NPPF 2026: What’s changed for flood risk and drainage?
For architects, planners, developers and other property professionals, understanding planning requirements early is essential to increase the chances of planning being approved on the first attempt.
The National Planning Policy Framework (NPPF) is an essential resource for planning applications. It sets out how Local Authorities must design their local development plans and review planning applications.
The latest revision of the NPPF, published in August 2026, introduces several important updates to flood risk and drainage requirements.
In this post, we look at the key changes property professionals need to be aware of when it comes to flood risk and drainage and what they could mean for future development projects.
A dedicated chapter for flood risk
One of the most noticeable changes is that flood risk now has its own dedicated chapter (Chapter 18).
Previously considered alongside climate change, the new structure gives flood risk greater prominence and makes the relevant national planning policies easier to navigate.
The chapter brings together requirements covering flood risk and sustainable drainage.
While many of the core principles will already be familiar to property professionals, the new structure provides greater clarity around how flood risk should be considered when allocating land for development and determining planning applications.
For developers considering a site, this makes early flood risk screening particularly valuable. Understanding potential constraints before progressing a design or planning application can help establish whether further assessment, such as a Flood Risk Assessment (FRA) or Sequential Test, is likely to be required.
Greater clarity around the Sequential Test
The updated NPPF provides further clarity around when a Sequential Test, specifically for flood risk, is required.
The Sequential Test continues to apply where proposed development may be at risk from any source of flooding, either now or in the future. However, the NPPF also identifies circumstances where a Sequential Test may not be necessary.
For example, where the only identified risk is from surface water flooding, a Sequential Test may not be required where a site-specific Flood Risk Assessment can demonstrate that the development can be designed and mitigated to keep users safe throughout its lifetime without increasing flood risk elsewhere.
A Sequential Test may also not be necessary where an FRA demonstrates that built development, access and escape routes and other vulnerable elements can be located outside areas at risk of flooding.
GeoSmart’s Flood Risk Assessments and Sequential Tests can help establish the level of flood risk affecting a development and provide the evidence required to support a planning application.
Proportionate Sequential Test search areas
Where a Sequential Test is required, the updated NPPF also provides additional clarity around the geographical area used to search for reasonably available alternative sites.
The search area should not be greater than the anticipated catchment of the development in terms of its likely occupiers.
This will provide a more proportionate approach for some developments and help applicants define and justify an appropriate search area based on the nature of their proposal.
GeoSmart can undertake Sequential Tests for planning applications, assessing reasonably available alternative sites against flood risk.
Greater emphasis on future flood risk
Another important theme in the updated NPPF is the need to consider how flood risk could change over the lifetime of a development.
This is particularly relevant following recent updates to the Environment Agency’s Flood Map for Planning, which provides property professionals with more information about potential future flood risk.
For developers undertaking due diligence, relying on a site’s current Flood Zone alone may therefore not be enough.
Understanding both current and future flood risk at an early stage can help identify potential constraints, inform site layouts and determine what assessments may be required before a planning application is submitted.
National Sustainable Drainage Systems (SuDS) Standards given greater prominence
The updated NPPF also strengthens the role of SuDS within development.
Developments that could affect drainage on or around a site should incorporate SuDS proportionate to the nature and scale of the development.
Importantly, the NPPF now explicitly states that SuDS should be designed in accordance with the latest National Standards for Sustainable Drainage Systems.
For developers and design teams, this further reinforces the importance of considering surface water drainage from the earliest stages of a project.
Understanding whether infiltration is feasible, how much surface water runoff a development could generate and where that water can ultimately discharge can all influence site layouts and the amount of land required for drainage features.
GeoSmart provides support throughout the drainage process, including drainage assessments, drainage strategies, infiltration testing and detailed drainage design.
The importance of long-term SuDS maintenance
The updated NPPF doesn’t just focus on how a drainage system is designed. It also highlights the need for appropriate maintenance arrangements to ensure SuDS continue to operate to an acceptable standard throughout the anticipated lifetime of a development.
For major developments, advice from the Lead Local Flood Authority (LLFA) should also be taken into account.
This makes it increasingly important for drainage strategies to consider not only how surface water will be managed, but how drainage features will be operated and maintained in the longer term.
A greater focus on natural watercourses
The updated NPPF discourages the enclosure of existing watercourses unless there are compelling reasons to do so.
Where appropriate, developments should consider opportunities to remove existing culverts and renaturalise river channels, provided this can be achieved without increasing flood risk or causing unacceptable environmental or heritage impacts.
For larger developments in particular, existing watercourses should therefore be considered as part of early site planning rather than simply as constraints to be engineered around.
What do the NPPF changes mean for property professionals?
Many of the fundamental principles behind flood risk and drainage remain the same. However, the August 2026 NPPF provides greater clarity around flood risk assessments and Sequential Tests, places more emphasis on current and future flood risk and strengthens the role of sustainable drainage in development.
Identifying potential constraints at the beginning of a project can help establish what assessments will be required, inform the development layout and reduce the risk of unexpected issues emerging during planning.
GeoSmart can support projects throughout this process, with services including:
- Flood Risk Assessments (FRAs)
- Flood Risk Sequential Tests
- Flood Warning and Evacuation Plans
- Sustainable drainage assessments and strategies
- Detailed drainage design
- Management and maintenance plans
- BRE 365 infiltration testing
- Flood risk, groundwater and drainage data
- Basement impact assessments
Whether you’re assessing the viability of a potential development site or responding to a planning requirement, our flood risk and drainage specialists can help identify what you need and support your project through the planning process.
Need help understanding the flood risk or drainage requirements for your site? Get in touch with the GeoSmart team to discuss your project.
