Yes. Rainham has a serious flood risk, and the defences along the Thames are what hold most of it back. About a quarter of postcodes are in the highest-risk river-and-sea zone. Take the defences away and nearly a fifth would be at high risk, while with them in place hardly any are. The sea has got past those defences before.
On the Environment Agency's river-and-sea flood maps, about 25% of Rainham's postcodes fall in flood zone 3, the highest-probability zone. Another 8% are in zone 2, the medium-probability band just outside it. The two zones don't overlap, so zone 2 being smaller simply means the land climbs steeply away from the riverside. The marshes along the Thames are barely above sea level, and the tidal Ingrebourne runs down the western edge. The village grew up on the gravel further north, which is higher.
There is no separate published surface-water figure for Rainham. Heavy rain is counted inside the combined postcode measure further down, together with rivers and the sea, so surface water can't be pulled out and given its own number here.
When the Environment Agency redraws its zones with an allowance for climate change, about 55% of postcodes fall inside them. That's a planning scenario for the decades a mortgage runs, and it puts more than half of Rainham inside the line.
Insurance follows the map. A home in zone 3, or on the edge of the marsh, can find cover harder to get and more expensive. A house up on the gravel can be a much easier conversation with an insurer. Get an indicative buildings-insurance quote for the exact address early on, because the premium may decide whether the house is affordable at all.
Postcode by postcode, about 7% are rated high risk on at least one of several measures, a count that includes surface water as well as rivers and the sea. Another 19% are rated medium and 48% low. It counts a postcode once if any of those measures flags it, so a street with one bad drain appears alongside one with the river at the end of the garden.
The Environment Agency's mapping of risk from rivers and the sea counts properties, and it only lists postcodes that carry some risk: 224 of them, holding 6,238 properties. Of those, 17 are at high risk, 41 at medium, 1,414 at low and 3,267 at very low. None of the 17 high-risk properties is a home. That count looks far calmer than the flood zones because it allows for the defences, and the zone maps don't.
The defences explain the gap. Without them, about 18% of Rainham's postcodes would be inside the high-risk flood extent. With the defences in the model, the share drops below 1%. That means a defence appears in the Environment Agency's model, and it says nothing about whether the defence will hold. The agency has 194 recorded flood events in the area. The most recent, in January 2003, came from the sea after a defence failed, and that history is behind every "defended" label on the map.
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 is the rate measured at Dover over those years, and the gauge isn't in Rainham.
Rainham's flood risk is worse than average. A buyer is depending on defences that have failed here before, so this is a below-average result that only looks fine because the walls are in place.