Not from rivers, which is the risk most buyers ask about and the wrong one to worry about here. Nothing in the village sits in the river-and-sea flood zones. Nothing has flooded on the recorded history. Yet roughly one postcode in seven still rates high on at least one flood measure. Whatever water threatens Alderholt is falling out of the sky rather than arriving down a channel.
Start with the Environment Agency's flood zones, which cover flooding from rivers and the sea. Zone 3, the high-probability band, covers none of Alderholt's postcodes. Zone 2, the medium-probability fringe that sits outside zone 3 rather than including it, also covers none of them. Both at zero is unusual enough to be worth saying twice. For a village in a county threaded with chalk streams, the parish has ended up on ground the rivers do not reach.
Which leaves surface water, and that is where the risk in Alderholt actually lives. The postcode-level flood indicators fold surface water and groundwater in alongside rivers and sea, and since the river-and-sea component here is zero, anything showing up in those ratings is water that cannot drain away fast enough after heavy rain. That is a different problem with different consequences. It arrives quickly, it does not respect the contour lines a river obeys, and it is far less visible when you view a house on a dry Saturday in June.
The forward look does not change the picture. The Environment Agency's climate-adjusted zone, which models what the river-and-sea extent looks like with future sea level and rainfall allowances built in, also covers none of the area. Alderholt is not one of those places where the risk map today is comfortable and the risk map for 2070 quietly is not.
For insurance, that combination usually reads well. Underwriters price hardest on river and coastal exposure, and a property with no zone designation and no recorded flood history is a straightforward proposition. Surface-water risk is priced too, and more finely than it used to be, so an individual address with a high indicator rating can still attract questions or an excess that a neighbour two hundred metres uphill never sees. This is an address-level question, not a village-level one, and the village-level answer will not save a specific house.
At postcode level, the numbers are these: around 14 percent of Alderholt's postcodes rate high on at least one flood measure, around 18 percent rate medium, and around 35 percent rate low. Those bands overlap with the zone figures above rather than adding to them, because they are counting a broader set of indicators. The honest reading is that most of the village carries little or nothing, and a minority of postcodes carry something worth checking before an offer.
On defences, the modelling gives a clean answer: none of Alderholt's postcodes sit inside a modelled high-risk extent at all, defended or undefended. That matters because "defended" in this modelling only means a defence is present in the model. It is a statement about infrastructure existing, not about a house being safe, and plenty of flooded properties have sat behind something an engineer signed off. Alderholt does not need to have that argument, because it is not inside the extent in the first place.
Sea level is background rather than foreground. The nearest tide gauge with a long record is at Portsmouth, where the measured rise across the 1962 to 2023 record runs to about 2 millimetres a year. That is a historic rate over six decades of readings rather than a forecast, and for an inland Dorset village it sets regional context rather than a direct threat.
There is no recorded historic flooding anywhere in the area. That is genuinely reassuring, and it is worth being precise about what it means: no recorded event is not the same as no event ever, because records are patchy and rural surface-water flooding has a long tradition of never making it into a database. It is evidence of a good history, not proof of an unbroken one.
Flood risk in Alderholt is middling, which is a better result than it sounds. The rivers are a non-issue and the climate projections leave that unchanged, but a minority of postcodes carry a high surface-water rating, so put the exact address into the Environment Agency's long-term flood risk tool before you get attached to the kitchen.