Yes, Thamesmead East is at serious risk of flooding, and almost all of it is in the highest-risk band. Nearly every postcode is in the top river-and-sea flood zone. Every postcode has a recorded flood. On the climate-adjusted maps the whole area is inside the zone. What stands between the river and the houses is a line of defences, and everything depends on that line holding.
On the Environment Agency's flood-zone mapping, about 99% of the area's postcodes are in flood zone 3. That's the highest-probability band for flooding from rivers and the sea. None are in zone 2, the medium-probability fringe that usually lies beyond zone 3. In Thamesmead East there is no fringe, because zone 3 runs to the edge of the area.
The Environment Agency's surface-water mapping, for rain that can't drain away, isn't published here as a separate figure. It is counted in the postcode-level indicators further down this page, together with the other measures.
The Environment Agency also maps how the flood zones are likely to look as the climate changes, and 100% of the area's postcodes are inside that climate-adjusted zone. That map shows how the modelled flood area could grow. It doesn't predict when any flood will happen.
For insurance, a home in flood zone 3 is usually one that insurers price individually and lenders ask about. The flood-zone label follows the house when it's sold. Expect cover to depend on the home's own history, its floor level and the insurer's view of the defences. Ask the conveyancer's environmental search which defence the house relies on and who is responsible for maintaining it. Insurers ask the same question, and it helps to know the answer first.
The site's postcode-level indicators count a postcode if it reaches a given risk level on any one of several measures, including surface water as well as rivers and the sea. No postcode in Thamesmead East reaches high on any of them. About 15% reach medium on at least one, and about 40% reach low on at least one. These indicators measure something different from the flood zones, which is why a high flood-zone share and no high-rated postcodes can both appear on this page.
The defences make the most difference here. In the Environment Agency's modelling with no defences, about 99% of postcodes are inside the high-probability flood extent. With the defences included, none are. The Agency's assessment of rivers and the sea, which counts individual properties, also puts no home at high or medium risk. In the model, a defence being present is a line on a map that has to be maintained, and it doesn't make a house safe. The area's most recent recorded flood came in February 1953, when the sea broke through a defence.
The nearest long-term tide gauge is at Dover. Between 1961 and 2010, sea level there rose at about 2 millimetres a year. That's the rate measured at Dover over those years. It isn't a projection for Thamesmead East, and it says nothing about how high the defences need to be in future.
On flooding, Thamesmead East is in a poor position. The land is as exposed as land gets, and the defences that keep it dry have failed here before.