New mandatory requirements for sustainable drainage systems (SuDS)

Published 12/11/2018   |   Last Updated 27/05/2021   |   Reading Time minutes

Orders were laid before the National Assembly on 15 October 2018, as part of a suite of statutory instruments (SIs) relating to sustainable drainage systems – or SuDS. These make provisions under Schedule 3 to the Flood and Water Management Act 2010, which make SuDS a mandatory requirement for all new developments.

A number of regulations have also been laid as part of the same suite of SIs, contributing to delivering objectives as part of the Welsh Government’s National Strategy for Flood and Coastal Erosion Risk Management in Wales. The suite of SIs are:

The two draft SIs before the Assembly for approval on Tuesday 13 November are the Sustainable Drainage (Enforcement) (Wales) Order 2018 and the Sustainable Drainage (Appeals) (Wales) Regulations 2018.

The Welsh Government say that the legislation “will ensure resilient drainage systems for new developments in both urban and rural areas”. This blogpost will look at what sustainable drainage is, and how it has developed in Wales (including the proposed new legislation), and what it has achieved so far.

What are sustainable drainage systems?

SuDS are designed to reduce the impact of development on surface water drainage by working with natural processes to drain away surface water run-off. This is done by collecting, storing, and cleaning water before allowing it to be released slowly back into the environment.

The SuDS approach is different from conventional drainage systems which are based on underground pipes to move rainwater away from properties as quickly as possible. Conventional systems can contribute to increased risk of flooding, pollution and groundwater contamination.

The benefits of SuDS include reducing the amount of water contaminated with sewage that is pumped for treatment, and reducing the risk of overflows and flooding. Depending on how they are designed, SuDS can also improve urban design quality, create public green space, increase biodiversity, and improve air quality and noise buffering.

You can read more about SuDS on the SuDS Wales website.

Development of SuDs in Wales

The Welsh Government’s approach to SuDS is set out in its Water Strategy for Wales. This strategy sets out the plan for interim, non-statutory standards for sustainable drainage (SuDS), published on an advisory basis so that the relevant parties (designers, developers, local authorities etc) can demonstrate that they have taken account of the Welsh Government’s policy on Development and Flood Risk and Nature Conservation and Planning.

These interim standards, published in December 2015, also served as a pilot scheme, so if necessary they could be revised ahead of any statutory orders made by Welsh Ministers. Details of what the interim standards cover is discussed in a previous blogpost.

New Legislation

The Welsh Government are making SuDS mandatory on new developments by bringing forward a suite of new statutory instruments, made under Schedule 3 to the Flood and Water Management Act 2010,. The Welsh Government say these:

…will help deliver our commitment to improve management of our water environment. It also supports our targets for new developments whilst delivering ecosystem resilience, enhanced biodiversity and benefits for citizens across Well-being Goals and ‘Prosperity for All’ priorities.

The commencement order made by the Welsh Government means that the legislation will come into force on 7 January 2019. Meaning that from this date:

All new developments of more than 1 house or where the construction area is 100m2 or more, will require sustainable drainage systems (SuDS) for managing surface water;
Drainage systems for all new developments must be designed and built in accordance with statutory SuDS standards;
Local authorities will become the SuDS Approving Body (SAB); and
SuDS schemes must be approved by the local authority acting in its SAB role before construction work begins. The SAB will have a duty to adopt compliant SuDS so long as it is built and functions in accordance with the approved proposals, including any SAB conditions of approval.

Examples of SuDs in Wales

Greener Grangetown

The Greener Grangetown scheme is a partnership between Cardiff City Council, Dŵr Cymru and Natural Resources Wales (NRW). The scheme uses SuDS techniques to collect, clean and divert rainwater directly into the River Taff, instead of pumping it eight miles through the Vale of Glamorgan to the sea as was currently the case. The scheme included planted areas that to help absorb rainwater, increase biodiversity and provide public green space.

NRW has produced a Greener Grangetown Video:

The Greener Grangetown project has now completed and resulted in:

  • 42,480m² of surface water being removed from the combined waste water network (the equivalent of 10 football pitches);
  • An additional 1,600m² of green space (the equivalent of 4 basketball courts);
  • The creation of Wales’ first ever ‘bicycle street’ along one of the busiest sections of the Taff Trail Active Travel route, slowing traffic by design and improving conditions for pedestrians and cyclists;
  • Increased biodiversity – 135 new trees and thousands of shrubs and grasses planted;
  • Creation of a community orchard;
  • 26 new cycle stands;
  • 12 new litter bins;
  • 9 new seats and benches; and
  • Increased resident-only parking spaces.

RainScape, Llanelli

Dŵr Cymru is investing around £80million in a number of RainScape projects in Wales up to 2020. Projects in Llanelli have been developed to address issues with the volume of rainwater entering sewers during periods of heavy rainfall. One project involved dealing with surface water issues in a primary school by introducing a pond, a swale, planters, permeable paving, water butts and an outdoor educational area.

You can read more about Dŵr Cymru’s projects on its RainScape website.

Article by Lorna Scurlock, National Assembly for Wales Research Service