All developments of 1 hectare or over in flood zone 1, and any development in Flood zone 2 and 3 (including householders, minor development and change of use) need a flood risk assessment (FRA). This also applies if the main development is in zone 1 but the access lies in zone 3.
The FRA should address the issues of flooding to both property and people. The FRA should identify and assess the risks of all forms of flooding to and from the development and demonstrate how these flood risks will be managed, taking climate change into account.
Where necessary the sequential test should be applied, and only once this has been passed will the exceptions test be considered.
The FRA should identify opportunities to reduce the probability and consequences of flooding. The FRA should include the design of surface water management systems including Sustainable Drainage Systems (SUDs) and address the requirement for safe access to and from the development in areas at risk of flooding.
The submitted FRA should demonstrate whether the proposed development (including its access and egress) will be safe over its lifetime without increasing flood risk elsewhere. Where possible, it should demonstrate that it reduces flood risk overall.
Find out which flood zone your development is in by visiting the Government's flood map.
You can find out more in DEFRA and the Environment Agency's guidance on Flood Risk Assessment for Planning Applications (Gov.uk).