Can the Sequential Test Be Reformed to Unlock Homes?

The policy intent: clear enough

Paragraph 174 of the December 2024 NPPF states that:

Following the Court of Appeal's decision in Mead Realisations Ltd v Secretary of State, it is now settled that Planning Practice Guidance (PPG) can lawfully require a Sequential Test even where the NPPF does not explicitly demand one. This includes sites at risk of surface water flooding.

In principle, the Sequential Test remains an important strategic tool. It aims to ensure that new development is located, wherever possible, in areas with the lowest probability of flooding. This reflects a risk-avoidance approach — particularly relevant for developments proposed in areas identified as Flood Zones 2 or 3, or in locations subject to significant surface water hazard.

However, the current approach to the Sequential Test increasingly brings its application into tension with site-specific flood risk assessments and practical design solutions. As set out in this overview of the Sequential and Exception Tests, the Sequential Test should not be applied mechanically. The test is not about eliminating all risk, nor does it override national objectives around housing supply. Rather, it is intended to ensure that development is steered away from areas where risk cannot reasonably be managed.

In many planning contexts, however, the Sequential Test is being triggered by precautionary mapping alone — without due consideration for mitigation, drainage strategy, or site-level constraints. This not only results in an overly burdensome evidentiary process, but also creates inconsistency when the Sequential Test is applied to minor or localised areas of surface water risk that pose no realistic threat to development. As a result, the practical value of the test is diminished, and its purpose distorted.

When surface water flags trigger sequential testing

Surface water mapping in the UK tends to be precautionary in nature, often relying on digital terrain models that do not capture features such as existing drainage infrastructure, engineered overland flow paths or minor site-level variations in topography. As a result, some sites may be flagged as at risk of surface water flooding even where the underlying risk is shallow, isolated, or clearly manageable through standard mitigation techniques. While the mapping is valuable for strategic screening, in our experience it is essential that any sequential testing requirement be informed by site-specific assessment of actual flood pathways and the feasibility of mitigation. This leads to large areas being classified as at risk due to shallow ponding or minor depressions with limited hydrological connectivity. As highlighted in the 2025 update to the EA Flood Map for Planning, these surface water overlays are now being used more routinely by LPAs as triggers for the Sequential Test, even where Flood Risk Assessments demonstrate that risk can be addressed by modest changes in site levels, drainage design or attenuation.

In practice, this means applicants are increasingly required to undertake full Sequential Test exercises for sites where the risk is both minor and design-resolvable. These assessments often involve desktop reviews of alternative parcels across entire settlement hierarchies or housing market areas, imposing a significant time and cost burden. As set out in our analysis of housing delivery and flood risk, this blanket application of the Sequential Test to all surface water risk categories risks undermining sound planning judgment. It conflates theoretical mapping outputs with actual site conditions and penalises sustainable development proposals on sites that pose no real-world flood hazard to people or property.

This rigidity means the Sequential Test is applied to sites where there is no meaningful risk to future occupiers or off-site receptors. It also ignores the fact that mitigation (e.g. land raising, drainage schemes) can design out the risk. This trend has been exacerbated by updates to national flood mapping. As explained in the updated EA Flood Map for Planning (2025), new overlays for surface water risk are pulling more sites into Sequential Test territory, even where the underlying risk is low or manageable.

In the Faversham appeal, the Inspector allowed 250 homes on a site subject to both tidal and surface water flood risk. No Sequential Test was submitted. But design solutions (e.g. land levels raised 300mm above flood level) and the shallow, self-contained nature of the pluvial risk meant there was, in the Inspector's words, "no real world harm". The Sequential Test's absence was not a "strong reason for refusal", as illustrated in the Faversham appeal decision.

In Yatton, the Sequential Test was attempted and failed. Twelve preferable sites were identified. And yet the appeal was still allowed. The site could be made safe, the need for housing was pressing, and flood risk would not be increased elsewhere. This reasoning is explored further in the Yatton appeal case.

These cases highlight a dangerous disjunction between national policy (which demands the test) and inspector-level decisions (which often allow schemes despite failure or omission).

