Most of Freshwater is not at flood risk, and the part that is knows exactly who it is. A small share of postcodes sits inside the river-and-sea flood zones. About one in ten rates high on at least one flood measure. Nearly three in ten sit within five hundred metres of the coast. Small does not mean nowhere. Out here the whole question is which side of a line your address falls on, and the line is drawn tighter than the reputation of an island suggests.
Environment Agency mapping puts about 4% of the area's postcodes in flood zone 3, the highest-probability band for rivers and the sea, and about 1% in flood zone 2, which is the additional medium-probability fringe lying beyond zone 3 rather than wrapped around it. The geography behind those figures is not mysterious. Freshwater sits near the source of the Western Yar, whose estuary runs north to Yarmouth, with marshland along it, and water goes where water has always gone.
The zone maps cover rivers and the sea and nothing else. Surface water, the kind that comes off a chalk down, meets a drain built for a smaller century and takes the road instead, is not in them. What is on record here is eight recorded flood events, the most recent in June 1999, on a main river blocked at a bridge, with about 2% of postcodes falling inside a historic flood outline.
Apply the climate change allowance and the share of postcodes inside the modelled zones rises to about 8%. That is the forward-looking version of the same map, not a prediction of any particular winter.
For insurance, the practical effect is that a small number of addresses will be quoted very differently from their neighbours, and the difference will show up at quote stage rather than at viewing stage. Flood Re, the industry scheme that supports flood cover on household policies, does not cover homes built since 2009. Get an indicative quote for the exact address before instructing anyone, because a postcode-level answer is no use when the risk sits on one side of a lane.
Across the combined indicator, which folds surface water in alongside rivers and sea, about 11% of postcodes rate high on at least one measure, about 9% medium and about 14% low. Those bands overlap with the flood-zone shares above rather than adding to them, and a postcode can be flagged high on one indicator while sitting outside the river-and-sea zones entirely.
The count of homes is the more useful number. The Environment Agency's rivers-and-sea mapping lists 339 properties across the 25 postcodes that carry any risk at all, of which 125 are at high risk, 33 medium and 28 low. Ninety-one of the high-risk properties are residential. Every postcode with no risk is simply absent from that list, which is most of them.
About 4% of postcodes sit inside a high-risk extent with no defence present in the model, and about 4% inside a high-risk extent where a defence is present. Present in the model means a structure exists in the mapping. It does not mean the property behind it is safe, and it does not say anything about the condition of the thing or who is paying to keep it standing.
The sea is close. About 28% of postcodes sit within five hundred metres of the coastline, a threshold the mapping defines rather than a statement about any single house, with a median distance of roughly 760 metres and a closest measured distance of about four metres.
Every postcode here falls under a shoreline management plan, and the modal policy across the twenty, fifty and hundred-year horizons is no active intervention. That is a stated intention not to maintain defences on this stretch, which is a different thing from a defence existing today and a very different thing from a promise. At the nearest tide gauge, at Portsmouth, the measured rise across the record from 1962 to 2023 runs at about two millimetres a year. That is history rather than forecast, and it is the direction the shoreline policy has already been written around.
Average is the fair reading on flooding here. The risk is real, it is narrow, and it is mapped well enough that nobody buying a specific address needs to guess which category they are in.