Putney carries more flood risk than its riverside setting would lead anyone to guess, and the Thames is responsible for very little of it. Hardly any of the area falls in the river's flood zones. About one postcode in six still gets a high flag on at least one flood measure. Rain that cannot drain away fast enough is part of that count. A buyer looking only at the river is watching the wrong water.
On the Environment Agency's river-and-sea mapping, about 1% of Putney's postcodes fall in Flood Zone 3, the highest-probability band, and about another 1% fall in Flood Zone 2, the medium-probability fringe beyond it. The two bands are separate, so a postcode counts in one or the other. The Thames gives Putney its embankment, its rowing clubs' frontage and its pier, and keeps almost all of its houses out of the river's own flood zones.
Surface water is where the numbers change. Rain that overwhelms drains and gutters is measured separately from the river, and it is folded into the wider postcode indicators described below. Those indicators flag far more of Putney than the river zones do, which means the risk on most affected streets comes from something other than the Thames rising.
The Environment Agency also maps how the zones could grow once a climate allowance is applied, and on that measure about 3% of Putney's postcodes fall inside. It is a modelled outlook for a warmer future, and it still leaves the river side of the picture small.
For insurance, a home in Putney with a surface-water flag is a different conversation from one with none, even if both are miles from any river zone. Put the exact postcode into the Environment Agency's long-term flood risk service and ask an insurer for a quote on that specific property while the purchase is still at the offer stage.
Counting every measure together, surface water included, about 17% of Putney's postcodes rate high on at least one flood indicator, about 19% rate medium on at least one, and about 39% rate low on at least one. The figures overlap, because a postcode can carry a low flag on one measure and a high flag on another. Neither the shares nor any single number from them says how an individual front door behaves in a heavy storm.
The Environment Agency's flood extents show no Putney postcodes in the high-probability extent at all, either where the model includes a flood defence or where it does not. About 2% of postcodes fall inside the low-probability extent with no defence present in the model. A defence in the model means a structure is there. It says nothing about how a given house fares if it is overtopped, and in Putney the question barely arises for the river because so few homes are in the line of it.
The nearest tide gauge in the national record is at Portsmouth, where the sea rose at about 2 millimetres a year across its measurements from 1962 to 2023. That is the rate the gauge recorded over those years, measured on the coast a long way from Putney.
No flooding is recorded across the area in the historic flood records. That is good news, and it is limited to events someone wrote down. Surface-water flooding on a single street is exactly the sort of thing that can go unrecorded and still leave a cellar wet.
Putney's flood risk is worse than its river suggests and needs checking address by address. One postcode in six with a high flag somewhere is enough to put it on the wrong side of comfortable.