Parts of Littlehampton flood. Most of it does not. About 8% of postcodes sit in the highest river-and-sea flood zone, another 3% in the medium zone. Around one in eight postcodes carries some high-tier surface-water exposure. Which puts the town in the category of coastal places where the map matters more than the average, and the specific address matters more than the map.
On the river-and-sea side, the Environment Agency's flood zones cover about 8% of the area in zone 3, the highest-probability tier, and about 3% in zone 2, the medium tier. That is what you would expect for a town built at the mouth of the River Arun, with the English Channel on one side and the tidal river on the other. The zone 3 land includes stretches close to the river, the harbour, and the seafront. Buying in there is buying into a known category rather than a surprise, and the flood report on the specific title deed will tell you which side of the boundary the front door actually sits on.
Surface-water flooding is a separate risk with its own map. Around one in eight postcodes here shows some high-tier surface-water indicator, another one in six shows medium, and roughly one in three shows some low-tier signal. Surface water is what happens when heavy rain lands faster than the drainage takes it away, and it does not respect the river-and-sea flood zones. A postcode outside the tidal zones can still take water in the wrong storm, and low-lying streets several roads back from the river are as much in play as the seafront ones.
Under the climate-adjusted flood allowance that plans for a wetter and rougher future, nearly one in five postcodes falls inside the projected flood footprint. That is more than double the current zone 3 share. Which is the honest forward look: today's map understates what the next generation of buyers, insurers, and lenders will be assessing when the maps are redrawn to reflect the sea-level trend the Portsmouth tide gauge has already been recording.
On insurance, the split matters. Property in the higher flood zones typically attracts higher premiums and, at the edges of those zones, cover that is harder to find on standard building policies. Cover does exist for most properties in flood-affected postcodes, and the government-backed reinsurance scheme Flood Re helps keep policies available and affordable for many older homes, though it does not cover properties built since 2009. The proper move before offering on any property here is to pull the flood report on the specific address, ask the seller for a claims history, and check what the insurance renewal actually costs, rather than trusting the postcode-level average to speak for the doorstep.
Littlehampton's flood risk is not the exceptional part of the town, and not the part you can safely ignore either. A town at the mouth of a river on the English Channel has some serious pockets and some quiet ones, and which side of that split you land on is decided by the specific address and its distance from the water.