The idea of a sustainable drainage system (SuDS) is to mimic, as closely as possible, natural drainage of a site in order to minimise the impact that urban developments have on flooding and pollution of rivers, streams and other water bodies. SuDS has become an essential component to any building development but the regulations around it can be confusing as they differ across the UK.
Why is sustainable drainage necessary?
Many surface water drains are operating close to full capacity, with the addition of new-builds these drainage systems need extra drainage capacity.
What are the benefits of SuDS?
Benefits of SuDS include:
- Flood risk management.
- Reduced pressure on drainage systems.
- Useful in both flood and drought conditions
- Improved water quality
- Increased biodiversity and ecology
- Increased well being of residents
- Enhanced opportunities for education and amenity
What is the law in England?
The UK government’s expectation is that sustainable drainage systems will be provided in new developments wherever this is ‘appropriate’. To this effect, local planning policies and decisions on planning applications relating to major development will make sure that sustainable drainage systems for the management of run-off are put in place, unless demonstrated to be inappropriate.
The current requirement in national policy is that all new developments in areas at risk of flooding should give priority to the use of a sustainable drainage system - this will continue to apply. Through the planning conditions or planning obligations, there should be clear arrangements in place for ongoing maintenance for the SuDS over the lifetime of the development to ensure that they are working how they should be.
Paragraphs 163 & 165 of the National Planning Policy Framework (NPPF)* support the applications of SuDS among other flood risk and water quality related matters. This section of the NPPF says that when determining any planning applications, local planning authorities should ensure that flood risk is not increased elsewhere when developing sites. Development in hush risk flooding areas will only be allowed if they are shown to incorporate a sustainable drainage system.
The system used should:
- Take account of advice from the lead local flood authority
- Have appropriate proposed minimum operational standards
- Have maintenance arrangements in place to ensure an acceptable standard of operation for the lifetime of the development
- Where possible, provide multifunctional benefits.
The Planning Practice Guidelines** note that “sustainable drainage systems are designed to control surface water run-off close to where it falls and mimic natural drainage as closely as possible”.
The guidelines say that they such systems provide opportunities to:
- Reduce the causes and impacts of flooding
- Remove pollutants from urban run-off at source
- Combine water management with green space with benefits for amenity, recreation and wildlife”.
What is the law in Wales?
In 2019 Wales made developments in Wales of more than one dwelling, or with a construction area of 100 square metres or more, to include Sustainable Drainage Systems (SuDS), according to the SuDS Statutory Guidance***. Approval from the local authority’s SuDS Approving Body (SAB) is required, alongside planning approval, before construction work begins. Local development plans and local flood risk management strategies will outline requirements for SuDS, and if formally adopted these are enforceable through the planning process. These will vary from local authority to local authority.
What is the law in Scotland?
In Scotland, SuDS are a legal requirement for all developments except single dwellings that drain to the water environment unless they discharge to coastal waters.
How can we help you?
If you need a SuDS system we can help you with our range of drainage solutions - such as soakaway crates, attenuation pipes, stormwater attenuation tanks, lagoons and flow control units where required. Please give one our experts a call to discuss the best solution for you on 0121 351 3230.