Sustainable Drainage Systems (SuDS)

Sustainable Drainage Systems (SuDS) aim to manage rainfall in a way similar to natural processes, making use of the landscape and natural vegetation to control the flow and volume of surface water. SuDS can deliver many benefits including:

  • flood risk reduction,
  • improved water quality,
  • opportunities for habitat creation,
  • enhanced biodiversity,
  • supporting well-being through bringing people closer to green and blue community spaces.  

Schedule 3 of the Flood and Water Management Act 2010 (external website) makes SuDS a mandatory requirement on all new developments involving more than a single dwelling or a construction area more than 100m2. The law applies whether you are a developer, an agent or an individual seeking planning permission for a development.

New developments of more than a single dwelling or a construction area more than 100m2 must have:

  • Sustainable drainage systems to manage on-site surface water
  • Surface water drainage systems designed and built in accordance with mandatory Welsh Government standards for sustainable drainage
  • Approval of the surface water drainage systems by the SuDS Approving Body (SAB)

You must get SAB approval separately from planning permission. Construction can only begin when SAB approval and planning permission have been granted.

SuDS Approving Body (SAB)

Local Authorities are the SuDS Approving Body (SAB) and we are the SAB for Denbighshire. SABs make sure that drainage is designed and built according to the national standards for sustainable drainage and;

  • provide a pre-application service to discuss your proposal
  • evaluate and approves drainage applications for new developments where construction work has drainage implications, and
  • adopts and maintains surface water drainage systems
  • has powers to inspect systems and take enforcement action where required

Before you apply for SAB approval

Welsh Government recommend that you consult with the Local Planning Authority and SAB from the pre-application stage onwards. This is to ensure;

  • the proposed SuDs design is suitable and in line with national standards
  • adequate site layout
  • SAB approval

Getting SAB approval is separate from the planning application process. We've developed a drainage strategy questionnaire that we recommend you submit with any planning application before you apply for SAB approval.

Find out more and download the drainage strategy questionnaire for developments with drainage impacts.

How to get SAB approval for SuDS

You'll need to complete a SuDS full application form to apply for SAB approval. You can complete a SuDS pre-application form to discuss in detail your site, drainage requirements and what needs to be submitted with your full application.

SuDS pre-application

We recommend that you use this service before you submit your full application, as it can limit delays to approval and reduce cost in the long term.

SuDS pre-application form (MS Word, 277KB)

SuDS full application  

SuDS full application form (MS Word, 241KB) 

SuDS full-application fees

View the application fees for SuDS applications (external website).

SuDS approval of conditions

SuDS approval of conditions application form (MS Word, 202KB) 

Where SAB approval isn’t needed

You do not have to apply for SAB approval if:

  • planning permission is not needed for your development and the construction area is less than 100m2
  • your development is for a single dwelling house, or other type of construction, which covers an area of land less than 100m2
  • your development has planning permission granted before 7th January 2019
  • planning permission for your development is deemed to be granted (with or without any conditions about a reserved matter)
  • your development has a valid application received by us by 7th January 2019, but it has not been determined.