The recent updates to the National Planning Policy Framework (NPPF) (December 2024) and the accompanying Planning Practice Guidance (PPG) (September 2025) have brought significant clarification on how flood risk must be assessed in the planning process.

The changes have expanded the scope of The Sequential Test to include all types of flooding, including surface water.

Previously, the Sequential Test, the process that guides where developments should be located based on flood risk, was primarily focused on fluvial (river) and tidal (coastal) flood risk. Surface water flooding, while relevant, was often treated as secondary or dealt with separately through site-specific assessments. The updated NPPF and PPG now explicitly require the Sequential Test to consider ‘all sources of flood risk’, including surface water, groundwater, reservoir, and sewer flooding, and reinforce that this must include current and future risk, considering climate change allowances and projected rainfall intensities.

It also clarifies that mitigation measures alone (such as drainage improvements or SuDS) are not sufficient to bypass the need for the Sequential Test if a site is already at risk.

In simple terms, developments now need to demonstrate that they are in the lowest reasonably available flood risk area, considering every flood source, not just rivers and coasts.

Surface Water exemptions

Previously flooding from surface water could be dealt with through site-specific assessments and the updated PPG does allow for limited exceptions for individual planning applications where a robust Flood Risk Assessment (FRA) can demonstrate that the development would be safe from surface water flooding, both now and under climate change scenarios, and the proposal would not increase flood risk elsewhere.

Flooding from Surface Water is the new single exception from this requirement. Where a site-specific FRA can demonstrate a development is not at increased risk from surface water flooding during its lifetime, nor does it increase the risk elsewhere, then the sequential test need not be applied.

Early involvement of civil engineers becomes strategically important

The Sequential Test now demands a quantitative understanding of surface water behaviour, which can only be provided through high-quality civil engineering input.

By modelling surface water flow paths and flood extents, our civil engineers can advise clients before land acquisition or design development, adding significant value to the planning process.

The inclusion of surface water in the Sequential Test strengthens the link between flood risk, drainage, and SuDS design. We can now integrate hydraulic modelling, drainage strategy, and site grading more holistically, improving both compliance and long-term sustainability.

Advantages for developers and clients

While these updates may seem to add another layer of complexity to the planning process, they actually offer clear benefits for developers and landowners who approach flood risk proactively.

Reduced long-term risk and liability

By considering surface water flood risk from the outset, developers can avoid sites that will later face planning resistance or insurance challenges, reducing financial exposure.

Faster, More Certain Planning Approvals

When supported by a robust Sequential Test and Flood Risk Assessment (FRA) prepared by experienced civil engineers, planning applications are less likely to be delayed or refused on flood risk grounds. Early consideration of surface water flooding demonstrates compliance and confidence to planning officers and the Environment Agency.

Stronger design integration with SuDS

SuDS (Sustainable Drainage Systems) directly manages surface water runoff, integrating SuDS early into design not only meets NPPF and Building Regulation requirements but also enhances a site’s features, biodiversity, and long-term value.

By addressing surface water flooding comprehensively, developers are future-proofing projects against ever-tightening environmental and climate regulations. This strategic alignment is increasingly attractive to planning authorities and investors but developers benefit from more sustainable and attractive schemes.

What this change means in practice

Surface water flood risk now matters as much as river or coastal flooding, and it pays to address it early, with expert civil engineering input. The updated policy underscores the importance of technical expertise. Water management is no longer an afterthought — it’s a core planning consideration.

In light of these updates, clients may want to reassess site selection criteria to include surface water flood mapping and incorporate surface water modelling early in the master planning process. Close coordination with planning consultants might be needed to ensure Sequential Test justifications are robust and evidence-led, and use FRAs not just as compliance documents, but as design tools to influence site layout, SuDS design, and resilience planning.

At SWJ Consulting, our civil engineering team are ready to work with clients from the earliest stages to combine hydrology, hydraulic modelling, and sustainable drainage design — ensuring every project meets the NPPF’s risk-based approach while remaining viable and deliverable. We can also help you if you need to reassess site selection or master planning.

Give SWJ Consulting a call on 02381 920656 or email mail@swjconsulting.co.uk if you have questions or concerns about the what the 2024–2025 NPPF and PPG updates mean for your project.