Understanding and assessing flood risk

You will need to include a sustainable drainage strategy with your planning application (including outline applications) if your development is:

• major development with surface water drainage
• development with surface water drainage in an area at risk of flooding¹ such as flood zones 2 or 3, or at high risk of surface water flooding

If you do not include sustainable drainage systems in these circumstances, you will need to provide the LPA with clear evidence of why their use would be inappropriate.

Your sustainable drainage system will need to provide benefits for water quantity, water quality, biodiversity and amenity. You should include all the information set out in Sustainable Drainage Systems² (paragraph 059). You can put it in a separate document or in the FRA.

In major developments your sustainable drainage system should also provide multifunctional benefits where possible. More information on multifunctional benefits can be found in What are sustainable drainage systems and why are they important?³

1. https://www.gov.uk/guidance/flood-risk-and-coastal-change#areas-at-risk-of-flooding
2. https://www.gov.uk/guidance/flood-risk-and-coastal-change#sustainable-drainage-systems
3. What%20are%20sustainable%20drainage%20systems%20and%20why%20are%20they%20important?