In places, and the places are exactly where you would guess. Most of the village sits high enough up the slope to watch the river do whatever it likes. A small number of homes at the bottom do not. Calstock grew around a working quay, which is a decision made about boats, not about insurance. This is a question about a specific address, not about the village.
On the Environment Agency's river and sea mapping, 3% of the area's postcodes fall inside flood zone 3, the highest-probability band, with a further 8% in zone 2, the medium-probability fringe that sits beyond zone 3 rather than wrapping around it. Those two bands are separate, not nested, which is why the outer one being the larger number is normal rather than a mistake.
Surface water is the risk the river mapping does not show. There is no separate surface-water share published for Calstock; it is folded into the combined postcode indicator further down. On a village built into a hillside, run-off down a lane in a heavy summer downpour is the mechanism that catches out people who checked the river and stopped there.
Looking forward, the same Environment Agency modelling puts 18% of postcodes inside a flood zone once the climate allowance is applied. That is a projection of where the zones move, not a forecast of a flood, and it more than doubles the footprint of the present-day mapping.
For insurance, this matters more than most buyers expect. A property inside a mapped zone can attract higher premiums, a larger excess on flood cover specifically, or questions from an insurer that arrive after the offer has been accepted. The village-level picture is irrelevant to that conversation. Get an indicative quote on the actual address before instructing a solicitor.
Taking every measure together, including surface water, 10% of postcodes here rate high on at least one flood indicator, 13% medium and 30% low. Those bands overlap with the river and sea zones above rather than adding to them, so they describe the same water counted a different way.
The count of homes is the more useful number. Only nine postcodes in Calstock carry any mapped risk at all, and within those, the Environment Agency's rivers and sea mapping identifies 162 properties. Of those, 31 sit at high risk, 3 at medium and 24 at low. Sixteen of the high-risk properties are residential. That is a small, specific set of houses rather than a village-wide problem, and if you are buying one of them you would very much like to know before rather than after.
On whether anything stands between the water and the buildings, the modelled extents split evenly: 3% of postcodes sit inside a high-probability extent where a defence is present in the model, and 3% inside one where no defence is present. Defended in this context means a structure exists in the modelling, not that a house behind it is safe. Defences are designed to a standard, and water occasionally exceeds it.
Every postcode in Calstock sits within 500 metres of the water as the mapping measures it, which is what happens when a village is built on a tidal river. The closest is 6 metres from it. The median is 114 metres.
The shoreline management policy covering this stretch is no active intervention, and that is the stated position across the 20, 50 and 100 year horizons. It means there is no intention to build or maintain defences here over the next century. A policy is an intention rather than a guarantee, but in this case the intention is unusually easy to summarise.
The nearest tide gauge, at Devonport, recorded sea level rising by about 2.35 millimetres a year across its record from 1962 to 2015. That is a measured historic rate over that period, not a projection.
One genuinely encouraging fact: no historic flooding is recorded in the area. That is not proof nothing has ever happened here, since records only capture what was reported and mapped, but a clean history is better than the alternative and worth weighing.
Flood risk in Calstock lands in the middle. It is not a village with a flooding reputation, and the overwhelming majority of homes are nowhere near the water. It is also a village where a small number of properties carry real, mapped, high-level risk, and no amount of averaging across the other postcodes helps the buyer who ends up in one of them.