The data: Sequential Test friction in a broken system

According to Lichfields' May 2025 report How long is a piece of string?, the average time to determine a major outline planning application has risen to 710 days — nearly double the 2014 average of 360 days. Even the longest determination time recorded in 2014 (660 days) is now faster than the mean time in 2024. Worse still:

• Only 4% of major outlines in 2024 were approved within the statutory 13-week period, down from over 20% a decade earlier
• 64% now take more than a year, with many exceeding two years
• The time taken just to secure outline permission now exceeds the total time it took to obtain both outline and reserved matters approval in 2014
• Planning by appeal is now on average six months faster than local determination, reversing the historic norm

Appeals like Faversham and Yatton illustrate a growing mismatch between policy and practice: even where the Sequential Test is not carried out or is failed, inspectors are increasingly allowing appeals where the site can be made safe and flood risk appropriately managed.

The Sequential Test is not the only driver of delay, but it is emblematic of the wider procedural and evidentiary burdens now facing applicants. Many LPAs continue to treat Sequential Test failures as determinative, even when no substantive flood risk remains post-mitigation. As a result, applicants are forced to produce exhaustive Sequential Test evidence and site comparisons — sometimes across entire housing market areas — purely to navigate theoretical risks that mapping data may exaggerate.

These findings reinforce the broader concern that insisting on full Sequential Testing for sites with minor or mitigable surface water risk is not just disproportionate — it's counterproductive. A more pragmatic approach is needed, one that distinguishes between theoretical mapping risk and actual, design-resolvable flood vulnerability.

Where we go from here

This practical guidance on applying the Sequential Test post-Mead emphasises the need for a proportionate, evidence-led approach — one that reflects both the intent of national policy and the realities of site-specific flood risk.

Experience from recent appeals demonstrates that when carefully scrutinised, the Sequential Test often contributes little value in situations where flood risk can be demonstrably mitigated through standard design measures. Instead, it introduces procedural complexity and uncertainty, particularly for sites that fall within areas identified as being at low or moderate surface water risk due to conservative national mapping methodologies.

To support a more effective and streamlined planning process, we advocate:

• A PPG revision to clarify when surface water risk genuinely necessitates a Sequential Test, especially where local drainage or landform conditions can neutralise that risk
• Greater emphasis on Flood Risk Assessments and site-specific evidence as the basis for determining acceptability, including consideration of drainage strategy, exceedance routing, and landform treatment
• A return to the Sequential Test’s original purpose — to steer development away from unacceptable risk, not to introduce delay where risk is understood and appropriately managed

This approach echoes broader planning objectives: increasing housing supply, reducing friction in decision-making, and ensuring that flood policy supports resilient outcomes without unnecessary constraint. As noted in UK Housing Plans and Flood Risk: Striking the Right Balance, the test must be applied with judgement — not as an automatic filter that frustrates good, deliverable schemes.

Government planning reform: a system under pressure

One year into the Labour's administration, planning reform remains a headline priority — but questions remain around whether the changes will deliver real progress within this parliamentary term. The Government has reaffirmed its goal to build 1.5 million homes within five years, reintroduced mandatory local housing targets via a revised Standard Method, and launched a national taskforce to unblock stalled sites.

A review of the National Planning Policy Framework has been initiated to simplify and accelerate delivery, and early-stage efforts are underway to increase capacity in planning departments through funding and recruitment support. The introduction of the “Grey Belt” concept, targeting limited development in underutilised areas of the Green Belt, also signals intent to free up land supply.

However, much of this reform effort remains at an early stage. Crucially, none of the current policy announcements have addressed one of the key technical bottlenecks in the planning system: the over-application of the Sequential Test to sites at low or mitigable risk. As discussed in UK Housing Plans and Flood Risk: Striking the Right Balance, truly unlocking housing delivery will require not just more land and faster determinations, but also a rationalisation of flood risk policy where it unnecessarily obstructs otherwise safe development.

Without further clarity — particularly on how policy burdens like the Sequential Test will be interpreted and applied — there is a risk that headline ambitions fall short in practice.

Final thought

The Sequential Test was never intended to make housebuilding a one-site-at-a-time race to the driest location. Yet in its current form, that is how it is often being used. The solution isn’t to discard the Sequential Test entirely. It is to restore it to its proper role: a tool to avoid flood risk where necessary, not a procedural hurdle that delays housing delivery without meaningful benefit.

If the Government is serious about meeting its 1.5 million homes target by 2029, it must address the disconnect between Sequential Test policy and practice — urgently. Those involved in promoting or assessing sites with any mapped flood risk — particularly surface water — should ensure that Sequential Test requirements are reviewed critically, informed by site-specific assessment, and proportionate to the actual hazard. For support with Sequential Tests or interpreting updated flood mapping, our technical team can help.