Less than a town wrapped around a harbour has any right to expect. Most of the built-up area sits outside the river and sea flood zones entirely. No flooding is recorded in the area at all. The properties that do carry a real rating are counted in dozens, not thousands. The risk here is concentrated in a few waterside pockets rather than spread across the town, which makes the address matter far more than the postcode district.
On the Environment Agency's river-and-sea mapping, about 1% of the area's postcodes fall inside flood zone 3, the higher-probability band, and about 0.1% fall inside zone 2. Those two are separate bands rather than one inside the other: zone 2 is the additional medium-probability fringe sitting beyond zone 3, which is why it can legitimately be the smaller of the two here. Between them they describe a narrow strip, and the rest of the town is not in either.
Surface water is the risk that ignores the zone map, because it comes off roofs, roads and a steep hillside rather than out of a river. No standalone surface-water share is published for the area, so the honest position is that it is folded into the combined postcode indicator further down rather than measured on its own. On ground that pitches this sharply from the top of the town to the quays, it is the mechanism worth asking a surveyor about even where the zone map is clear.
Looking forward, the climate-adjusted extent covers about 7% of postcodes. That is the Environment Agency modelling what the flood zone looks like with future sea level and rainfall allowances applied, and it is a planning tool rather than a prediction of next winter. It is also several times the current zone 3 share, which tells you the direction the map is being drawn in.
For insurance, none of this is fatal, but it is not invisible either. Lenders and insurers price off the specific address, and a property inside the zone or carrying a high rating will attract questions, a higher excess for flood damage, or a request for a survey before cover is confirmed. Get an indicative quote for the exact address before you instruct a solicitor rather than after.
Taking every measure together, including surface water alongside rivers and sea, about 9% of the area's postcodes carry a high rating on at least one measure, about 11% medium and about 30% low. Those bands overlap with the flood-zone figures rather than adding to them, and a postcode can land in the high band on one indicator while sitting well clear of the river and sea zones.
Counted as homes rather than postcodes, the Environment Agency's rivers-and-sea mapping puts 70 properties at high risk, 34 at medium, 125 at low and 10 at very low, out of 871 properties across the 33 postcodes that carry any risk at all. Fifty-two of the high-risk properties are residential. Only postcodes with some risk appear in that count, so the rest of the town is absent because it has nothing to report.
On whether anything stands between the water and the house, the modelled extents split evenly: about 1% of postcodes sit in a high-probability extent with a defence present in the model, and about 1% in a high-probability extent with none. A defence being present in the model means a structure exists in the mapping, not that the property behind it is safe, and defences are specified to a standard they can be overtopped beyond.
The coast is close by design. About 55% of the area's postcodes sit within 500 metres of the shoreline, the nearest comes within 3 metres of it, and the median distance is around 418 metres. That 500-metre figure is a threshold the data uses, not a statement about any particular house.
The shoreline management policy for this stretch is hold the line, over the twenty, fifty and hundred-year horizons. That is a stated intention to maintain the defence position rather than retreat from it, which is the most favourable of the available policies, but it is an intention rather than a guarantee, and it does not by itself mean a defence already exists in front of a given property.
The nearest long tide gauge, at Devonport, recorded sea level rising by around 2.35 millimetres a year across its 1962 to 2015 record. That is a measured historic rate over half a century of readings, not a forecast of what happens next.
There is no recorded historic flooding in the area. That is genuinely reassuring rather than a technicality, though absence of a record is not the same as proof nothing has ever happened, and it says nothing about the climate-adjusted extents above.
Flood risk here sits somewhere in the middle: a quiet picture across most of the town, a short list of waterside addresses where it is a real and pricing-relevant issue, and a climate allowance that widens the map. Check the individual address on the Environment Agency's long-term flood risk tool before you get attached to the view.