Whether you are a developer, an agent or an individual seeking planning approval, if your development is 100m² or more of construction area you will require sustainable drainage to manage on-site surface water (whether you require planning permission or not). These SuDS must be designed and constructed in accordance with the Welsh Government Standards for Sustainable Drainage and you must seek SAB approval independently from your planning approval. Construction can only begin once the 2 permissions have been granted.
Existing developments/construction work with planning permission granted or deemed to be granted (whether or not subject to any conditions as to a reserved matter) or for which a valid application has been received but not determined by 7 January 2019, are not required to apply for SAB approval.
However, SAB approval will still be required if the planning permission was granted subject to a condition as to a reserved matter and an application for approval of the reserved matter is not made before 7 January 2020.
Surface water drainage systems must be designed and built in accordance with the Statutory Standards for Sustainable Drainage, which can be found here: SuDS Standards