Advice on buying a house with high surface water flood risk

[Ducksinwater]

A property we have viewed is very low risk for sea and river flooding but high risk for surface water. I am told the house has never flooded and the issue is actually with the road in front of the house. Any advice? I would want to know if it can be remedied in any way or if we would be stuck with a house that may flood! Some pointers on what to look at, what surveys can be completed etc would be really helpful.

Check out whether you can get insurance for it.

I'd make more enquiries beyond the overall government/EA risk warnings as they are not always particularly helpful or accurate.

Groundwater flooding is no joke though, so worth investigating including with insurance as PP said

Most definitely! I am just unclear on what other checks I can do. It would be helpful if a surveyor or expert could give us a report on what is causing the issue and how we can (if we can) remedy the issue.

It’ll be worth getting hold of one of the sewerage engineers from the local water company and seeing what they think. I used to do this job and knew every area/street in my patch where surface water flooding was a risk due to sewer capacity. They will probably have a modeller who works in the team who will be able to predict flooding based on a 1 in a 100 year storm, 1 in a 50 year storm, etc. only caveat is that 1 in a 100 year storms are becoming more common! But they may know about plans to upgrade sewerage capacity or the pumps at the local pumping station if that’s causing problems. There are certainly areas in my home town that I’d never buy a property in because of the risk of surface water flooding.

knock a couple of the neighbours door and ask how bad the flooding is?

round the corner from me floods so badly they have to get decanted and can no longer get flood insurance.

we are nowhere near rivers or the sea. it’s groundwater.

Ask your mortgage lender too - they may not lend with that risk.

Flooding is only going to get worse so I wouldn't touch a house that is already high risk of surface flooding.

I know someone who bought a house 2 years ago and it's flooded each winter. Insurance pays for them to stay in B&B but it takes months and months to get repaired. They've been in B&B since last November. Since they bought the house they've only managed to live in it for a couple of months before it's flooded again and it's likely to happen all over again this autumn. Obviously they can't sell it either, so stuck with it. Total misery.

My home changed from low to high risk of surface water flooding. I couldn't then get insurance that covered flood, I went with "Homeprotect" who specialise but ultimately they wouldn't cover food, mentioned something about "Flood Re" but my house was too new to qualify. I wrote to the council and environment agency about why I was at risk, what the causes would be, how I could protect my property. Got a limited response back which I didn't find helpful.

Interestingly I checked neighbouring properties and they all remain at low risk, including the one directly opposite my home! Go figure! Check the long term flood risk for an area in England - GOV.UK

I’d be very cautious with high risk unless there are clear and obvious mitigations. I live in an area where the whole town is low to medium risk due to an unusually high water table and a lot of hills. Some of our neighbours have had issues due to water running straight down the hill, and most have drains just before the house to mitigate. We’re on the corner so have a strategically placed wall (neighbours wouldn’t be able to access their driveways if the did this) to avoid this issue.

Can you get insurance on this house? What year was it built because for floodre it has to have been built pre 2009

Thanks all! Very helpful! There is only one neighbouring property and they are also very low for sea and river but high risk for surface water so I will ask them.

I need to see if someone could give a report on any possible mitigations as I suspect it’s neighbouring land that would cause the issues.

I don’t know, we haven’t even put an offer in yet as I want to know what mitigations could be put in place (if any) before offering on it. It’s never flooded (based on what the EA says).

It's tricky because surface water flooding from road run off is dependent on how well highway drainage is maintained. Which depends on amongst other things, how much funding the council has to allocate to it, and whether they have accurate maps of their subsurface drainage systems, which they often don't.

Theat means there may not be the data available to better model it, unlike fluvial (river) flooding where there are generally better records.

You can get something called a property level protection (PLP) survey which will make recommendations about things like removable door barriers, air brick covers, non-return valves for toilets. The trouble is you need some warning to get those in place. With fluvial flooding, the upstream river levels will normally give prior warning, but surface water flooding is typically rapid onset, so it's less help.

It’s never flooded (based on what the EA says).

But that doesn't mean it never will. Water companies have failed to reinvest for decades. They have not improved drainage, new homes are being built on land that used to soak up excess overflow (they're even building them on floodplains in some cases) and weather is changing. Flash flooding is more common which makes surface flooding so much worse.

This is another issue as the road is privately owned so it’s not as if I can just contact the Council either! I imagine the water is running off neighbouring fields but I’m no expert on this so would like an expert to report on it.

The trouble is, even an expert can't predict future weather patterns. Or predict whether future developments will affect drainage.

What's the point in spending the money on a report that will be full of legal caveats. Surely it's not worth the risk.

I'd just avoid it!

I get your point. I suppose, it doesn’t make sense to me that there are all these properties which are just going to rot away because nobody can/ will do anything to help mitigate the issue. It’s a very old cottage so it just seems a shame!

One of the questions insurance companies will ask is it it in a flood risk area, even if it’s never flooded and never will in your lifetime that will be enough for the to either not offer you insurance or offer a sky high premium.
I know this because I have just renewed our buildings insurance and that was one of the questions. We live rurally and very near a small river, it’s not a flood risk but we have major issues with insurance because of that river which is not a flood risk and has never flooded. Floodre can’t help because it was built after 2009 so we pay the extortionate insurance as we have no choice.
Id hate to imagine the situation if it was a high flood risk area. I just wouldn’t have bought the house.

If the road is privately owned then someone must be reponsible for it - a survey that understands why it’s a flood risk and what drainage could be added to mitigate , and how expensive that would be to install and maintain , all seems sensible

depends on who owns the road in that case

I would run a mile, flooding is going to get worse

I wouldn't go there OP. Global warming and extreme weather will only get worse.

to spin an ‘it might be ok’ angle -
EA Flood maps for planning (which I assume this is based on) are usually based on LIDAR data, which is a map of the ground levels taken from the air. A computer simulation of various rainfall events is then run, outputting the worst case flood extents for 1 in 30, 100, and 1000 year flood events (don’t get hung up on the numerical probability, but read up on this further to help your understanding).

The problem can be when relying on ground level data as seen from the sky, that underground features are not visible.

On a project I have recently worked on, there was a swale running along the edge of a park at the side of a road in a residential area. The swale goes through a culvert under a road, but the LIDAR cannot see this, so the model thinks the water is hitting a blockage and can’t flow any further, which on the flood map displays as ‘backing up’ and an increased depth of water to the upstream side of the culvert.

The area immediately upstream of the culvert shows as a 1 in 30 chance of flooding each year to a depth of 900-1200mm, but in reality there is no flooding here.
Having a look around the area, speaking to the neighbour, and having a look at the maps should help your understanding.

Obviously I have no idea of the case in this circumstance, but thought it may help to share.

https://flood-map-for-planning.service.gov.uk/

Actually fields are generally good as they will soak up water. What I would be vary wary of is if, at some point in the future, some developer decides they'd make a nice housing estate and builds on them. How likely this is probably depends where you are in the country.

We had that in our village.
A row of Victorian terraced houses that were slightly lower than the road. In a particularly heavy downpour (which overwhelmed the drains) the water would run across the path and straight under the front doors, through the hall and out the back.
Surface drainage channels were built along the path, low retaining walls etc but you could not stop it going down the steps.
It was noticeable that later houses (pre-war onwards) were at least level with the road.