Botley's flood risk comes from the sky, not the river. The formal river and sea flood zones cover none of the village, and there is no record of it having flooded in the past. What it carries instead is surface water risk, the kind that arrives when heavy rain has nowhere to drain and starts pooling where the ground and the drains give up. About a quarter of postcodes sit in the highest surface-water band. That is the fact that shapes the whole answer, and it is why the flood picture here needs a closer look than a village on the Hamble might first suggest.
Start with the water everyone worries about, and there is nothing to report. None of Botley falls into Environment Agency flood zone two, and none falls into flood zone three, the bands that mark land at risk from rivers and the sea. For a village that grew up around a river crossing and its mills, that is a genuinely clean result. The Hamble made the place and then, on the official maps at least, left it alone.
The surface water story is the one that matters. Around a quarter of postcodes sit in the high surface-water band, roughly another quarter in the medium band, and a bit under half carry at least some lower level of risk. This is rainfall flooding, driven by how the land slopes and how quickly the drains cope during a downpour, and it does not respect the tidy edges of a river zone. Two houses on the same street can sit on very different odds depending on which way the ground tips.
Look forward and the numbers nudge rather than lurch. Once climate change allowances are applied to the flood maps, about one postcode in twenty-five, roughly four in a hundred, edges into a flood zone that today reads clear. That is a small share, but the direction is the point: the exposure grows over the life of a mortgage rather than shrinking.
For insurance, this is a place to do the paperwork properly rather than assume. Surface-water risk shows up on a flood search even where the river zones are empty, and that is the kind of finding that can lift a premium or an excess on the affected homes. A buyer should order the flood report for the specific address, ask the seller whether the property has ever taken on water, and price any cover into the offer rather than after it.
Botley is below average on flooding, and the reason is worth stating plainly: the river and the sea pose no mapped threat, but surface water does, with about a quarter of postcodes in the worst band. Check the address, not the village.