Sustainable Drainage Systems (SuDS)

The Government announced last month that it would be making sustainable drainage systems (SuDS) mandatory for all new developments in England, as they implement Schedule 3 to the 2010 Flood and Water Management act. But what are SuDs and how do they benefit our waterways and reduce the risk of flooding?

Matthew Woodard


What are Sustainable Drainage Systems (SuDS)

Flooding is becoming an ever more prominent issue due to a combination of climate change and urban development. As more green spaces are built on and paved over, we lose areas of permeable land that can “soak up” rainwater. This often results in existing drainage systems being overloaded, causing flooding and other issues. Sustainable Drainage Systems act as a nature-based solution to a variety of these water-related problems and can mitigate the impacts of flooding, whilst also improving water quality, biodiversity, and even human health.

SuDs can take many forms, for example, rainwater harvesting. This simply involves installing a water butt which effectively reduces the flow of water and the volume that enters our sewers and waterways during heavy rainfall. Rainwater gardens are another option, whereby a shallow depression is created with absorbent soil and vegetation, increasing the amount of water entering the soil and reducing runoff. They also create brilliant habitats for wildlife.

Installing a water butt in your garden is a simple, yet effective way to implement SuDS.

Fundamentally, SuDS often involve replacing impermeable surfaces with those able to absorb water, from pavement to grass, green roofs are even an option! There are also middle grounds that include paving blocks with gaps to encourage rainwater to permeate the soil beneath.

What are the benefits?

SuDS come with a host of benefits from the obvious to the unexpected. By catching and storing surplus water, they act to reduce localised flooding. As a result, they can also mitigate the impacts of drought. Increased water levels in the soil help habitats to tolerate periods of low rainfall, and systems such as water butts enable people to have access to water even during times of reduced rainfall.

Water quality is also positively impacted by the presence of SuDS. They act as filters, removing sediment and contaminants from the water, thereby preventing them from reaching our waterways. Water runoff from paved areas can contain heavy metals, microplastics, and oils from vehicles. Reducing the levels of such contaminants is beneficial to aquatic life, the environment, and can reduce the need for treating the water.

Beyond the improvement to water quality, the implementation of SuDS is beneficial to wider biodiversity and ecology. Due to being a nature-based solution, their creation provides a variety of habitats that can support a plethora of flora and fauna. Increased green spaces throughout urban environments creates links to other habitats, resulting in a network that can support both existing and new wildlife.

Additionally, the increase in green spaces is beneficial to human health. Research continues to show the benefit of green and blue spaces on mental health. Interspersing urban areas with SuDScan help the overall wellbeing of communities.

On top of it all, SuDS can improve our climate resilience. The vegetation involved in the various systems can capture and store carbon, as well as greenhouses gases, thereby improving air quality. Added green spaces in urban areas can also help regulate building temperature.

What does the announcement mean?

The January announcement from the UK government states that they will implement Schedule 3 to the 2010 Flood and Water Management Act. This means that sustainable drainage systems will be mandatory for all new developments in England. The mandates are set to come into effect in 2024, in the lead up to that time, DEFRA intend to assess any potential burdens on developers, how these should be managed, and improving SuDS-related skills. This is certainly a welcome change and given the recent droughts and flooding, solutions are certainly needed. Utilising nature-based solutions to combat these problems and improve our resilience to climate change, and the associated weather, is ideal as they often come with a variety of further benefits, beyond their main intention.

We are interested to see how these mandates impact the presence and use of SuDS and we hope to see them become more commonly implemented.

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