Yes, and very little of it comes from a river. Hardly any of Cheam's postcodes are in the river flood zones. Nearly a fifth are rated high risk once every type of flooding is counted. The only river flood on record is more than fifty years old. In a suburb this far from the sea, the main risk is water that has nowhere to drain.
On the Environment Agency's river-and-sea mapping, about 2% of Cheam's postcodes are in flood zone 2 and fewer than 1% are in zone 3. The two zones don't overlap. Zone 3 is the highest-probability band, and zone 2 is the medium-probability fringe outside it, so a small zone 2 figure describes an extra strip of land and doesn't contain zone 3. The Environment Agency's record lists one recorded flood, in September 1968, when a main river spilled over a channel that had no raised defences.
Surface water is where Cheam's numbers change. The Environment Agency doesn't count surface water in its river-and-sea zones, but it does count in the postcode indicators set out below. The difference between the two is the flooding this suburb actually gets. Cheam has no river to blame for it.
Once climate change is allowed for, Cheam's share of postcodes in the river-and-sea flood zone stays at 0%. The rivers aren't the worry here, and that holds when the model looks ahead too.
Insurers price individual addresses, and surface water counts in their risk models even when the river flood map is clear. A house can be outside every river zone and still carry a surface water rating that pushes up the premium or the excess. Ask for a buildings insurance quote on the exact address while the survey is still being arranged. The quote shows how an insurer's model rates that house, which a postcode average can't.
When every measure is counted together, including surface water, about 18% of Cheam's postcodes are rated high risk on at least one of them, 22% medium and 41% low. These bands overlap with the zone figures above and use a wider measure, so the two sets shouldn't be added together or compared like for like. Nearly a fifth of postcodes rated high, against fewer than 1% in the top river zone, is the gap you most need to understand about Cheam.
Counting properties gives a sharper picture than counting postcodes. In the Environment Agency's assessment of risk from rivers and the sea, 17 of Cheam's postcodes carry some level of risk, covering 496 properties. Of those, 63 are rated high, 32 medium and 136 low, and 58 of the high-risk properties are homes. Postcodes with no river or sea risk at all aren't listed. If you're buying in one of those 17 postcodes, look the house up yourself.
Defences make little difference to the result. About half of one percent of Cheam's postcodes are inside the Environment Agency's high-probability flood extent with no defence in the model, and the same share again are inside it with a defence modelled. "Defended" means a wall or bank appears in the model. It doesn't mean the water stays out of the house.
The nearest tide gauge to Cheam is at Portsmouth, which measured sea level rising by about 2 millimetres a year between 1962 and 2023. The measure has to travel a long way to describe Cheam, and that distance is the reassurance. The sea is somebody else's problem here.
Cheam has a poor flood record for a place with so little river, almost all of it from surface water and the tight cluster of postcodes the Environment Agency lists. Most homes are fine. The ones that aren't need checking house by house, because a suburb-wide average won't tell you.