Surface Water Flood Risk Concern for Property Purchase

Maka344

I am in the early stages of purchasing a property that is currently identified as being at high risk of surface water flooding on the EA's future flood risk map website. There are no rivers or seas nearby, and I understand that flood risk assessments are generally based on geographic and topographic data rather than the physical condition of the land (e.g., whether it is concreted or grassed).

The current owners have installed a full shingle driveway, ACO drains at the front of the property that drain into the main sewer, and a block lip at the top of the drive. They have confirmed that, in their seven years of ownership, they have not experienced any surface water flooding issues, even prior to these modifications.

I also reached out on the local community group, and a neighbor two doors down responded with: “They used to get surface water pooling on their drive but not since they’ve had the drainage and shingle drive installed.”

Additionally, a friend of mine, who is a senior insurance underwriter, checked the property on his system and confirmed that there are no recorded flood claims. He mentioned that they would not impose any special terms, and my insurance quote for buildings and contents came back at around £250. He did note that properties behind this one have experienced surface water issues at the bottom of their gardens due to a slope, but these houses are 300-400 feet away and the gardens are generally 100ft long. 

I have also commissioned Groundsure and Landmark Flood Risk reports, both of which have come back with a low risk of surface water flooding for the property. When I questioned Landmark about the discrepancy between their report and the Environment Agency’s map, which indicates a high risk, they responded as follows:

“The flood report that you have received contains the very latest data and was compiled today. These reports are highly granular and property-specific to ensure that lenders can rely on their content. Landmark is one of the largest suppliers of environmental data to the sector across the UK. You will also see references to JBA Risk Management, who provide insurability data. I can assure you there is nothing to gain by providing you with a report showing minimal risk, as Landmark would not stand to gain anything from it.”

Kent County Council’s "Flood Risk to Communities" document states: “The EA’s future flood risk checker should not be used to identify the flood risk to individual properties, and should only serve to give a more general indication of an area’s susceptibility to surface water flooding.” This aligns with the findings in the environmental reports. I spoke with the manager of the data company, who confirmed that the Environment Agency’s data is more general and should not be used for assessing surface water risk for individual properties. He also mentioned that the data is due for a significant update in early 2025, and he suspects that the risk classification for the property will be downgraded based on the more precise data in the report.

Given all of this information, how concerned should I be about the surface water risk for this property? This is the biggest purchase of our lives, and I want to ensure that I have an accurate understanding of the flood risk. Thank you for any advice or insights you can provide.

EA's Surface Water Map:

Landmark Report:

TheJP

My house has a high risk of surface flooding. My 2 year old enjoys jumping in the puddles when it floods. Id say there is no risk at all.

horsewithnoname

If you look at the map showing the areas, much of the country seems to be high risk —which they define as 3% so I really wouldn’t be too concerned. If your insurance quote hasn’t come up at an outrageous cost then you can be fairly confident it’s nothing to worry about. 

Linton

horsewithnoname said:

If you look at the map showing the areas, much of the country seems to be high risk —which they define as 3% so I really wouldn’t be too concerned. If your insurance quote hasn’t come up at an outrageous cost then you can be fairly confident it’s nothing to worry about. 

Exactly.

I am in an area of high surface water flood risk.  A bit of research showed essentially that if the dam of a large modern reservoir 20 miles away failed the water would flow down the local river and flood parts of my neighbourhood.  My insurers obviously did not care, and neither do I.

ian1246

One thing to note is the risk can be hugely impacted by what type of land is around the property & what people do with it.

An example: My ex-family home (sold during divorce) was high risk. It infact flooded in 2014 for the first time due to surface water (no nearby water courses). The cause? The farmer ploughed his field in a different direction, meaning all the water poured down the "valleys" straight towards the houses, overwhelming the small ditch & soil barrier which had stopped flooding for decades prior.

No issues since - the farmer went back to ploughing his fields the other way around!!!

Albermarle

It is a reasonably regular topic on the forum, so try searching for similar threads.
The answer usually is ‘nothing to worry about’

Maka344

Thanks all. Appreciate your replies. Although the general consensus is not to worry, coming around posts like this doesn't help. 

