What are SuDS and SuDS retrofitting?

Friday 16 February 2024

At PFA, we talk a lot about the importance of SuDS so we thought it was about time we sat down and comprehensively went through what SuDS are, why SuDS are important, what SuDS retrofitting is, why SuDS retrofitting is important and finally - what’s next for SuDS?

What are SuDS and why are SuDS important?

SuDS stands for SustainableDrainageSystems and according to susdrain: “SuDS (or Sustainable Drainage Systems) are an approach to managing rainfall in development that replicates natural drainage. Where possible managing rainfall close to where it falls and on, or near the surface.” Susdrain also explains that “SuDS help to manage flood risk and water quality and also improve biodiversity and amenity as well as a host of other benefits to create great places to live, work and play.”

Commonly used SuDS features include:

  • Green roofs

  • Infiltration Systems such as Soakaways

  • Rain Gardens

  • Pervious Paving

  • Swales

  • Wetlands

  • Detention Basins

  • And many more
















At PFA, we see SuDS as an important aspect of water management for many reasons, such as:

  • Reducing the reliance on traditional drainage systems

  • Helping to mitigate flood risk

  • Assisting clients in achieving their sustainable development goals

  • And more

Retrofitting SuDS – What are SuDS Retrofits and why are they important?

Retrofitting SuDS (sometimes referred to as SuDS retrofit) does what it says on the tin! CIRIA (the Construction Industry Research and Information Association) explains that: “SuDS retrofits are a cost-realistic means of climate change adaptation for surface water drainage in established urban areas. They are also a cost-effective means of addressing combined sewer overflows – a major issue for water companies. It is important that they are urgently progressed.”

Retrofitting SuDS is important because it:

  • Helps to alleviate the pressure placed on traditional drainage systems

  • Enhances Urban Resilience by integrating sustainable drainage features into existing urban landscapes and creating a more harmonious relationship between our built environment and nature

  • Increases biodiversity

  • Unlike traditional drainage systems that rapidly remove water through pipes, mimics nature, allowing rainwater to be handled more sustainably

What’s next for SuDS?

Although it looks likely that the implementation of Schedule 3 of the Flood Water Management Act will be delayed again, it is still important that the development sector follows its aims. Properly designed SuDS will “help address the impacts of climate change, urbanisation and increasing population while achieving multiple benefits such as reducing surface water flood risk, improving water quality, and harvesting rainwater to meet current and future needs.” (Source)

“Current planning policy requires that SuDS are included in all new major developments (developments over 10 homes), unless there is clear evidence that this would be inappropriate. This is in addition to requirements that SuDS should be given priority in new developments in flood risk areas.” (Source)

Wales implemented Schedule 3 of the Flood Water Management Act in 2019 and the Welsh Government has recently published the findings from its Post Implementation Review.

We believe that, as the understanding and use of SuDS increases, so too will the opportunities to integrate natural processes into the urban landscape.


To conclude, as urbanisation continues, SuDS create resilient, sustainable, and aesthetically pleasing urban spaces. From reducing flooding to improving water quality and enhancing biodiversity, SuDS and SuDS retrofit contribute to a healthier and more environmentally conscious urban future. We at PFA look forward to the increased implementation of SuDS and SuDS retrofit.

If you need help with SuDS, SuDS retrofit or any other Flood Risk and Water Management matters, contact PFA Consulting Ltd to access our wealth of knowledge in this field: