What is the worst flood zone rating?

In the UK planning system, the flood zone with the biggest risk for you and your development is Flood Zone 3b, commonly referred to as the Functional Floodplain.

Under Environment Agency definitions, this zone comprises land where water must flow or be stored in times of flood.

Planning implications:

• Restrictions on Development: Only Water Compatible uses such as marinas, sand & gravel workings etc and Essential Infrastructure can take place. All other residential/commercial uses will be refused.
• Exception Test: There is no exception test available for More Vulnerable uses within Flood Zone 3b, therefore these types of uses will always be refused.
• Storage Capacity: Any proposal must ensure that it does not restrict the flow of water or the capacity to store water within the floodplain, thereby increasing the potential risks to nearby communities.

Flood Zone 3b represents the greatest constraints on land use and poses the greatest flood risk for a property.