Anerley does have a flood risk, but it comes from heavy rain, and rivers and the sea barely come into it. Hardly any of the area is in a river or sea flood zone. More than a third of postcodes still rate high on at least one flood measure. That gap is surface water, rain that falls faster than the drains can take it. "No river nearby" is true here, and it is the wrong thing to be reassured by.
In the Environment Agency's river-and-sea flood zones, under 1% of Anerley's postcodes are in Flood Zone 3, the highest-probability band, and another fraction of 1% are in Flood Zone 2, the medium-probability fringe beyond it. The zones exclude each other, so those are separate slivers. Together they cover almost nowhere.
The real exposure is surface water. With the river and sea zones covering so little, nearly all of Anerley's flood rating comes from rainfall pooling on roads, gardens and low corners faster than the drains can clear it. Surface water flooding depends on dips in the ground, kerb lines and blocked gullies, and it can differ from one end of a street to the other.
The Environment Agency's climate-adjusted zone, which projects the river and sea zones forward, adds nothing here. It covers no part of the area. This forward look covers rivers and the sea only, so it leaves the rainfall risk exactly where it was.
For insurance, that means the address matters more than the area's overall figures. Insurers price surface water risk property by property, and a postcode flagged high can mean higher premiums, a larger excess, or questions about past claims, even for a house nowhere near a river. The Environment Agency's long-term flood risk service lets you search a single address and shows the surface water rating separately, and that is the one to look at for any house here.
At postcode level, about 37% of Anerley's postcodes rate high on at least one of several flood measures, 36% medium and 52% low. Each postcode is rated on its worst measure, with surface water counted alongside rivers and the sea, so the bands overlap and a single bad indicator is enough to put a postcode in a band.
The Environment Agency's rivers-and-sea mapping counts properties as well as postcodes. Of the 267 properties in the ten Anerley postcodes carrying any river or sea risk, one is rated high, 14 medium and 57 low, and none of the homes is in the high band. Postcodes with no river or sea risk do not appear in that count at all. On that measure, Anerley has one high-risk property, and it is not a home.
The modelled flood extents answer whether anything stands between the water and a house. About 0.4% of postcodes fall inside the high-risk extent without defences, and the same 0.4% fall inside it with defences included. Including defences in the model changes nothing here, which makes sense, because defences are built against rivers and the sea, and that is not where Anerley's water comes from. A defence appearing in the model never meant a house was safe anyway.
The nearest tide gauge is at Portsmouth, where sea level rose by about 2 millimetres a year between 1962 and 2023. That is a measured past rate at a gauge a long way from SE20, and coastal flooding is not part of Anerley's problem.
The Environment Agency's historic flood maps record no flooding in the area. That is reassuring as far as it goes, but those maps track rivers and the sea far better than water running off a road in a cloudburst, so a clean record says little about the risk that matters here.
Anerley's flood risk is poor overall. Rivers and the sea are no real threat, but surface water reaches a large share of its postcodes, and that rating, house by house, is the one to look up.