Sequential Test
A planning requirement to steer development to areas of lowest flood risk. Applicants must demonstrate that no reasonably available alternative sites exist in areas of lower flood risk.
The Sequential Test is a fundamental principle of flood risk management in the planning system, established by the National Planning Policy Framework. Its purpose is to steer new development to areas at the lowest risk of flooding, ensuring that sites in Flood Zone 1 are developed in preference to those in Flood Zone 2, and Flood Zone 2 in preference to Flood Zone 3.
The applicant is typically required to submit a Sequential Test report alongside the Flood Risk Assessment. This report identifies the search area (usually the local authority boundary, unless otherwise agreed), defines the development requirements, and systematically assesses alternative sites for their availability, suitability, and flood risk.
Key considerations in a Sequential Test include:
- The agreed search area and the development type being proposed
- Whether alternative sites are genuinely “reasonably available” — not just any vacant land
- The flood risk of each alternative, using Environment Agency flood maps and SFRA data
- Whether the alternative sites could accommodate the proposed development
The Sequential Test is applied by the local planning authority, not the Environment Agency. If the test cannot be passed, the Exception Test may be required as an additional hurdle.
In some cases, the local authority’s own evidence base (such as site allocations in the Local Plan) means the Sequential Test has already been applied at the plan-making stage, and a site-level test is not required. Aegaea advises on the Sequential and Exception Test process as part of our flood risk assessment service.