What is a Flood Risk Assessment and Do I Need One?

What is a Flood Risk Assessment and Do I Need One?

If you are a developer of any kind, then you need to know about Flood Risk Assessments. Even if you are building you own home on any bit of land over 1 hectare or 2.47 acres or if it is within a flood zone you will fall under the remit of a developer and need an FRA.

What is a Flood Risk Assessment?

A flood risk assessment or FRA is a report that on a basic level simply outlines the flood risks to any given development site. It also gives recommendations for flood mitigation strategies that could reduce the impact of flooding to the site and, of course, the surrounding area. In short, it’s a very technical report that planning authorities need to see before approving a site for development. If the proposed development is likely to flood or to cause flooding then it will not be allowed to go ahead without a clear and actionable plan to mitigate and heavily reduce the impact of the development itself in terms of flooding.

Where Do I Get a Flood Risk Assessment?

Most large developers will already work with a chosen flood risk consultant but for those new to development or building their own property there are a range of companies out there. However, it is vital the company is professional and experienced. A badly put together FRA could at best simply fail to win over the planning authorities but at worst could lead to flooding, damage, insurance claims and legal action of issues arise post build. The ley is to find an experience and recommended flood risk consultant or civil engineering firm that has the know how and experience of your location as well as the local planning authorities and how they work.

How Do I Know if I need an FRA?

As mentioned above if the development is over 1 hectare then legally you will need an FRA. However, even if the proposed development is smaller you will still need one if you are in a flood zone. To find out if the development is in a flood zone simply go here – https://flood-map-for-planning.service.gov.uk/ and put in the postcode. This is a very handy tool provided by the Environment Agency to give you a quick and simple answer.

Simply being in a flood zone doesn’t mean planning will not be granted, it is important not to think the worst in this case. As much as flooding is critical It is becoming more and more common and it is, in fact, mitigation of the flooding that is becoming more important than the risk itself.

What is a Drainage Strategy?

It a common to not only need a Flood Risk Assessment but as a result of the report also be asked to produce a drainage strategy. Why is drainage an issue and why does it need a strategy? Is the FRA suggests a high risk of flooding then the planning authorities will want to see a detailed strategy to deal with excess surface and flood water. A detail drainage strategy will do just that. It will show how the flood water will be managed not only with the development in question in mind but also land, property and the areas surrounding the development. Flooding of a new development is certainly an issue but if that development actually changes the drainage of existing land it can cause flooding in other areas that were not at risk before.


You may hear this term when researching drainage and flood risk assessment. It mean Sustainable Drainage Systems it once included the work “urban” but this has been removed. It basically describes flood mitigation and drainage plans that can emulate and mimic natural drainage and run off. The idea is to design ditches and the like to temporarily hold water and allow it to drain and soak onto the ground slowly thus preventing flooding.

So, Flood Risk is Important?

Well, yes, yes it is. With flooding becoming more and more of an issue the government are quite rightly holding developers to account in regards to creating flood friendly buildings. One of the biggest causes of flooding is the way in which we have changed the physical environment. By building car parks, and housing on land that would once have absorbed water we increase the effect of flooding. While it is fair to say climate change is increasing the likely hood of high rain fall it is also fair to say it is the way we have created the built environment that is magnifying the issue.