Understanding and assessing flood risk

Information on sustainable drainage systems is needed for all:

• 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 need to provide the LPA with clear evidence of why their use would be inappropriate.

You should include all the information set out in section 6 of the site-specific flood risk assessment checklist². 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.

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#Site-Specific-Flood-Risk-Assessment-checklist-section