Not from rivers or the sea. Illogan sits inland and uphill, and the mapped flood zones miss it completely. What water it does get arrives off roads and fields during heavy rain. Around one postcode in seven still carries a high rating on at least one flood measure. The question here is not whether a river bursts. It is where the rain goes once it lands.
On the Environment Agency's river-and-sea flood zones, none of Illogan's postcodes fall inside flood zone 3, and none fall inside flood zone 2 either. The two zones are separate bands rather than one inside the other, with zone 2 marking the additional medium-probability fringe lying beyond zone 3, so a village can sit outside both and this one does. That is the single most useful fact on this page for anyone worried about a watercourse.
What remains is surface water, and in a village built on a slope above the coast that is the realistic mechanism. Rain moving downhill across roads, yards and hard standing does not need a river to put water through a door. The Environment Agency's postcode indicators cover 119 of Illogan's postcodes, and surface water is what drives most of what they flag.
The forward look does not change the answer. Under the climate-adjusted flood zone, which adds an allowance for future sea level and river flows, the share of Illogan postcodes affected remains zero. Whatever else warming does to Cornwall, it does not put a river through this village.
For insurance, that combination is about as good as a Cornish postcode gets. Sitting outside the river-and-sea zones is what insurers price off first, so most buyers here should find cover quoted at ordinary rates rather than loaded. Surface-water history at a specific address is the thing that can still complicate a quote, so it is worth getting an indicative quote before instructing a solicitor rather than after exchange.
Taking all the indicators together, including surface water alongside rivers and sea, about 15% of Illogan's postcodes carry a high rating on at least one measure, about 18% a medium rating and about 44% a low one. These bands overlap the zone figures rather than adding to them, and a postcode counts here if any single indicator flags it. This is the number that makes the flood picture look worse than the flood zones suggest, and it is doing so honestly: the water is real, it just is not a river.
Counted as homes rather than postcodes, the Environment Agency's rivers-and-sea mapping lists only 3 Illogan postcodes carrying any risk at all, covering 45 properties. Of those, 7 sit at high risk, with 6 of the 7 residential, none at medium and 3 at low. Postcodes with no risk do not appear in that mapping at all, which is why the total is so small.
On defences, the modelled flood extents put zero percent of the area inside a high-risk extent whether defended or undefended. There is nothing standing between the water and the houses because the mapping does not place the water there in the first place.
The coast is covered by a shoreline management plan across every postcode, with the nearest sea about 1.5 kilometres away and a typical postcode around 2.7 kilometres from it. The stated policy is to hold the line over the next twenty years, moving to hold the line or managed realignment over the fifty and hundred year horizons. A policy is an intention to maintain defences, not a guarantee that funding arrives, and not a defence that already exists.
At the nearest tide gauge, at Devonport, sea level rose at about 2.35 millimetres a year across the 1962 to 2015 record. That is a measured historic rate over that period rather than a projection.
No historic flooding is recorded for the area. That is genuinely reassuring, though an absent record is not the same as proof nothing has ever happened, particularly for surface water, which tends to be reported to insurers rather than to national datasets.
Flooding is the weaker side of Illogan's environmental ledger, and the reason is the rain rather than the sea. The village earns a clean record on rivers and coast, then gives some of it back on surface water, which means the risk is address-specific and worth checking street by street rather than village-wide.