Sustainable Drainage Approval Body (SAB)

Page updated on: 11/04/2022

The Flood and Water Management Act 2010 (Schedule 3) establishes SABs in County Councils and requires new developments to include Sustainable Drainage Systems (SuDS) features that comply with national standards. In our capacity as a SAB we will:

  • 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). Developers will need to enter into a legal adoption agreement as a part of the consent process.
  • approve but will not adopt a drainage system in a publicly maintained road. Publicly maintained roads are those to which section 41 of the Highways Act 1980 applies.

All new developments of more than 1 dwelling house or where construction area is 100m2 or more will need to submit a SuDS application demonstrating compliance with the statutory SuDs standards for the design, construction, operation and maintenance of surface water drainage systems serving new developments.

You can submit your application as a separate application or alongside your planning application.

Construction work must not commence unless the drainage system for the work has been approved.

SuDS can be used effectively in both rural and urban areas to support new development and redevelopment, whilst reducing the risk of surface water flooding and creating opportunities for improved water quality, bio-diverse rich habitats and new community recreational spaces.

This legislation came into force from January 7th 2019. Existing sites and developments with planning permission granted or deemed to be granted (regardless of whether 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, will not be required to submit a SuDS application.

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.

All construction work which has drainage implications where the development or redevelopment is more than a single dwelling house or involves the construction of a building or other structure covering an area of land equal to or greater than 100 square meters (unless it falls under one of the specific exemptions or transitional arrangements) requires SAB approval.

In the legislation for sustainable drainage:

  • Construction work means anything done by way of, in connection with, or in preparation for the creation of a building or other structure, and
  • Construction work has drainage implications if the building or structure will affect the ability of the land to absorb rainwater.
  • Construction area is generally defined in the regulations for sustainable drainage as the construction of a building or other structure covering an area of land of 100 square metres or more.


We are not responsible for approving and, as a consequence do not adopt, a drainage system which:

  • forms part of the strategic road network
  • forms part of the national rail network
  • forms part of a harbour
  • serves permitted development under 100m2 and
  • is constructed by the internal drainage board under its functions in the Land Drainage Act 1991.

We currently offer a free pre-application service to discuss in detail your site’s drainage requirements and what needs to be submitted with your application.

This will ensure suitability of proposed SuDS design in line with national standards and adequate site layout. We strongly recommend that you use this service before you submit your full application, to limit delays to approval and reduce cost in the long term.


You will need to provide the following information with your application.

Once we have received your completed application with all the required documents and the correct fee we will process your application within 7 weeks. If the development is subject to an EIA application under the Town and Country Planning (Environmental Impact Assessment) (Wales) Regulations 2017 it can take up to 12 weeks.

What is the normal timeframe for decision?

• A decision is taken on the valid application by the SAB Team within 7 weeks.

• If the development is subject to an Environmental Impact Assessment (EIA) it can take up to 12 weeks.

• If the decision cannot be made within the 7 or 12 week time scale due to additional information being required or due to the requirements of consultees then we will ask you to agree to an extension of time.

• Please note that valid applications can be approved or refused.

• Approved valid applications will often have conditions attached that must be complied with before construction work can commence on site. Please note that construction work includes site preparation works for the whole development.

What is a valid application?

• Information is provided to the SAB for assessment as required and outlined within the application form and includes the payment of an appropriate fee.

How do I improve my chances of success?

• To increase the likelihood that a SuDS Full Application is successfully validated we recommend that you submit an initial free SuDS Pre-Application. The SuDS Pre-Application simply outlines in principle how you intend managing the surface water from your development. The SAB team can then provide you with feedback regarding your drainage proposals prior to you submitting and paying for a SuDS Full Application.


Fees are calculated based on the size of the construction area.

  • You do not need to apply for construction areas less than 100m2 (unless the application is for more than one dwelling).
  • You need to submit the appropriate fee with your application.
  • There is a 50% reduction for applications submitted by community councils.

Fee Calculator

Additional fees

If your application is approved and subject to a condition that an inspection(s) of the SuDS scheme is undertaken, there is an inspection fee of £168 for each inspection.

Approved applications could also incur additional fees for temporary bonds that may be required to secure the construction work, together with a funded maintenance plan for the drainage system. These costs vary dependent on the nature and scale of the work. You will be made aware of the requirements as part of the approval process. If you are unsure of any aspect of the fees contact the SAB team directly.

These fees are based upon The Flood and Water Management Act 2010, Schedule 3, The Sustainable Drainage (Application for Approval Fees)(Wales) Regulations 2018.

You will need to provide the following details when making your payment - type of application, application reference number or name and application location if you do not have a reference number yet and the correct application fee.

  • By Telephone - We accept Maestro, Solo or Visa debit cards. If you’d like to speak to a member of staff in the cashier's team - call 01267 228686 during office hours, 9am - 5pm.
  • By post - Make cheques payable to ‘Carmarthenshire County Council’ and post to: SAB Registrations, Civic Offices, Crescent Road, Llandeilo, SA19 6HW.
  • In Person - You can make a cash, credit/debit card or cheque payment at your nearest Hwb in Ammanford, Carmarthen or Llanelli.
  • BACS Payment - email for further details and to set up a BACS payment.

Securing a sustainable funding mechanism for the lifetime of development is a key objective of the SuDS Approving Body (SAB). The SAB has a responsibility for the management and maintenance of SuDS assets after they have been adopted. Therefore commuted sum aims to ensure that the SAB has the resources to cover the upkeep and (where appropriate) the replacement of the assets they have adopted. The effectiveness of SuDS and the associated multiple benefits will rely on appropriate maintenance.

In order to ensure consistency throughout Wales, the use of the industry standard guidance “Commuted Sums for Maintaining Infrastructure Assets” prepared by the CSS (County Surveyors Society), is to be used, to calculate commuted sums for all drainage assets being adopted by the SAB, whether that be through a S38 agreement or a bespoke legal agreement for the life of the developments (60-120 years).

The calculation of a commuted sum includes consideration of:

  • The estimated periodic maintenance cost of the asset to the adopted e.g. every six months. The SuDs manual provides useful information on this element.
  • Its future cost of renewal or replacement (e.g. permeable paving has design life of 20 years, over the lifetime of the development this could lead to 3 replacements).
  • The duration over which the sum is required. The Association of Directors of Planning and Transport recommends commuted sums for structures should be calculated to cover a 120-year period and that the period for other items should be 60 years (basically the whole life of the development).
  • The effective annual interest rate that will provide a return on the sum invested prior to its expenditure after the effects of inflation have been taken into account (called the discount rate approx. 2.2%).

The use of the CSS guidance is recommended to provide a common understanding for developers and the SAB.