ownership is irrelevant to their availability.
This wording replaces and expands the previous definition of reasonably available sites with a clearer, testable definition. The paragraph emphasises suitability, simultaneous deliverability, and identical use as criteria. In practice, it tightens the test: developers must actively consider whether any suitable sites (including combinations of smaller plots) could be developed in tandem, even if they are not on the open market or in the applicant’s ownership.
Impact on Development Projects in Flood Risk Areas
Developers must continue to engage early to define an appropriate area of search with the LPA and rigorously document alternatives. The definition of reasonably available means a site must be both suitable for the same use and deliverable concurrently. Developers will need to provide clear evidence that they have considered all realistic lower risk options within the agreed search area. The guidance explicitly notes that arguments about a shortfall in five year land supply do not exempt developments from the sequential test.
Developers proceeding with applications outside of Local Plan promotion, may benefit from additional flexibility in sequential tests. The change in Paragraph 27, enables an evidence based approach for development proposed within areas of surface water flood risk to demonstrate it is ‘safe’ for its lifetime and will not increase flooding elsewhere, allowing the Sequential Test requirement to fall away. Our teams are primed to assist in justifying this approach, minimising delay and reviewing master plan improvement opportunities.
In preparing site specific FRAs, our Consultant team will now be aligning with the new wording, reinforcing our already advised pragmatic approach to Sequential Tests. Reports will benefit from the guidance, in explicitly defining the search area, discussing any potential alternative sites (even if off market), and demonstrating why none are viable in lower risk zones.
All those in the industry will ultimately benefit from the added clarity that these changes bring forward, which professionals have been calling for following continued case law emerging in recent years.
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