Parts of it are, and the River Mole decides which parts. Only a sliver of postcodes fall in the river flood zones. About a fifth rate high on at least one flood measure. The Mole has overflowed within the last few years. The risk covers a small part of Cobham, it is real, and it is usually sold to you as a river view.
The Environment Agency's river-and-sea flood zones cover very little of Cobham. About 2% of its postcodes are in flood zone 3, the highest-probability band, and about another 2% are in zone 2, the medium-probability fringe beyond it. The two bands don't overlap, which is why the outer zone can be the smaller number. The Mole flows past the High Street on the low eastern bank, and the higher sandy ground of the heaths on the outskirts mostly stays out of it.
Rivers are only part of the picture. The Environment Agency has 49 recorded flood events in its outlines for Cobham, the most recent in January 2014, when a main river overflowed a channel with no raised defences, and about 9% of postcodes fall inside areas that have flooded before. Rainwater that can't drain away can reach streets nowhere near the river. In 1986 the Thames Water Authority rebuilt the weirs by the mill and shored up its foundations as part of its flood-control spending, after decades of the river slowly eating the mill island. The mill was the first building here to find out where the water wants to go.
The Environment Agency's climate-adjusted mapping, which models future rainfall and river flows, puts about 4% of Cobham's postcodes in the flood zones. That is a modelled scenario for a wetter future, and it does not tell you when.
Insurers price by the individual property, not the village average. A house in the river zone or inside a recorded flood outline can expect more questions, a higher premium or a larger excess. A house up on the heath will mostly not notice. Get an indicative buildings-insurance quote for the exact address while the survey is still being arranged, since that quote is the number that will follow the house around.
The postcode-level picture is broader because it combines every indicator, surface water included, and counts a postcode if it rates on at least one measure. On that basis about 22% of Cobham's postcodes rate high on at least one measure, 21% medium and 46% low. These bands overlap with the flood-zone shares above and measure something different, so they can't be added together.
Counting homes makes it more concrete. Only 31 postcodes carry any river-or-sea risk at all, and they contain 628 properties. The Environment Agency's rivers-and-sea mapping puts 173 of them at high risk, 128 of those residential, plus 51 at medium risk, 47 at low risk and 9 at very low risk. Every other property in Cobham is outside that river-and-sea count, though not necessarily outside the surface-water picture.
Defences make no difference in the model. About 2% of postcodes are in the high-risk extent with defences included, and the same 2% without them. "Defended" only ever means that a defence appears in the Environment Agency's model, and here it changes nothing. A seller describing the riverside as protected is describing something the mapping can't find.
Sea level matters little this far inland. The nearest tide gauge, at Portsmouth, recorded a rise of about 2 millimetres a year between 1962 and 2023. That is the coast's problem, measured on the coast.
Flood risk is one of Cobham's weaker points. Most homes will never notice it, but for the few hundred that the Environment Agency's maps pick out, the river is the first thing the insurer will ask about.