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Neighbourhood planning advice

Flooding and drainage

Any new development must have an assessment that gives adequate and appropriate consideration to all sources of flooding and proposed surface water drainage.

Any application made to a local planning authority must show that it would:

  • Not increase the flood risk to the site or wider area.
  • Follow the drainage hierarchy. This is to discharge surface runoff as high up the following drainage options as reasonably practicable (1 being highest and 4 lowest):
  1. To the ground (shallow infiltration)
  2. To a surface water body (eg watercourse)
  3. To a surface water sewer
  4. To a combined sewer
  • Follow the four pillars of sustainable drainage systems. These are water quantity, water quality, biodiversity and amenity.

Sites proposed for allocation through neighbourhood plans should have a robust assessment of the risk of flooding from all sources.

The assessment should follow the principles of the Sequential Test, to steer new development to areas with the lowest risk of flooding. You'll find more advice on our Information for Developers page in the Flood and Water Management section of this website.

The Environment Agency provides surface water flood risk mapping via the Flood Warning Information Service at GOV.UK.

For further information contact llfa@norfolk.gov.uk

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