What Is a Sustainable Drainage System?

SuDS, which stands for Sustainable Drainage Systems, are becoming increasingly popular. That’s why this month at Express Drainage Surveys, we want to take time to explain what they are, how they mimic natural drainage to manage rainfall carefully and what’s driving their increasingly pivotal role for properties across the UK.

In this guide, you’ll learn all about the types of SuDS – source, site and regional controls – how they work and the way that some other techniques can help to address runoff. We’ll also touch upon the key benefits, including a reduction in flooding and pollution risks while enhancing biodiversity. Finally, we’ll also explore UK legislation and how these systems are designed and maintained.

A definition: What is a sustainable drainage system?

SuDS are a neutral and environmentally sensitive way to deal with surface water runoff for any development, but specifically around highly developed areas. The core principle of this approach is to slow, store and treat the water, rather than simply trying to discharge it somewhere immediately.

There are three general types of sustainable drainage systems applied here in the UK. The first is source control measures. These help to handle runoff and rainwater close to where it’s falling on the surface.

Secondly, there are site control measures. These are designed to tackle runoff from bigger areas, such as whole housing development sites, retail parks and some major road infrastructure.

Finally, we get to regional control measures. These are further along in the chain of source and site measures, gathering water from much bigger areas. Dealt with using the same principle of slowing, storing and treating, they simply operate on a larger scale in terms of sheer volume.

How SuDS work

How do sustainable drainage systems work? Here, we take a look at each control type:

Source-level techniques
- Green roofs can reduce or even eliminate runoff while providing much-needed biodiversity opportunities.
- Permeable paving allows for water to filter through slowly, trapping pollutants and minimising the amount of pooling.
- Filter drains trap pollutants while allowing water to filter through and away.
Site-level techniques
- Swales are shallow vegetated channels, carrying runoff between structures for a slower flow.
- Basins, ponds and wetlands all store runoff, creating natural settlement and pollutant removal.
Regional-level implementation
- This is a much broader level of storage and conveyance, with the ability to handle cumulative runoff, often in an urban environment.

Each system is slightly different based on the material, approach and scale, but as you can see, they share the common goal of reducing pressure on sewer systems.

The benefits of SuDS

You might be wondering why there is so much talk about SuDS right now, so let’s take a look at the major benefits of sustainable drainage systems in the context of the UK:

Using SuDS helps to reduce the risk of flooding at peak times, as it eases pressure put on sewers in a massive downpour.
The natural filtration that most sustainable options provide – either because it’s built-in or is a happy accident – means less pollution entering the waterways.
Biodiversity and the addition of green urban spaces are yet another benefit, making our spaces better for us and wildlife.
Overall, sustainable drainage offers long-term resilience and development flexibility, helping to meet the challenges of population growth and changes in our climate.

What is the legal policy, regulation and best practice?

As a key part of how we now plan, build and manage developments across the country, it’s time to take a look at what you need to know in England and Wales when it comes to the laws and policies for SuDS. It all boils down to the responsible management of surface water and the reduction of flood risks.

Flood and Water Management Act 2010: This is the Act that shifted the thinking away from defence and towards risk management of flooding. Councils were made responsible for local flooding, encouraging SuDS to be the go-to solution for any new developments.
Flood Risk Regulations: This is the effort to bring the EU Floods Directive into law here in the UK. It required authorities to assess flood risks and prepare management plans against risks. The Environment Agency leads this nationally, while Local Flood Authorities handle the responsibility at a local level.
Planning and Development: As you might expect, delivery of sustainable drainage systems is now tied closely to planning. That’s from both the national and local levels, with drainage schemes designed to meet non-statutory standards.
Building Regulations and Codes: In addition to the planning side of things, Building Regulations – and the previous Code for Sustainable Homes – are used to support improved water management systems and more sustainable design principles overall. You can read more about Building Regulations Part H in one of our previous posts.

If you’re keen to implement sustainable drainage solutions for your property or development, you should seek the assistance of planning and design specialists to ensure you’re meeting the relevant standards.

Surveys and maintenance for SuDS

While SuDS are a positive addition to our infrastructure here in the UK, they should be designed with maintenance in mind. This means that it can be kept up to standard, always working, and you’re not then liable for any issues further down the line.

Certain sustainable drainage systems may require surveys to report on their condition, which is another aspect of maintenance to keep in mind when planning any such infrastructure. At Express Drainage Surveys, we can assist with CCTV drain surveys for certain sustainable drainage systems, allowing you to inspect their condition and pinpoint any issues.

Expert drainage services from a company you can trust

With no hidden charges, affordable packages and rapid response times, whenever you need drainage services, we’re the company to call upon. While we specialise in CCTV surveys, our accredited engineers provide a full range of services to meet your every need, including the following:

So, whether it’s trouble with a recurring blockage or if you need a survey to establish and map your current drainage system, we’re always on hand. Contact us today to discuss your exact requirements, and we’ll provide a free estimate.