Mostly no, with named exceptions. About one in thirteen postcodes sits in the highest river-and-sea flood-zone tier. About one in seven is inside the climate-adjusted version planners now use. The River Lavant runs through the city in culverts for a reason. Buy here with the surface-water map next to you, not after the offer is on the table.
The river-and-sea picture splits across two flood-zone tiers. About three per cent of postcodes fall inside the medium-risk zone, and roughly eight per cent inside the high-risk zone. The River Lavant, a winterbourne that surfaces unevenly through the year, runs through the city in underground culverts for part of its course. That is not a decorative choice. Anyone buying near the line of the old river bed should treat the address as a flood question first and a heritage question second.
The surface-water picture is the one buyers tend to underestimate. About seven per cent of postcodes carry a high surface-water flood risk, around twelve per cent a medium risk, and about a third some lower-tier risk that still matters when the rain arrives in the wrong sort of burst. Surface-water flooding is what happens when an inch of August storm hits a Roman street plan drained by Victorian pipework, and the pipework usually loses the argument. Most addresses are not in the high band, but most is doing a lot of work in that sentence.
The climate-adjusted flood zone, which factors sea-level rise and shifting rainfall into the long-range planning horizon, covers about one in seven postcodes. That is meaningfully larger than the current high-risk zone. The gap is the part of the city that is dry on paper today and unlikely to stay that way across the lifetime of a thirty-year mortgage. The Portsmouth tide gauge, the nearest long-record reference, has logged a sea-level trend of about two millimetres a year for more than six decades, which is the slow background to the faster-moving rainfall projections that drive the climate map. Buyers planning to stay should look at that map alongside the current one.
Insurance cover is generally available, but the price and the excess move sharply when the address falls inside any of the flood zones. Lenders increasingly ask for evidence of flood cover before completion, and properties inside the high-risk zone or with a recorded historic flood event often need a specialist insurer rather than a high-street name. About four per cent of postcodes here carry a recorded historic flood event on file. The 1993-94 West Sussex floods are within living memory for residents who lived through them, and they are the kind of event the climate map is built around.
So: average flood risk overall, with named exceptions that include the buried-river line, the lower-lying ground toward the harbour, and any postcode the climate map flags that the current map does not. Most of Chichester is fine. The fine line between most and not-most is where the surveyor earns the fee.