In September 2025, the Government updated its Planning Practice Guidance (PPG) on flood risk and coastal change. These revisions significantly sharpen how planning applications should address flooding, especially in relation to the Sequential Test, search areas, and surface water risk. This is, in turn, changing the way Councils are looking at proposals in the context of such applications in more recent applications. So, what are the key changes?
Broader Scope of the Sequential Test
The updated guidance makes it clear that the sequential, risk-based approach must now apply to all sources of flood risk, not just rivers and the sea. That means surface water, groundwater, reservoirs, and other sources must be considered alongside fluvial and tidal risk, including future climate change effects. The objective remains to steer development wherever possible into Flood Zone 1, the lowest risk areas. We are seeing some Councils take this scope of assessment much further than before, and further than we expected, in the context of the information required as part of planning applications (of all types).
Carve-Out for Surface Water Risk
A new limited exemption allows developers to waive the Sequential Test at the application stage (but only for surface water risk). If a site-specific Flood Risk Assessment (FRA) convincingly demonstrates that the design, layout, and mitigation measures ensure occupiers’ safety for the full lifetime of the development (considering climate change), and that no increase in flood risk elsewhere will result, then the Sequential Test need not apply. However, this is likely to face close scrutiny as local planning authorities (LPAs) and Lead Local Flood Authorities (LLFAs) will expect high-quality evidence, robust modelling, and clear safe access/egress.
Proportionate Areas of Search and Redefining “Reasonably Available” Sites
The guidance now introduces greater proportionality in defining the “area of search” for the Sequential Test. Instead of blanket district-wide searches, applicants should tailor the search to local catchment, market and settlement geography. For example, for small non-major housing development, the search “would not usually” have to stretch beyond the immediate town or village and its neighbours. This change helps avoid unproductive comparisons with remote sites that are neither practical nor reasonable alternatives.
The notion of “reasonably available” sites has been clarified. Under the new guidance, alternatives need not be owned by the applicant — ownership is irrelevant. Multiple smaller plots, when combined, can also count, provided they meet the same development needs and are deliverable within the same timescales. This raises the evidential bar: applicants must justify why other sites, even outside their control, cannot realistically or timely accommodate their proposal.
Housing Supply Cannot Override Flood Safety
Crucially, the update asserts that a shortfall in housing land supply (e.g. a five-year supply) is not a relevant argument for avoiding the Sequential Test. While housing considerations remain part of the planning balance, they must not compromise flood safety.
Key Takeaways
With a stronger emphasis on future risk (climate change) and surface water, high-quality FRAs are more important than ever. Detailed hydraulic and rainfall modelling, assessment of exceedance flows, SuDS design and plans for safe access/egress will be essential, particularly if developers hope to rely on the surface water carve-out.
Given the tighter requirements and greater scrutiny, early engagement with LPAs, Lead Local Flood Authorities, and the Environment Agency is strongly advisable. Presenting clear, proportionate search area justifications and robust FRA evidence will help secure buy-in and reduce risk at the decision-making stage.
The PPG updates strengthen and clarify how flood risk should be managed in planning applications. While they restate the primacy of the Sequential Test, they introduce limited flexibility for surface water risk and insist on proportionate, evidence-based approaches. For developers, the message is clear: demonstrate safety and reasonableness clearly and do not, for example, rely on housing need to shortcut flood risk requirements.