Bethnal Green is out of reach of rivers and the sea, but it can still flood from rain. None of the area lies in the official river or sea flood zones. Raising the zones for climate change still leaves it out. More than one postcode in ten still carries a high flood rating on at least one measure. The problem here is rainwater the drains can't clear.
On the Environment Agency's river-and-sea flood map, 0% of the area's postcodes fall in Flood Zone 3, the highest-probability band, and 0% in Flood Zone 2, the medium-probability fringe just beyond it. In other words, no postcode here shows up on either band.
The risk that remains comes from surface water: heavy rain on streets, roofs and yards that the drainage can't take quickly enough. Surface water doesn't follow a riverbank, so it can turn up in the middle of a neighbourhood that has no river at all.
The Environment Agency's climate-adjusted version of the flood zones, which widens them for a wetter future, still puts 0% of postcodes in them. On the river-and-sea measure, both the present and the modelled future come out clean.
For insurance, an area outside the river-and-sea zones is usually the easier case. A postcode with a high surface-water rating can still come up in an insurer's own model, though, and insurers price the individual property. Put the exact address into the Environment Agency's long-term flood risk service and look at the surface-water result, because the area-wide clean zone map says nothing about that.
Look across every measure, surface water included, and the picture changes. About 13% of the area's postcodes rate high on at least one of the Environment Agency's flood indicators, about 17% rate medium on at least one, and about 35% low on at least one. These shares count a postcode once it trips any one of several measures, which is why they can sit next to a zone map showing none. The difference between a blank zone map and one postcode in eight rated high is the whole point of this answer.
On the question of defences, the Environment Agency's modelled flood extents put 0% of postcodes in a high-risk river or sea extent, with defences or without. Bethnal Green has nothing to defend against on that measure, so it has no defence to depend on either. A surface-water flood is a matter for the drains, and the drains aren't counted as defences.
The nearest tide gauge in the record is at Portsmouth, where the sea rose by about 2 millimetres a year between 1962 and 2023. That is a rate measured on the south coast over six decades, and it has little bearing on streets this far from open water.
The Environment Agency's records show no historic flooding in the area. That is a good sign, though a record shows only what someone mapped, and surface-water flooding on a single street is the kind least likely to be mapped.
Flood risk in Bethnal Green is middling. Rivers and the sea leave it alone, and the danger is rain with nowhere to drain, on a minority of streets. Check whether yours is one of them.