Planning approval often depends on SuDS as without it the surface water networks and rivers would overflow, cause flooding, affecting people’s homes and livelihoods.

Local Planning Authorities are increasingly asking developers to show how they’ll manage surface water run-off at their site, at planning application stage, due to there being an increase in flood risk through the use of ‘hard engineered’ traditional drainage systems and the impacts of climate change.

A more effective and sustainable approach to surface water is required, in the form of SuDS (Sustainable Urban Drainage Systems). SuDS strategies are key to the successful management of both the existing and future risk of flooding.

In this article, we will discuss why proposed developments often require SuDS design and strategy as part of their Planning Applications.

Why are SuDS Important?

Sustainable drainage systems aim to mimic natural drainage by replicating similar processes and aiming to deal with its surface water runoff at source via infiltration, where possible. This, therefore, reduces the pressure on traditional piped drainage and decreases the risk of flash flooding in the local area, by reducing the peak flow rate of surface water runoff entering the pipes and watercourses and rivers.

SuDS strategies are better for the environment, reduce water pollution and flood damage, and also contribute to improving wildlife and biodiversity in urban landscapes.

Nimbus Engineering SuDS Reports

What Do Developers Need to Know About SuDS?

In 2015, the National Planning Policy was revised to include that all major new developments (over 10 units or 1000m2 for commercial developments) would require a SuDS strategy to be submitted with the planning application. However, some LLFA’s (Lead Local Flooding Authorities) are now asking for SuDS reports for much smaller schemes as a part of the planning application process. This could be due to the proposed development site being in a critical drainage area (CDA) or just a requirement by the particular LLFA. The level of detail required by each LLFA can vary, however as we work on projects UK wide, we are well versed in the requirements of each particular LLFA.

The most common situation for when a SuDS assessment is required is when a local authority has included a planning condition referencing drainage. However, if adequate provision is not made for SuDS at the planning application stage and the developer/builder is not aware of the requirements, then it can be difficult to fit SuDS in once the site layout has been confirmed, therefore this requirement at planning application stage allows the various stakeholders to be made of the requirements at the early stages of a development, and allow them to design the site in order to be able to provide these SuDS systems by following the SuDS hierarchy, easily and at a lower cost.

Finally, when it comes to SuDS strategies and assessments, time is crucial. The earlier SuDS are considered in the development process, the lower the overall costs and the higher the probability that SuDS implementation will be achievable.


SuDS (Sustainable Urban Drainage Systems) can assist new development to be undertaken in urban areas where the existing sewers are at or close to capacity, and therefore planning committees would be less likely to object to the development proposals.

SuDS is a natural and sustainable approach for modern developments to integrate into their site, minimise the risk of flooding, providing amenity value and increasing biodiversity at the site, whilst also increasing their chances of achieving planning permission.

Nimbus Engineering SuDS Reports

Choose Nimbus for your SuDS Design

As Civil Engineering and Environmental consultants, we can give you early-stage advice for Sustainable Urban Drainage Systems (SuDS) designs to integrate into your development, allowing you to work around any constraints or risks, in a natural and ecological way.

Nimbus can provide you with SuDS reports and assessments that will give you a sustainable drainage strategy, with the required level of detail, to minimise surface water run-off from your proposed development, helping you achieve planning application approval.

As we have good relationships with the Local Planning Authorities and Lead Local Flooding Authorities and are versed with the requirements of each due to experience of working on sites nationwide, we can help you achieve planning approval and ensure that our reports and design are robust and cost-effective also. Talk to us today!

Sadia Luckett

Written by Sadia Luckett

Sadia Luckett is the Director at Nimbus Engineering, specialising in foul and surface water drainage & SuDS.