Ampthill has almost no flood risk from rivers or the sea, but surface water is a real risk on a minority of streets. None of its postcodes are in a river flood zone. About one in ten is rated high on at least one flood measure. No flooding is on record. The risk comes from rain that has nowhere to drain.
On the Environment Agency's river-and-sea mapping, 0% of Ampthill's postcodes are in Flood Zone 3, the highest-probability band, and 0% are in Flood Zone 2, the medium-probability band that lies beyond it. On the question most buyers ask first, the answer is nothing.
Surface water is where the risk lies. Heavy rain collects in dips, on roads and behind walls whether or not there is a river nearby, and it is mapped separately from river flooding. That is why a town with empty flood zones can still have streets with a flood problem.
The Environment Agency's climate-adjusted river-and-sea zone also covers 0% of Ampthill's postcodes, so on that measure the outlook for river flooding stays where it is now. The climate figure covers rivers and sea only. It says nothing about how much more rain the drains will have to cope with.
For insurance, the clean river-and-sea record helps, and insurers will see it. They also price surface-water risk, sometimes for each individual address, so a home on a high-rated street can cost more to insure than its neighbour round the corner. Put the exact address into the Environment Agency's long-term flood risk service, surface water included, and get an indicative quote before you get far into the purchase.
The postcode ratings combine several measures, surface water among them, and a postcode counts if any one of them puts it in a band. On that basis, about 10% of Ampthill's 209 postcodes are high on at least one measure, about 14% medium and about 42% low. Those are the shares to look at. The flood-zone figures above answer a narrower question.
The Environment Agency's rivers-and-sea property count lists only postcodes carrying some risk, and only one Ampthill postcode qualifies. It covers 19 properties. Four are at high risk and one at medium, and none of the high-risk properties are homes. If your house is not in that postcode, river flooding drops off the list of worries.
In the Environment Agency's modelled flood extents, 0% of postcodes are in the high-risk extent either with or without defences, and 0% in the low-risk undefended extent. The model includes no defences because it shows nothing for them to hold back. A buyer who hears the word "defended" about an Ampthill house has been told something that answers no question.
The nearest tide gauge is at Portsmouth, where the record from 1962 to 2023 shows the sea rising about 2 millimetres a year. That figure is a measured past rate at a port on the south coast. That Portsmouth is the closest gauge says most of what an Ampthill buyer needs to know about the sea.
Records show no historic flooding anywhere in the area. That counts for something, though it covers only what someone wrote down, and surface-water flooding often goes unrecorded unless it reaches a house.
On flooding, Ampthill is middling. The rivers and the sea are no concern, and the surface-water ratings on a tenth of postcodes keep it from being better than that.