PPG flood risk: what the September 2025 Sequential Test update changed

The PPG flood risk guidance changed on 17th September 2025, and the four paragraphs it rewrote decide how a Sequential Test gets scoped and evidenced today. The sequential approach now reads across every source of flooding, surface water included. A flood risk assessment can remove the test, but only for surface water and only on a planning application. The area of search should be proportionate to the development. And an alternative site does not have to be one you own.

Paragraphs 23, 27, 27a and 28 of Flood Risk and Coastal Change all still carry a revision date of 17th September 2025. Checked against the live guidance on 30 July 2026, nothing further has changed.

The test itself is unchanged in principle. What changed is the evidence you have to file, the ground you have to search, and the one narrow route out of it.

What changed in the PPG on 17th September 2025

Three paragraphs of the Flood Risk and Coastal Change guidance were revised and one was added: 23 on the aim of the sequential approach, 27 on applying the test to planning applications, 28 on reasonably available sites, and a wholly new 27a on the area of search. No Framework paragraph changed alongside them, so this is guidance catching up with the December 2024 NPPF rather than a change of policy. The paragraphs they cross-refer to are in section 14 of the Framework.

Does your site still need a Sequential Test?

Most sites in an area at risk of flooding from any source still do. Paragraph 27 confirms the test applies to major and non-major development under NPPF paragraphs 173 and 174, and points to paragraphs 175, 176 and 180 for the exemptions. Four gates decide it, worked through in order: whether any part of the site is in an area at risk now or in future from any form of flooding, counting rivers, sea, surface water, groundwater, reservoirs, sewers and canals; whether it is minor development or a change of use, which paragraph 176 exempts; whether it is an allocated site already sequentially tested at plan-making stage, which paragraph 180 covers; and whether the risk is surface water only with a flood risk assessment that proves lifetime safety, which is the paragraph 27 route the September 2025 update created.

Clear none of those gates and the test applies, at which point the question becomes how far you have to look. For the mechanics of the test and how it meshes with the Exception Test, see our explainer on the Sequential and Exception Tests. If the site sits in Flood Zone 1 but inside a Critical Drainage Area, assume the first gate is met.

When can a flood risk assessment replace the Sequential Test?

Only where the risk is surface water, and only on a planning application. Paragraph 27 sets its carve-out inside NPPF paragraph 175, the exemption for sites a flood risk assessment shows to be free of flood risk, and asks for that paragraph to be read proportionately where surface water is concerned. It does not disapply the test for fluvial or tidal risk, and it does not reach Local Plan site allocations.

A site in Flood Zone 3 still needs a Sequential Test however good its flood risk assessment is. The carve-out reaches surface water and nothing else.

"Demonstrates clearly" is doing a great deal of work in that sentence, and it is where these submissions come unstuck. The Lead Local Flood Authority, not the Environment Agency, is the body that judges it, and six things generally have to be in the assessment first.

1. Modelled surface water depths, velocities and hazard ratings across the site, in the design event and with the climate change allowance applied.
2. Finished floor levels with freeboard above the modelled level, and a levels strategy that does not simply push water next door.
3. Safe access and egress for occupiers and emergency vehicles in the design event, not a dry building footprint alone.
4. Exceedance routing for events beyond the design standard, showing where water goes once the system is overwhelmed.
5. Drainage designed to the discharge rates and storage the LLFA requires, with maintenance that holds for the lifetime of the development.
6. An explicit lifetime assumption, usually 100 years for residential, with the climate change epoch and allowance band used to reach it.

That last point does more damage than people expect. "For the lifetime of the development" pulls the climate change allowances into the argument, so a scheme safe today but not in a century's time does not qualify. The data keeps moving too: the May 2026 update to the Flood Map for Planning brought surface water climate change data into the national mapping, and sites that screened clean before it may not now. Our guide to surface water flooding and planning covers the design side.

How wide does your area of search have to be?

As wide as the catchment for that type of development, and no wider. Paragraph 27a is the new paragraph and the most useful of the four, because it finally gives applicants something to argue with. The search area is "governed by local circumstances relating to the catchment area for the type of development proposed and the needs it is proposing to address", and should be "appropriate to the nature and scale of the proposal and the settlement it is proposed for".

