When is an assessment needed?
Policy F4 of the NPPF published on 17 August 2026 expects a site-specific assessment for development in Flood Zones 2, 3a and 3b. In Flood Zone 1, the triggers include sites of one hectare or more, land identified by the Environment Agency as having critical drainage problems, and land identified in the strategic assessment or Flood Map for Planning as at risk from any source now or in the future. [1]
Do not rely on the phrase “low river-flood risk” to dismiss the question. Groundwater, surface water and other sources can matter. The Environment Agency's guidance explains the evidence needed and the importance of the proposal's use, location and vulnerability. [2] [3]
What does the report examine?
A proportionate assessment considers the relevant flood sources, the existing and proposed levels, access and escape, climate change and the effect on flood risk outside the site. It should explain the evidence, assumptions and mitigation, not merely attach a screenshot of a flood map. [3]
Ask the consultant to identify what is known from published information and what needs site-specific investigation. Where a proposed basement or changed ground level creates particular concerns, make sure those concerns are included in the brief rather than assumed to be covered by a generic report.
Who prepares it?
Use a suitably experienced flood-risk consultant or drainage/civil engineering professional whose competence matches the site. The national guidance allows the level of assessment to reflect the development's complexity; it also explains where professional advice is appropriate. [2]
Give the consultant the current site boundary, topographical information, floor levels and proposed use of each part of the development. Ask for a clear account of any changes needed to the design, so the architect can incorporate them before submission.
The sequential test is a separate question
An FRA does not automatically demonstrate compliance with every flood policy. Where required, the sequential test considers whether appropriate development can be located in a lower-risk area; the exception test has a separate purpose. National policy F5 contains exemptions from the sequential test, including householder development, but that does not remove an applicable F4 requirement for a site-specific assessment. [1]
The August 2026 policy also includes specific provisions for surface-water-only risk and proposals whose vulnerable elements avoid risk areas. Have the consultant apply the current policy to the actual layout rather than rely on a general statement that every flood-risk site needs the same tests. [1]
Coordinate the conclusions
An FRA and a drainage strategy answer related but different questions. Ask the reports to use consistent levels and assumptions, and identify which mitigation must appear on the drawings or be secured before work starts. [4]
Read the decision notice after approval and carry the agreed measures into the technical design. A report that depends on raised levels or a particular access arrangement is not still describing the scheme if those features are later removed.