Section-by-section outline for a flood sequential test

A sequential test stands or falls on two things: the area of search you agreed with the authority, and the evidence that each discarded alternative was not reasonably available. Everything else in a sequential test flood submission is presentation. Get those two right and a short document will pass. Get them wrong and forty pages of mapping will not save it, because the officer has to be able to defend the conclusion in a committee report or at appeal.

The structure below follows the order an officer reads in, which is rarely the order the work was done in.

Agreeing the area of search

Open with the search area and say who agreed it. The Planning Practice Guidance on flood risk and coastal change expects the area of search to reflect the nature of the development and the catchment of the need it serves, and it expects that scope to be settled with the local planning authority rather than asserted by the applicant.

State it in three lines: the geographic extent, the reason that extent matches the development, and the date and route of the agreement with the authority. A pre-application email confirming the search area is worth more than any amount of later argument.

The extent follows the function. A local convenience store serves a walk-in catchment, so a ward or settlement boundary is defensible. A district-wide leisure use or a care home with a borough-wide referral pattern cannot sensibly be searched at street level. A site-specific allocation in the adopted plan narrows the question further, and where the plan has already applied the test at allocation stage, say so and cite the plan document and policy number.

Do not quietly shrink the search area to the applicant's land holdings. That is the single commonest reason a test is rejected.

Setting the site selection criteria

The criteria section converts the development into a filter. Each criterion needs a number or a defined parameter, and each needs a reason tied to the scheme rather than to the applicant.

• Minimum developable area, with the floorspace and parking that figure derives from.
• Access requirements, for example frontage to a classified road or a servicing bay of a stated length.
• Planning policy status, such as within a defined centre or within a settlement boundary.
• Any operational requirement that genuinely constrains location, such as proximity to an existing depot or a clinical catchment.

Keep the list short. Five criteria that each exclude sites for a stated reason beat twelve that overlap, because every criterion is a line an objector can attack as reverse-engineered to leave only your site standing.

Write the criteria before you run the search, and say in the document that you did. Where a criterion was relaxed during the search, record the relaxation and what it added to the long list.

Listing and screening the alternative sites

The long list comes from identifiable sources, and naming them is part of the evidence. Typically that is the authority's brownfield land register and strategic housing or employment land availability assessment, current allocations and saved allocations in the adopted plan, sites with extant permission that remain undeveloped, and sites openly marketed at the time of the search.

Present the long list as a table with one row per site and a consistent set of columns: reference, address, approximate area, flood zone from the Flood Map for Planning, the criterion it fails, and the source of that conclusion.

Since the December 2023 Framework the test has to consider all sources of flood risk, not only rivers and the sea. A site in Flood Zone 1 that sits in a mapped surface water flow path or a critical drainage area is not automatically a better alternative, and a test that treats zone colour as the only variable looks dated. Check the surface water mapping and the authority's own critical drainage information for each site you carry forward.

Recording reasonable availability

This is where most tests are thin. Availability is a judgement about whether the site could realistically be used for the proposed development, and it needs a dated source for each site, not an assertion.

Acceptable evidence includes a marketing particular with its date, a written response from the landowner or their agent, a register entry showing the site as developed or allocated for another use, a recent permission being implemented, or a site visit photograph showing the land in active use. Record who provided it and when.

Where a site is physically capable but is not for sale, say exactly that and keep the correspondence. An unwilling owner is a legitimate reason for unavailability where it is evidenced. It is not a legitimate reason where the only evidence is that nobody asked.

Date everything. A sequential test prepared on a two-year-old search is a liability, and the first thing a careful officer does is check whether anything on the discarded list has changed hands.

Applying the test site by site

For each site carried through the screen, set out a short paragraph in a consistent order: flood risk position, suitability against the criteria, availability, and the conclusion. Two to four sentences each is enough. Resist the urge to write a mini appraisal.

The comparison must be between the application site and the alternative on flood risk terms first. A site in Zone 1 beats a site in Zone 3a unless it fails on suitability or availability, and saying the Zone 1 site is less commercially attractive is not a flood risk answer.

One honest point worth making in the document: where every alternative sits in the same zone as the application site, the test is quick and should read that way. Padding a straightforward outcome makes it look defensive.

Wording the conclusion

The conclusion is three sentences and no more. It states the search area, states that no reasonably available site at lower flood risk exists that could accommodate the development, and states whether the exception test is therefore engaged.

Avoid conclusions that assert the test is passed as a matter of planning balance. The sequential test is a threshold question about alternatives, and the balancing happens elsewhere. A conclusion that drifts into benefits reads as an admission that the alternatives evidence is weak.

Where the test is not passed, say so and advise the client. A test written to a predetermined answer is worse than no test, because it gives the authority a documented reason for refusal in the applicant's own words.

Where the exception test follows, and why tests fail

If the sequential test cannot be passed and the proposal still comes forward, the exception test applies in the circumstances the Framework sets out. It asks whether the development would provide wider sustainability benefits to the community that outweigh the flood risk, and whether it will be safe for its lifetime without increasing flood risk elsewhere. The second limb is answered by the site-specific Flood Risk Assessment, including finished floor levels, safe access and egress, and the climate change allowances current at the time of submission.

The failures that recur are consistent. A search area drawn around the applicant's ownership. Criteria written after the search. Availability asserted without a date or a source. Only fluvial risk considered. No reference to the authority's own evidence base. A conclusion that argues merit rather than alternatives.

Treat the test as a standalone document even when it is short, so the officer can lift it into the report. A Sequential Test (Flood) draft and, where it follows, an Exception Test (Flood) draft can be structured in minutes and then populated with the dated search evidence only you can gather. Where a variation to an existing permission reopens flood matters, the document list in our guide to section 73 application documents shows what else usually travels with it.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.