Welling has very little river or sea flood risk, but it does have a real surface-water problem, which is why its flood picture is worse than the map suggests. Rivers and the sea barely touch it. The rain is the problem. About one postcode in five rates high on at least one flood measure, and most of that is water running off roads and gardens with nowhere to go.
On the Environment Agency's river-and-sea flood zones, about 1% of Welling's postcodes are in Zone 3, the highest-probability band, and none are in Zone 2, the medium-probability fringe beyond it. A town with no river through the middle and the coast a long way off was never going to show much here.
Surface water is a different story. The Environment Agency maps surface-water flooding separately, and it is the reason the combined postcode measure further down is much higher than the zone figures. The water comes from heavy rain on tarmac and roofs, not from overflowing rivers, and it gathers in whichever dips the roads happen to have.
The climate-adjusted version of the flood zones, which shows how the river-and-sea picture shifts once a changing climate is allowed for, puts none of Welling's postcodes inside it. As far as rivers and sea go, the future looks much like the present.
For insurance, the numbers split cleanly. A home outside every zone with a clean surface-water record should be easy to insure. A home on a high-rated postcode may get a higher premium or awkward questions, and the rating of the street matters more than the town's. Get a quote on the exact address early, and read the flood section of your conveyancer's environmental search alongside it.
Across all of the Environment Agency's measures together, rivers, sea and surface water, about 22% of Welling's postcodes rate high on at least one, 27% medium and 49% low. A postcode counts if any one of several measures flags it, so this share is bound to be larger than any single flood zone figure and should not be read as the same thing.
The rivers-and-sea mapping also counts individual properties. Only postcodes with some risk appear on it, and in Welling that is just eight postcodes holding 233 properties. Of those, 68 are rated high risk, 67 of them homes, along with 18 medium and 22 low. For a town this size that is a small and specific list, and the useful question is whether the house you are looking at is on it.
On whether anything holds the water back, about 1% of Welling's postcodes are inside the Environment Agency's high-risk extent with no defence in the model, and about 2% are inside it with a defence modelled. A defence in the model means a wall or embankment exists on the Environment Agency's map. It says nothing about whether it would hold in a storm or whether it protects any particular house.
The nearest tide gauge with a long record is at Dover, where sea level rose by about 2 millimetres a year between 1961 and 2010. That rate was measured over those years only. Dover being the nearest gauge shows how far Welling really is from the sea.
There is no recorded flooding anywhere in Welling. That is reassuring, but a record only holds what someone reported, and surface water that fills a road for an afternoon rarely makes it into one.
Flood risk is one of Welling's weaker points: below average overall, driven almost entirely by surface water on a minority of streets, and it pays to check which side of that line a house is on.