Flood Risk Sequential Test – On Calmer Waters!

On 17 September 2025, the Ministry of Housing, Communities and Local Government (“MHCLG”) provided long-awaited guidance on the application of the flood risk sequential test.

This guidance came at a time when the flood risk sequential test was attracting significant criticism. Despite reforms being made to the test in the National Planning Policy Framework (“NPPF”) back in December 2024, the application of this test was still responsible for the delay of a reported 57,000 planned homes. 

Some viewed the December 2024 alterations as making the test more onerous on developers, given that it gave surface water flooding the same weight as fluvial flooding in the application of the test. A further issue was the NPPF stating that “development should not be allocated or permitted if there are reasonably available sites appropriate for the proposed development with a lower risk of flooding”. Yet, the NPPF provided no definition of what was meant by “reasonably available”. This created uncertainty over the application of the test.

However, it seems the rough waters have finally calmed for developers with the new guidance. 

The MHCLG guidance has set out that when applying the sequential test in the context of surface water flooding “a proportionate approach should be taken”. They go on to state that the sequential test does not need to be applied “where a site-specific flood risk assessment demonstrates clearly that the proposed layout, design, and mitigation measures would ensure that occupiers and users would remain safe from current and future surface water flood risk for the lifetime of the development… without increasing flood risk elsewhere”. Thus, the guidance suggests that mitigation measures will be taken into account in the decision on whether the test should apply to surface water flooding. This offers greater flexibility as it provides the opportunity for developers to avoid application of the test by planning ahead. 

Further, the MHCLG also provides clarification on what is meant by a “reasonably available” site. The guidance sets forth that “Sites should be considered ‘reasonably available’… if their location is suitable for the type of development proposed, they are able to meet the same development needs and they have a reasonable prospect of being developed at the same time as the proposal”, in addition to adding that “such alternative sites do not need to be owned by the applicant to be considered ‘reasonably available’”. Although this largely echoes the approach we have already seen taken by the Planning Inspectorate in cases including APP/D0121/W/24/3343144¹, this is still a valuable definition that will allow developers to navigate these waters with greater understanding.

Overall, this new guidance is a positive step for developers, providing useful insight in how to avoid the application of the flood risk sequential test in the context of surface water and greater clarity on how and which alternative sites will be considered.

1: https://acp.planninginspectorate.gov.uk/ViewCase.aspx?caseid=3343144