Yes, more than most commuter towns, and most of the risk comes from water that never reaches a river. About one in eight postcodes sits in the river flood fringe. About one in five shows high risk on at least one measure once rain and runoff are counted. Several hundred properties are rated high risk. The Lea made Cheshunt's best scenery, and it also put the town on the flood maps.
On the Environment Agency's river-and-sea mapping, about 12% of Cheshunt's postcodes are in Flood Zone 2 and about 2% in Flood Zone 3. The two bands don't overlap. Zone 3 is the highest-probability ground next to the water, and Zone 2 is the medium-probability strip beyond it, so the outer band being the bigger one is normal. The River Lea, the Lee Navigation and the Small River Lea all run along the town's eastern side. The soils that made this valley good for market gardening are river deposits, and the river laid them down by doing exactly what the zones describe.
Surface water is the part those zones leave out. Rags Brook and Turnford Brook both run through Cheshunt Wash, a low-lying stretch on their way to the Lea, and heavy rain looks for the low ground whatever a river map says. The Environment Agency's records hold 73 flood events touching the area, covering about 8% of it. The most recent recorded event is from December 1947, when a main river overtopped a channel with no raised defences. Nobody alive in Cheshunt remembers that flood, which is why some buyers take the risk lightly.
The Environment Agency's climate-change allowance widens the picture. With it applied, about 18% of the area falls inside the flood zones, against the 14% of the two zones combined today. That is a modelled future flood outline, worked out by the Environment Agency.
For insurance, a home in the high-risk bands can expect closer questions from insurers, a higher premium or a larger excess. Older homes may be able to get cover through the government-backed reinsurance scheme, but homes built after 2009 are left out of it, which matters in a town that keeps building. Put the exact address into the Environment Agency's long-term flood risk service and get an insurance quote while the purchase is still at the offer stage.
Looking postcode by postcode, about 21% of Cheshunt's postcodes rate high on at least one of the flood measures, about 28% medium and about 55% low. Those measures include surface water alongside rivers and the sea, and a postcode only needs to trip one of them to count. So these shares come out larger than the river zones above, and they are a different measure, not a correction.
The Environment Agency lists 4,106 properties in the postcodes that carry any river-and-sea risk at all. Of those, 252 are rated high risk, including 214 homes, 178 medium, 1,255 low and 853 very low. Postcodes with no risk do not appear in the count. A few hundred homes on the high-risk list doesn't sound like many until one of them is the house you've just offered on.
Defences cover only part of the high-risk ground. About 2% of postcodes are in the high-risk river extent with no defence in the model, and about 1% are in it with a defence present. "Defended" means a defence is in the Environment Agency's model. It does not mean the defence keeps water out of a particular kitchen, and an agent who says "defended" is telling you a defence exists, not that the house will stay dry.
The nearest tide gauge to Cheshunt is at Portsmouth, where sea level rose by about 2 millimetres a year between 1962 and 2023. Cheshunt is a long way from the coast, so that rise matters far less here than the rain falling on the Lea Valley.
Flood risk is Cheshunt's weak point. It is concentrated in the low valley ground on the eastern side and around the brooks, and away from those spots most homes face little risk.