Permission for Drainage

Since 7 January 2019 a significant change to drainage requirements has been introduced across Wales.

Schedule 3 of the Flood and Water Management Act (FWMA) 2010 requires surface water drainage for new developments to comply with mandatory National Standards for sustainable drainage (SuDS).

It also requires surface water drainage systems to be approved by a SuDS Approving Body (SAB), before construction work with drainage implications may begin. With the exception of single curtilage sites, the SAB has a duty to adopt these systems.

Blaenau Gwent County Borough Council is working in partnership with Merthyr Tydfil County Borough Council to process all applications for developments within Blaenau Gwent that are more than a single dwelling or have a construction area of more than 100 square metres. Applications for sustainable drainage approval for these developments will need to apply to Merthyr Tydfil County Borough Council by clicking the link Here.

All developments with drainage implications for a single property or development under the threshold of 100 square metres are exempt from SAB approval, but will still need Planning/Drainage approval.  Consent for these applications can be obtained via the planning process, or if your application is not subject to planning consent, by seeking approval via email to

Some questions answered

Schedule 3 and the Flood Water Management Act – How does it affect BGCBC?
Schedule 3 establishes SABs in unitary authorities and the FWMA gives those bodies statutory responsibility for approving, and in some cases adopting, the approved drainage systems.

What is a SAB and how it affects my development?
The SAB is established to:

  • Evaluate and approve drainage applications for new developments where construction work has drainage implications, and
  • Adopt and maintain surface water drainage systems according to Section 17 of Schedule 3 (FWMA).

Surface water drainage systems serving new development must be designed and built in accordance with standards for sustainable drainage published by Welsh Ministers. These systems must be approved by the local authority acting in its SuDS Approving Body (SAB) role. 

When did the SAB come into effect?
The Commencement Order for Schedule 3 of the Flood and Water Management Act 2010 (the Act) was signed 1 May 2018. This set a start date for the approvals requirement of 7 January 2019.

Why are SuDs and the SAB important?
The requirement to consider SuDS in all new and redeveloped sites is being driven by existing and increased local flooding, increased pollution of our rivers, poor natural landscapes, declining biodiversity and uncertainty regarding the impact of climate change.

In particular, traditional piped/underground systems that collect runoff from hard paved surfaces such as roofs, roads and car parks are unsustainable and have contributed to increased flood risk and pollution by:

  • Increasing the volume and rate at which surface water is discharged to a receiving watercourse and therefore increasing fluvial flood risk;
  • Surcharging during larger rainfall events, with water unable to discharge to the system or emerging through manholes and gullies in areas at lower elevation hence causing localised pluvial flooding;
  • Partial or full blockage caused by sediment, debris or pipe collapse which can often go unnoticed until a large rainfall event causes flooding in upstream areas;
  • Little to no treatment of surface water runoff, especially from vehicular areas, thereby conveying all pollutants to the natural environment;
  • Increased discharge of surface water runoff to combined sewers or wastewater treatment works.

The scale of urbanisation and society’s attitude towards the management of surface water is exacerbating existing issues. It is therefore essential that any new development is required to incorporate sustainable drainage principles. This will help change attitudes towards living with water and mitigate the effects of urbanisation thereby prevent further deterioration.

In relation to SuDs, Welsh Government policy objective is to deliver effective, multi-purpose SuDs in new developments that will be maintained for the life-time of the development they serve. 

Are all developments required to have SAB approval?
It is currently proposed that with the exceptions of single dwellings and developments with a construction area less than 100 square metres, all construction work that has drainage implications will need SAB approval.

Existing sites and developments which have planning permission, have been agreed or deemed to have been agreed (whether or not they are subject to any conditions regarding reserved matters) or for which a valid application was received but not decided upon by 7 January 2019, do not require approval of the Sustainable Drainage Systems Approval Body.

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 was not made before 7 January 2020.

What is the best way to proceed with gaining approval?
Drainage systems should be considered at the first stages of site design to maximise benefits. This will influence the layout of the roads, buildings and public open spaces. We recommend that you refer to the Non-Statutory Ministerial National Standards and CIRIA C753: The SuDs Manual. 

Planning of a new site layout should be integrated and sympathetic to the existing topography and the requirements of surface water management systems, to both effectively manage and treat surface water runoff while improving water quality. Any existing watercourses, ditches, and other drainage features both within and adjoining should be preserved and incorporated into development. The above will assist in providing the biodiversity, amenity benefits and cost effective design. 

National Standards published by Welsh Ministers contains a number of drainage design principles and a set of six standards. Drainage designers will need to demonstrate how their proposed drainage for a new development complies with these.

Is the SAB approval application separate to the planning system?
The SuDs Approval process is a technical approval process. Applications for approval of sustainable drainage on new developments will need to be made to the SAB. While this process will be separate from the planning application process, discussion and consultation between the Local Planning Authority (LPA), the SAB and the developer will need to take place from the pre-application stage to ensure suitability of proposed SuDs design in line with national standards, adequate site layout and ultimately SAB approval.

Pre-application discussion can help ensure the applicants are fully aware of requirements at the outset, thereby limiting delays to approval and reducing cost in the long term. 

Is it possible I can get more information about Sustainable Drainage Systems?
As we get closer to the implementation process we will be publishing more information on this website, including details of the application and approval process.

The following webpages are a useful free resource to gain more information on Sustainable Drainage.

Welsh Government has provided a lot of information on the implementation process and is available on their website at

If you would like more information about this new process then please “contact us