Houghton Regis has a real flood risk, and almost none of it comes from a river. The river-and-sea flood zones barely touch the town. Surface water is a different matter. More than a third of postcodes rate high on at least one flood measure. A buyer who only checks the river map has checked the wrong thing.
The Environment Agency's river-and-sea flood zones cover very little of the town. About 1% of postcodes fall in zone 3, the highest-probability band, and about 2% in zone 2, the medium-probability fringe that lies beyond zone 3 and is counted separately from it. On that measure alone, Houghton Regis is a dry town.
Surface water is where the risk lives. The town sits against the Chiltern Hills, and the post-war estates laid a lot of roof and tarmac over what used to be farmland, so heavy rain runs downhill across roads and gardens long before it finds a river. The river maps ignore all of that, which is why a home can be miles from any watercourse and still get wet.
With the Environment Agency's allowance for climate change added, about 4% of postcodes fall inside the river-and-sea flood zones. The planners' climate maps are already drawing the river's edge a little wider than today's.
For insurance, the address matters more than the town's reputation. Insurers price flood cover property by property, and a home in a surface-water hotspot can draw a higher premium or a bigger excess even though it is nowhere near a river. Get an indicative buildings quote on the specific house early, because it is the quickest way to learn how an insurer reads that street.
At postcode level, measured on any of several indicators including surface water as well as rivers and sea, about 37% of the town's postcodes rate high on at least one measure, about 26% medium and about 49% low. Because the indicators overlap, one postcode can count in more than one of those shares. That is the figure that turns a dry-looking town into one where flooding comes up in conversation.
Counting homes is more useful than counting postcodes. The Environment Agency's rivers-and-sea mapping lists 18 postcodes in the town that carry any risk at all, holding 623 properties. Of those, 31 properties are at high risk, 48 at medium and 124 at low. Every one of the 31 high-risk properties is residential. Postcodes with no river or sea risk do not appear in that list at all, so the count only covers the homes the Agency has flagged.
On defences, the Environment Agency's model puts about 1% of postcodes in the high-probability extent whether or not defences are counted. "Defended" there only means a defence appears in the model, and it makes no difference to the share here, so there is no wall or embankment changing the picture for these homes.
The nearest tide gauge on record is at Portsmouth, where sea level rose by about 2 millimetres a year between 1962 and 2023. That is the rate measured at a harbour on the south coast over those years, and it matters to Houghton Regis about as much as the price of deckchairs. The water this town worries about falls from the sky.
Flood risk is a genuine weakness here. The rivers mostly leave Houghton Regis alone, but the rain does not, and the share of postcodes on the wrong end of the surface-water measures is too high to wave away.