Heston's flood risk falls from the sky. None of its postcodes is in a river or sea flood zone. About one in eleven still rates high on at least one flood measure, and a quarter rate medium. Nobody has recorded a flood here. Any risk Heston has comes from rain that has nowhere to go.
On the Environment Agency's river-and-sea mapping, 0% of Heston's postcodes are in flood zone 3, the higher-probability band, and 0% are in zone 2, the medium-probability fringe outside it. The River Crane is the nearest water of any size, and on those maps it stays in its own channel.
That leaves surface water, which is a different measure. When a storm drops more rain than the drains and gardens can take, water runs along roads and pools in the low spots. A suburb built over old farmland in the 1920s and 1930s has plenty of tarmac and roofs where fields used to soak the rain up. The Environment Agency's river mapping does not count any of this.
The Environment Agency's climate-adjusted zone, which shows how far river and sea flooding could spread with the extra rainfall and sea-level rise expected in future, takes in 0% of Heston's postcodes. On rivers and sea, even the version of the future the planners prepare for leaves Heston dry.
For insurance, that is mostly good news. A home outside the river-and-sea zones with no recorded flooding should get ordinary cover at ordinary premiums. The places where a quote might come back higher are the surface-water hotspots, so get a quote on the actual address early. If the house is one of the few that is flagged, a broker will want to know whether it has flooded and what the ground floor is like.
The postcode-level ratings show the surface-water side. Taking every measure the Environment Agency publishes, surface water included, about 9% of Heston's postcodes rate high on at least one, 25% rate medium and 50% rate low. These figures cover a different question from the flood zones and overlap with them, so the two should never be added together. The thing to check is the Environment Agency's long-term flood risk service for surface water at the exact postcode, since a high rating can apply to one road and miss the next.
Counted as homes and buildings, the river-and-sea risk is tiny. The Environment Agency's register lists one postcode in Heston with any river or sea risk, covering 58 properties. One of them is rated high and none medium or low, and that one property is not a home. The register only includes postcodes with some risk, so the other streets are left off because they have nothing to report.
On the defence question, 0% of postcodes are in the high-risk river flood extent with no defence in the model, and 0% are in it with a defence. Nothing in Heston relies on a flood wall, because the rivers don't reach the houses in the first place.
The nearest tide gauge is Portsmouth. It recorded sea level rising by about 2 millimetres a year between 1962 and 2023. That rate belongs to the south coast, and for a suburb this far inland it is the least relevant number on the page.
The records show no historic flooding anywhere in Heston. That is reassuring, but it only covers floods someone wrote down, and surface-water flooding on a back street often goes unrecorded. A seller who says the house has never flooded is telling the truth about rivers. On drains, it is worth asking the question directly.
Flood risk in Heston is middling. Rivers and the sea pose no threat at all, and the surface water that does pose one is patchy and concentrated on a minority of streets.