Yes, Esher has a real flood risk, though it's patchy rather than everywhere. A fifth of postcodes are in the river flood fringe. Almost none are in the highest-risk zone. About a third have flooded at some point on record. The water doesn't reach every street, but the streets it does reach are well mapped.
In the Environment Agency's river-and-sea flood zones, about 21% of Esher's postcodes are in Zone 2 and under 1% are in Zone 3. The two zones don't overlap. Zone 3 is the highest-probability land, and Zone 2 is the medium-probability band beyond it. Here that outer fringe is much bigger than the core. The River Mole runs to the west of the town. It usually stays in its banks, and much of Esher's flood risk is about how often it doesn't.
Rain and small streams are the other side of it. The Environment Agency holds 105 recorded flood events for the area, and historic flood outlines touch about 31% of Esher's postcodes. The most recent recorded event was in 1968, when an ordinary watercourse overflowed because its channel couldn't carry the water. Ditches and brooks were the cause that time rather than the river, and they don't usually come up in a description of a nice detached house.
With the Environment Agency's allowance for climate change, about 6% of Esher's postcodes are in the climate-adjusted flood zone. That's a modelled look ahead and a planning tool, and it only tells you which edges of the map are expected to move.
Insurance follows the same maps. A home in or near a mapped zone, or one with a flood claim in its past, can be harder to insure and cost more, and the excess is often where the cost shows. Ask the seller directly whether the house has ever flooded or had a flood claim, and get the answer in writing through your conveyancer. People forget things more easily in conversation than they do on a signed form.
Count every type of flooding together and the picture widens. About 7% of Esher's postcodes are high risk on at least one flood measure, including surface water, 11% are medium and 43% are low. Those bands overlap with the river-and-sea zones above, so they measure something different and can't be added to them. A low-risk score on at least one measure is common across the town.
Counting properties is more useful than counting postcodes. The Environment Agency's rivers-and-sea mapping lists 2,186 properties in Esher postcodes that carry some risk: 1 at high risk, 80 at medium risk, 1,438 at low risk and 28 at very low risk. The single high-risk property is residential. Postcodes with no risk at all don't appear in that count. Most of the exposure is at the low end, but the medium band is still 80 homes.
The Environment Agency also models whether defences affect the picture. About 25% of Esher's postcodes are inside the high-risk flood extent without defences, and the share is the same about 25% with them. In this model, then, defences don't change the high-risk footprint. "Defended" in that model only means a defence is shown on the map, and in Esher the map is the same either way. A seller who uses the word to calm a buyer down is relying on a technicality.
Sea level matters less here than inland flooding. The nearest tide gauge is at Portsmouth, where the recorded rise was about 2 millimetres a year over its record from 1962 to 2023. That gauge measures the coast, and Esher's flood risk comes down from the Mole and the local brooks.
Flood risk is Esher's weakest point. For many streets it's minor, but in the low-lying parts it's serious enough that a buyer should check the specific house before making an offer.