On the official maps, Kennington is about as exposed to flooding as a district can be. Nearly all of it is in the Environment Agency's highest river-and-sea flood zone. Under the climate-change allowance, almost every postcode is inside a flood zone. About a third of postcodes fall in the high-probability flood extent with no defence in the model. The Thames defences are what separate that map from the day-to-day reality of living here.
About 95% of Kennington's postcodes are in Flood Zone 3, the Environment Agency's highest-probability band for flooding from rivers and the sea. Another 3% are in Flood Zone 2, the medium-probability band just outside it. The two zones don't overlap, which is why the medium band is the smaller figure here. Zone 3 has taken in almost everything, and Zone 2 is the thin strip left at the edge.
Those zones cover rivers and the sea only. Rain that falls faster than the drains can take it is measured separately, and it shows up only in the postcode-level figures further down, combined with other sources. The River Effra once divided Kennington from Vauxhall, and the River Neckinger ran roughly along Brook Drive. Both have since been diverted into underground culverts.
Under the Environment Agency's climate-change allowance, about 100% of the district's postcodes fall in a flood zone. That is the agency's modelled view of a wetter future. With only a handful of postcodes left outside the zones today, there was very little room for the allowance to add more.
For insurance, the zone map is a starting point that insurers check against the exact address. The Environment Agency's separate assessment of risk from rivers and the sea counts properties and allows for the defences. It rates about 8,800 Kennington properties at very low risk and none at high, medium or low. Premiums usually follow that address-level rating, not the zone shading. A buyer can ask for an indicative quote on the specific flat early, while there is still time to walk away. That quote is the clearest sign of how an insurer actually sees the address.
A wider postcode measure, which counts a postcode if it flags on any one of several flood measures including surface water, puts about 6% of Kennington's postcodes at high risk on at least one of them, about 10% at medium and about 35% at low. That 6% is the figure to look at for rain-driven flooding. It is small, and it is the part of the risk the Thames wall does nothing about.
In the Environment Agency's modelled flood extents, about 32% of Kennington's postcodes fall in the high-probability extent with no defence present in the model, and none in a high-probability extent where a defence is modelled. About 68% fall in the low-probability extent, also undefended. In this model, "defended" only means a structure is present, and here the model doesn't show one. The agency's records list 116 flood events in the area. The most recent was in 1928, from a main river, and the cause recorded was overtopping of defences. The last time the water came into Kennington, it came over the wall.
The nearest tide gauge in the record is at Portsmouth. It measured sea level rising by about 2 millimetres a year between 1962 and 2023. That is the rate it recorded over those years, and it is the closest long tide record available for a district well up the Thames from the sea.
Flood risk is one of Kennington's poor points. The district is almost entirely inside the flood zones, and the defences that keep it dry in practice don't change how the maps classify it.