TheJP

Maka344 said:

Thanks all. Appreciate your replies. Although the general consensus is not to worry, coming around posts like this doesn't help. 

You don't know the details of that property, is it close to water. Going from the post this person is looking at pointing the finger at the surveyor, searches are carried out by your solicitor and they advise. Its up to you but my experience living in a high risk surface flood area is that you dont have anything to worry about.

ReadingTim

Given the reports screen shot above, I'd rank risk of flooding somewhere between 'plague of locusts' and 'alien invasion' on the likelihood scale.... 

MysteryMe

The one institution that will know for sure how high a flood risk it is, is an insurance company. If they are not loading your premiums due to flood risk, it means they haven't had claims submitted for flooding in the area.

Maka344

Response from the Environment Agency, this could help someone else searching in the future:

Thank you for your email.

We respond to requests under the Freedom of Information Act 2000 and Environmental Information Regulations 2004.

Surface Water Flooding

Managing the risk of flooding from surface water (including mapping risk areas) is the responsibility of the Lead Local Flood Authority (LLFA), which in this instance is Kent County Council.

As part of Environment Agency’s (EA) strategic overview role and to support the country in meeting its legal obligations under the Flood Risk Regulations, the Environment Agency (EA) produced the Risk of Flooding from Surface Water (RoFSW) map in 2013. This allowed for a nationally consistent map to be produced.

The EA maintains the map, in so far as we collate LLFA local modelling outputs and periodically use these outputs to publish updates to the map via the GOV.UK website.  This is to ensure that there is consistency in the data (extent, depth, velocity, hazard, flow direction etc.) available across the country, however it is up to LLFAs as to where and when to carry out detailed local surface water modelling and whether that modelling should also be included in the national map.

An improved and updated new national map is in progress and is expected to be published in the early 2025.  This new national map is expected to be supplemented with local detailed modelling from LLFAs where appropriate and available.

If you disagrees with the map the first thing to do is to engage with your LLFA (Kent County Council) flood@kent.gov.uk . They might have extra information (such as local modelling or other evidence) which could support your case. If they agree the map in the investigated location is incorrect they might be able to re-model the area (which is a requirement to be able to change the map) or might  support your  claim by instructing us to add a short message to the website to inform about any potential anomalies and/or to point in a direction of where more information on local surface water flood risk is held. 

To change the map, we require a like for like modelling outputs. These can be produced/approved locally by the LLFA or nationally by the Environment Agency. The national updates are infrequent, however there is one planned for later this year with map publish date currently set for early 2025. This is likely to change our understanding of surface water risk locally due to changes in land use, catchment topography, modelling methodology and finally changes to the products published on the Check Your Long Term Flood Risk (CYLTFR) website. The changes are planned to be introduced in the early 2025. This is likely to change the risk result showing on CYLTFR website for the area around the property you query.

I wonder if I could take this opportunity to add an often-overlooked context about map and risk classification information shown on Check Your Long Term Flood Risk website.

MAP & RISK CLASSIFICATION

The ROFSW Map is intended to identify areas at risk of flooding from surface water and is not intended, nor suitable for identifying individual properties at risk of surface water flooding. Therefore, service refers to an “area around” a property, rather than a property itself, when indicating risk.

We have made changes to the service recently to reiterate almost at every stage that the results aren’t property specific. We continue to review and make improvements to the service based on customer feedback and analysis of how the service is used.

The reason for the website returning high surface water risk classification for the area around this property is that the address property point is within the 15m radius of the high risk (3.3% AEP – annual exceedance probability) extent. The system is designed to search for and return the highest risk within 15m radius of a defined property point (using the address point database). We now specifically reference the 15m search used for surface water, to flag that the risk refers to the area around the property. This (15m radius) was set to address one of the limitations of the mapping: by the nature of the modelling, often the maps show flooding only adjacent to a property, where unfortunately the property itself is at risk of internal flooding.

Please refer to the Open Government Licence which explains the permitted use of this information.

Kind regards

Flood & Coastal Risk Management Officer | Partnership & Strategic Overview (West Kent)

Environment Agency