Highworth has no river flood risk to speak of, though surface water is another matter. No postcode sits in a river or sea flood zone. The town stands on a hill above the Thames valley. A minority of postcodes still flag high on at least one flood measure. Any risk here comes from rainfall on the streets, not from the river.
On the Environment Agency's river-and-sea mapping, 0% of the area's postcodes fall in flood zone 3, the highest-probability band, and 0% fall in flood zone 2, the medium-probability fringe beyond it. Those are separate bands, and here both are empty. Being the highest town in Wiltshire settles the river question more convincingly than any flood defence could. Any surface-water figure elsewhere on this site uses a different measure and shouldn't be read against these zones.
Surface water is where the remaining risk sits. It comes from heavy rain that can't drain away fast enough, and it doesn't care how far the nearest river is. On a hilltop the water runs off quickly, and that can mean trouble for whichever street sits at the bottom of the run. The river-and-sea zones don't capture any of this, which is why a clean zone check is only half the answer.
Looking forward, the Environment Agency's climate-adjusted zones also put 0% of postcodes inside the flood area. On that projection, higher future flows still don't reach a town sitting this far above them.
For insurance, a river-zone check this clean usually helps with cover and pricing. It doesn't cover every address, though, because insurers increasingly look at surface water too. A property on one of the flagged postcodes may get asked questions that the rest of town doesn't. Get an indicative quote on the exact address before the solicitor is instructed, not after exchange.
At postcode level, and folding surface water in alongside rivers and sea, about 7% of postcodes rate high on at least one flood measure, about 8% rate medium, and about 26% rate low. These bands overlap with the zone figures above and can't be added to them. They measure something broader. In practice, most of Highworth doesn't register at all, and a small share does, almost certainly because of surface water, given that the river zones are empty.
The question of whether any defence stands between a house and the water doesn't arise here. The modelled flood extents put 0% of postcodes in a high-risk area with no defence, and 0% in a high-risk area with one. On the Environment Agency's model, there's no river water heading for Highworth that would need defending against.
The nearest tide gauge is at Portsmouth, where the recorded rise between 1962 and 2023 averaged about 2 millimetres a year. That is a measured historic rate at a coastal gauge a long way from Highworth, not a forecast for it. For a hilltop town this far inland, it's background reading rather than a buying factor.
The records show no historic flooding across the area, with 0% of postcodes inside a recorded flood outline. That's reassuring. It is not proof that no garden, cellar or road has ever taken water, only that no event was big enough to be mapped.
Flood risk in Highworth is middling. That's not because of any river, which the hill has dealt with, but because of the minority of postcodes where surface water shows up. Check the exact address, and on most of the town's streets the answer should come back clean.