aegaea are experts in flood risk, water and environment, specialising in flood risk assessments, surface water drainage strategies and flood modelling. Our expertise is helping you unlock the development potential of your site, no matter what the size – from house extensions to 5000+ units, Aegaea works alongside you every step of the way.

Desire to build within a London borough has increased over the past decade. However, much of London is within a Critical Drainage Area and therefore legislation can be more complex than other areas of the UK.

​Our Flood Risk Team have years of experience dealing with London based Flood Authorities and the intricacies of London flood policy, giving us a unique insight to help you gain planning permission in London – from rear extensions to major applications, we’ve worked on them all!

Aegaea hold all the flood models and breach data on our own systems, so there’s no delay in your application while waiting for data – we can process and write your FRA within 5 working days! That’s time saving and cost saving across London.

Scroll down to find out more about our service, our experts, find out more about London FRAs, read our frequently asked questions, send us an enquiry, or submit your drawings and files.

We’ve worked on thousands of flood risk assessments. While the policy isn’t unique, we know that every development is. It’s your development, its personal, and it needs an expert that understands the nuance and details that make a successful FRA for planning.

Every quote from aegaea is free, unique and bespoke to your requirements, it’s just one of the ways that we set ourselves apart.

​Our expert consultants take the time to understand what you need and when you need it – delivering high quality, professional reports that have helped hundreds of customers obtain planning permission – all reviewed and signed off by Chartered professionals from CIWEM.

From a kitchen extension in London, to new build developments, experience the difference of working with aegaea and drop an email, form or call to our experts.

Different Types of Flood Risk in London

The City of London has been constructed on a large Flood Plain. As such the vast majority of it is within a Flood Zone. Central London in particular is affected by multiple sources of flooding. Thankfully, it’s also protected to a 1 in 1000-year standard of protection by the Thames Barrier. Without it, London would be at a much more significant risk of flooding.

The Environment Agency map for planning demonstrates only the flood risk from rivers and seas without the presence of defences. This is why Central London, such as the London Borough of Southwark for example, is shown to be within a Flood Zone. Due to its urban characteristics, London is greatly affected by surface water flooding and sewer flooding. However, these data sets cannot be accessed by the Environment Agency Flood Map for Planning.

There’s also the question of residual risk should the defences fail. Although this is considered to be a highly unlikely scenario, much of London is still assessed based on this risk. However small the possibility, the results of such an event would be devastating to much of the area.

When assessing flood risk throughout London, our team will review multiple sources of flooding, as well as this residual risk (commonly referred to as Breach), to ensure every risk can be mitigated to gain planning.

London also contains many boroughs that are considered Critical Drainage Areas. This is where surface water is unable to drain at an appropriate rate, causing further flooding. These areas always require a Flood Risk Assessment no matter the development.

Across London, the severity and extent of each source of flooding vary. It is therefore important for the success of a project to understand what flood zone your site is located in and whether it is affected by other sources of flooding. This could impact the design, timeframes, and mitigation measures required to make the development acceptable for planning. If each flood risk source has not been appropriately reviewed, it is likely to be rejected at Planning by the Environment Agency or Local Planning Authority.

There are certain developments that are permitted within the London Flood Zones that don’t need an exception test. However, if it is necessary and the development doesn’t pass the exception test, it’s likely to be rejected at the planning stage.

Find out more about the exception test here.

Does London Development have to adhere to National Planning Policy?