We was told this.
We checked the potential source of the groundwater flood.
It was 450 metres DOWNHILL from our house and in no way ever going to affect our property. Our house is at the top of a considerable hill and some considerable metres above sea level (which was one of the reasons we were keen on it anyway)
We thought it was some hilarious joke. Would our solitictors question it? Nope they didnt. Right pain in the arse it was too.
We had to establish what we had to do for insurance purposes. (Basically we ignored it after advice elsewhere because it was so farcical)
Everyone we spoke to about this, who knows where our house is has fallen about laughing and thought we were kidding. Including friends who have had family live in the vicinity of our house for the last 400 years or so.
To put it bluntly, if we have a groundwater flooding issue, then its not a 1 in 100 year event. There is no historical record of anything like that occurring.
Its would major disaster the size of which has not been seen in the uk in at least the last 1000 years (you are probably looking at several hundred thousand years tbh) which would affect most of the NW of England. At which point we figure we've got bigger problems than worrying about whether our house has flooded. Namely anarchy, disease, starvation and millions of people in this country dead and homeless.
And no im not exaggerating or being melodramatic. That just how bad this report was in way it was trying to suggest. I'm fairly confident that water still goes down hill and that even with climate change we aren't likely to see that much of an increase in rainfall. And I'm willing to bet my house on it. Quite literally.
My point is that what we found was these surveys are incredibly crude. To the point of being worse than useless for a lot of people because they don't necessarily look at the topography of the land and just do a 500m radius as the crow flies from the water source. Imho and in our experience its just some company doing a report making money out of utter bollocks and solitictors are only too happy to get on board with their cut too.
For us to have a raging torrent of water reach us from a source more than 15 vertical metres below the height of our house theres going to be some biblical event on.
We are far more at risk of surface water flooding, but even then we are still close enough to the top of the hill for it not to be a huge issue.
My advice would be to actually check maps of where this ground water is supposed to come from if you are worried. This can be done (though i forget how - our friend who lives 20 seconds around the corner was gobsmacked and found it on google as naturally they were a little concerned it didn't come up on their survey - turns out they are 50ms further away from the source so are apparently 'safe').
Then apply some common sense and a tiny bit of moderate intelligence.
I can't say i've lost sleep worrying about Noah's Ark floating past my house since we've moved in.