Check the flood map
Start with the government’s flood map for planning, which shows Flood Zones 1, 2 and 3. Also check surface water flood risk, because a site in Zone 1 can still flood from heavy rainfall.
Flood risk assessments
A site-specific flood risk assessment (FRA) is required for most development in Zones 2 and 3, for sites of 1 hectare or more in Zone 1, and in some other circumstances. It shows how the development will be safe, for example through raised floor levels and safe access, and that it won’t increase flood risk elsewhere.
The sequential and exception tests
For new homes and other vulnerable uses in higher-risk zones, the sequential test asks whether there are reasonably available sites at lower risk. If the development can pass that, the exception test may also apply, requiring wider sustainability benefits and proof the development will be safe for its lifetime.
Householder extensions and changes of use generally don’t need the sequential test, but still need an FRA in flood zones.
Drainage
Councils expect sustainable drainage systems (SuDS) on most new development, managing rainwater on site through permeable surfaces, attenuation and planting. Basements in flood-risk areas face particular scrutiny.
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Sources
This article is general information about planning in England at the date shown. It is not advice on any particular site, and the law and policy may have changed since. Please speak to us before relying on it.