New Build Estate and Flood Risk

Stefano123

I am currently in the process of buying a new home on a new build estate, and I recently received my flood risk assessment which has come back as high risk. However, I have noticed that my next-door neighbor's property shows no risk at all. I am puzzled and concerned about this discrepancy and was wondering if anyone could shed some light on why this might be the case. Perhaps its because its so new (built in 2022) that the maps haven't been updated?

Perhaps there are differences in the topography of the land, the drainage systems or the elevation of the properties that could account for this difference in flood risk. It could also be worth checking with the relevant authorities or the builder of the estate to see if they can provide any additional information or clarification on this matter.

I would greatly appreciate any insights or advice that you may have on this issue. Thank you in advance for your help!

Linton

You should not take the flood risk figures at their face value.  As an example I am in a medium risk flood risk area.  The reason is that some 25 miles away there is a large modern reservoir.  Should the dam collapse the resulting load on the local river could possibly flood the house.  So understand what the risk really is, visit the area, and talk to the locals. They will know if the site always was rather wet or there hasnt been a problem in living memory.

In your case perhaps the new estate could have been built on low-lying or marshy ground which has been raised or protected in some other way.

The only real possible practical problem is house insurance.  In our case some companies charged extra than otherwise, others weren't bothered at all.  I believe that insurance companies will have their own data rather than rely on the published maps.

Stefano123

Thanks for the advice. Really appreciate it.

I am aware that the developer has taken significant precautions and I have knocked on the doors of others on the estate and they do tell me a car park flooded at the lowest point in the area half a mile away but there's no issue in the few years the estates been there. So while there does seem to be some localised flooding, and some risk, it's baffling why my house would be classed as "high" risk, my back garden has "no risk" and next door is also "no risk". Home insurance doesn't seem to be abnormally high either. I'm pretty thorough though so just seeing if anyone has inside knowledge of how these maps are calculated. 

user1977

Have you looked at the planning papers on the council's website? They'll include much more detailed and useful flood risk assessments carried out by the developers, which will have taken account of what they're planning to build.

The trouble with getting your own flood risk assessment is that it'll probably just tell you how likely e.g. Farmer Giles' field (or whatever the site used to be) is to flood, which isn't necessarily much use.

DairyQueen

We own property rated 'high risk' on the EA site because of its proximity to a flood plain. However, when viewing the map in a larger scale it becomes obvious that our property sits in zone 2 (medium risk) whilst our immediate neighbour is zone 3 (high risk). The difference? The topography of the land. The properties are on a slope and we are approx 0.5 metres higher.

Our property hasn't flooded in living memory. House insurance can be subject to flood weighting with some insurers, but no weighting with others. It pays to shop around.

The EA maps do many properties a disservice as flood risk is property specific and a correct assessment seems to be beyond the capability of the EA's very general algorithms.

Stefano123

user1977 said:

Have you looked at the planning papers on the council's website? They'll include much more detailed and useful flood risk assessments carried out by the developers, which will have taken account of what they're planning to build.

The trouble with getting your own flood risk assessment is that it'll probably just tell you how likely e.g. Farmer Giles' field (or whatever the site used to be) is to flood, which isn't necessarily much use.

I have had a look at the planning application and there seems to have indeed been works done. I spoke to the ground works team too and they've told me there are 20inch pipes being laid (normally 9inch from what I'm aware) to carry the water away.

I was just really seeking to understand if my hunch was right that the mapping is based on when it was Farmer Giles' field.

I guess, I'm satisfied enough, to go ahead with the purchase, but it would be nice for resale just to have covered all bases to have a document which supports the fact that things have indeed changes since Farmer Giles owned the field.    

Stefano123

DairyQueen said:

We own property rated 'high risk' on the EA site because of its proximity to a flood plain. However, when viewing the map in a larger scale it becomes obvious that our property sits in zone 2 (medium risk) whilst our immediate neighbour is zone 3 (high risk). The difference? The topography of the land. The properties are on a slope and we are approx 0.5 metres higher.

Topographically, all the houses on the road are on exactly the same levels five or take a few centimetres so that's why I was baffled. 

daveyjp

A basic flood risk assessment will be little more than a search on the EA website.

The data is far too coarse and will take no account of any recent works on development sites to reduce flooding.

A development wouldn't be permitted in an area where flood risk was high until the applicant had shown either the EA data was too coarse and their site wouldn't flood, or they would carry out work which reduced the risk significantly.

The issue is the EA maps aren't updated regularly enough to take into account alleviation schemes provided by others.