Mostly no, though the River Mole has a record of its own. None of Hersham falls in the highest-risk river flood zone. A thin fringe is in the zone below it. The Mole has still come over its banks within recent memory. The Environment Agency rates the village low risk, and the river has ignored that rating before.
On the Environment Agency's river-and-sea flood maps, about 7% of Hersham's postcodes are in Flood Zone 2 and none are in Flood Zone 3. The two zones do not overlap. Zone 3 is the higher-probability land nearest the water, and Zone 2 is the band of medium probability beyond it. Hersham has the outer band and none of the inner one. Counted by property, the Environment Agency puts no homes in Hersham at high or medium risk from rivers and the sea. The low-risk homes are along the Mole side of the village, and the meadows by the river flood so that the houses do not.
Surface water is a separate problem, and the river maps do not show it. It happens when heavy rain cannot drain away fast enough, and it can affect a street nowhere near the Mole. The only surface-water evidence for Hersham comes from the postcode indicators further down, and those combine it with every other source.
The Environment Agency's climate allowance redraws the zones for heavier rain and higher river flows, and on that version about 19% of Hersham's postcodes would fall within them. That figure is a modelled view of a wetter future, with no date attached. It is the number to remember if you plan to stay for the long term.
For insurance, a home in Flood Zone 2 with no flood history should be routine to cover, though a postcode near the river can bring extra questions and a higher premium. Hersham's Environment Agency records list 40 recorded flood events, the most recent in January 2014, when the main river overflowed its channel at a stretch with no raised defences. About 13% of the area falls inside the historic flood outlines. Ask the seller directly whether the house flooded or made a claim that winter, because an insurer will ask you the same question. That answer is the most useful one you can get about any house on the Mole side.
Counting postcodes on at least one flood measure, surface water included, about 3% of Hersham's postcodes rate high, 12% medium and 48% low. These bands overlap with the river zones above, so the two sets of figures should never be added together. With no homes at high risk from the river, the postcodes flagged high are picking that up from another source, and surface water is the obvious candidate.
In the Environment Agency's modelled flood extents, none of Hersham's postcodes are in a high-risk area, defended or undefended. About 4% are in a low-risk extent with no defence in the model. A "defended" label would only mean a wall or embankment appears in the Environment Agency's model, so it would not settle anything anyway. Here the question hardly arises, because the river's high-risk ground has no houses on it.
The nearest tide gauge is at Portsmouth, where sea level rose by about 2 millimetres a year between 1962 and 2023. That is the rate the gauge measured on the coast, and Hersham is a long way inland. The sea plays no part in Hersham's flood risk.
Hersham's flood risk is middling. Most of the village is on dry ground, and the strip by the Mole has flooded before and still deserves a careful look.