As climate change increases the frequency and severity of flooding across the UK, planning policy plays a vital role in ensuring that new development is located safely and does not worsen flood risk. National policy emphasises two core principles:
- Direct development away from areas at medium and high risk of flooding
- Where development must occur in these areas, ensure it is safe for its lifetime and does not increase flood risk elsewhere
This document explains how these principles are applied through the Sequential Test and Exception Test.
1. Directing Development to Low‑Risk Areas: The Sequential Test
1.1 Considering All Sources of Flooding
When selecting a site, developers must consider flooding from:
- Fluvial sources (rivers, lakes)
- Surface water runoff
- Groundwater flooding
- Sewer flooding
- Coastal flooding
A site-specific Flood Risk Assessment (FRA) may be required depending on the location and type of development (more information is available at Flood risk assessments: applying for planning permission – GOV.UK).
1.2 When the Sequential Test Is Required
The Sequential Test applies to major and non‑major development (defined at appendix 2 of the governments Procedural guidance for Section 62A Authorities in Special Measures – GOV.UK) when any of the following apply:
- The proposal is in Flood Zone 2 or 3
- The site is in Flood Zone 1, but the FRA shows increased future flood risk
- The site is at risk from other sources of flooding, not just rivers or the sea
1.3 When the Sequential Test Is Not Required
The test is not needed if the FRA shows that no part of the proposed built development (including access routes, land raising, or vulnerable infrastructure) would be at risk from any source of flooding now or in the future.
1.4 How the Sequential Test Works
The test considers the catchment area relevant to the development (e.g., a school’s catchment). Within this area, the applicant and LPA must assess all reasonably available alternative sites. If lower‑risk sites exist, development should be directed to those locations.
Reasonably available sites are those sites which can meet the same development needs and have a reasonable prospect of being developed at same time as the proposal.
2. The Exception Test
If no suitable low‑risk sites are available, the Exception Test may allow development in medium‑ or high‑risk areas, but only if both conditions are met:
2.1 Sustainability Benefits
The development must provide wider sustainability benefits to the community that outweigh the flood risk. Local planning authorities are encouraged to define what counts as such benefits in their local plans.
2.2 Safety for the Development’s Lifetime
The development must be:
- Safe for its lifetime, considering user vulnerability
- Designed so it does not increase flood risk elsewhere
- Ideally contributing to an overall reduction in flood risk
Typical Lifetime Assumptions: While national policy does not specify a fixed duration, safety should be assessed over 70–100 years, depending on development type and climate change allowances.
Conclusion
The Sequential and Exception Tests ensure that new development:
- Is located as safely as possible
- Does not increase flood risk
- Supports long‑term climate resilience
These tools are essential for protecting communities and infrastructure as flood risk continues to rise.