That town-or-village limb is the PPG's worked example for non-major housing. Several published summaries quote it as though it were the general rule. It is not.

A 200-dwelling scheme cannot lean on it. What a major scheme can lean on is the principle above it, which is proportionality to the nature, scale and settlement of the proposal.

Settle the search area early, in writing, at pre-application. One agreed with the case officer before you spend money on a site sift is worth considerably more than a well-argued one submitted cold. Because the boundary turns on local circumstances, it is worth reading what your council's own local requirements and validation list ask for, and screening candidates on the current Flood Map for Planning rather than an older SFRA extract.

Which alternative sites count as "reasonably available"?

Three tests, all of which have to be met. Paragraph 28 defines a reasonably available site as one whose location is suitable for the type of development proposed, that is able to meet the same development needs, and that has a reasonable prospect of being developed at the same time as the proposal.

• Suitable location. Suitable for the type of development proposed, not simply vacant land in a lower Flood Zone.
• Same development needs. A site that cannot deliver what the proposal delivers is no alternative to it.
• Same timeframe. A reasonable prospect of being developed at the same time, which rules out land with no realistic route to delivery.
• Ownership is irrelevant. Alternative sites "do not need to be owned by the applicant to be considered 'reasonably available'".
• Smaller sites can combine. The paragraph expressly contemplates "a series of two or more smaller sites" together accommodating the development.

The hardest evidence to produce is now the negative: showing why an off-market site you do not own is not reasonably available.

Ownership is the limb that catches developers out, and it is less new law than codified law. The courts had already reached the same conclusion in Mead, which our note on applying the Sequential Test post-Mead works through. What paragraph 28 adds is that the point can no longer live in a footnote. A sift that discounts land on ownership alone will not survive scrutiny.

Does a housing land supply shortfall help?

Not with the test. Paragraph 27 is explicit that "the absence of a 5-year housing land supply is not a relevant consideration in applying the sequential test for individual applications". It then adds the qualification most summaries drop: "However, housing considerations, including housing land supply, may be relevant in the planning balance, alongside the outcome of the sequential test."

Two different questions, and worth keeping apart. Land supply cannot widen or soften the test. It can still carry weight on the other side of the balance once the test has been applied and its outcome is known, which is the territory the Yatton judgment went into.

What to put in a Sequential Test submission

1. The flood risk at the site from every source, with the date and version of the mapping used.
2. The area of search, justified against paragraph 27a by development type, catchment and settlement.
3. The date of the search and every source interrogated: Local Plan allocations, the SHLAA or HELAA, the brownfield register, live and recently determined permissions, agents' listings.
4. Every candidate the search threw up, not only the ones that were easy to reject.
5. A sift of each candidate against all three limbs of paragraph 28, giving the reason it fails in those terms, with its flood risk shown on the current Flood Map for Planning rather than an older SFRA extract.
6. Where you rely on the paragraph 27 route instead, a cross-reference to the part of the FRA that demonstrates lifetime safety from surface water.

The date of the search matters nearly as much as the search. A sift that predates the application by a year invites the objection that a lower-risk site has come forward since.

Refresh it before determination if the application has been running for months, and again before any appeal. In our experience the Sequential Test is one of the first things a validation officer looks for, and a thin one is a common reason a submission gets bounced at validation. Our note on planning appeals in 2026 sets out why repairing it later has become the expensive option.

What the September 2025 update did not change

• The Exception Test. Passing the Sequential Test, or being exempt from it, says nothing about whether the Exception Test applies. That still turns on Flood Zone and vulnerability classification.
• The Flood Zones. Zone 1, 2 and 3 definitions are untouched, so our flood zones explainer still holds.
• The NPPF. No Framework paragraph changed on 17 September 2025. What comes next is the draft NPPF, which would take these principles further.
• When an FRA is required. The validation triggers for a site-specific flood risk assessment are unchanged.
• Wales. The guidance is England-only, and Welsh applications continue to run on TAN15.

Frequently asked questions

If you need a Sequential Test that will stand up to an LLFA, a case officer or an Inspector, our Sequential and Exception Test reports set out how we scope the area of search, evidence the site sift, and prove the paragraph 27 route where it is genuinely available.