Using SuDS to Reduce Nitrogen

Friday 01 March 2024

For developers, tackling the challenges of 'Nutrient Neutrality' can be crucial. These challenges can add an additional layer of complexity to critical projects, underscoring the delicate balance between sustainable development and the natural environment.

Recent guidance from the Construction Industry Research and Information Association (CIRIA) in October 2023 offers valuable insights. Their publication titled "Using SuDS to reduce nitrogen in surface water runoff (C815F)" illuminates the role of Sustainable Drainage Systems (SuDS) in mitigating nitrogen levels in surface water runoff.

What are SuDS?

SuDS, short for Sustainable Drainage Systems, are innovative approaches that mimic natural drainage processes. They manage rainfall close to where it falls, promoting biodiversity, flood risk management, and water quality. SuDS create vibrant, sustainable communities by harmonizing development with nature.

Why is Nutrient Neutrality Important?

Nutrient neutrality requires that new development in certain areas should not exacerbate 'nutrient pollution' in water catchments. This approach aims to safeguard fragile ecosystems already burdened by nutrient pollution.

The issues surrounding nutrient neutrality can add an additional layer of complexity to projects. However, it is crucial to ensure that while advancing these projects, we don't compound environmental degradation in our water bodies.

Using SuDS to Reduce Nitrogen

SuDS offer a multifaceted solution to mitigate nitrogen runoff. These systems are often organised into SuDS management trains, which are classes of drainage features designed to treat runoff in a step-by-step process. These trains incorporate both 'dry' devices and SuDS featuring permanent water.

Dry Devices: These facilitate nitrogen infiltration through soil horizons. Examples include permeable pavements and infiltration trenches. They allow water to percolate through the soil, removing pollutants like nitrogen in the process.

SuDS with Permanent Water: These include retention ponds or wetlands, fostering sedimentation and the growth of anaerobic microorganisms. These features provide a habitat for microbes that can break down nitrogen compounds, reducing their concentration in the water.

By incorporating a combination of these features into SuDS management trains, nitrogen pollution from a range of sources can be effectively captured and treated, contributing to improved water quality and environmental health.


Staying abreast of evolving guidance is imperative for navigating the challenges posed by nutrient neutrality zones. By integrating SuDS into housing developments, we can strike a balance between growth and preservation of the natural environment.

In conclusion, SuDS continue to provide opportunities for sustainable development. By embracing these innovative drainage solutions, we can meet housing demands while safeguarding our precious ecosystems. Let's build a future where development and the environment can thrive together. For further discussions or enquiries, please reach out to PFA Consulting’s Flood Risk & Water Management team. Together, let's pave the way for sustainable, nutrient-neutral communities.