Coleford has a flood problem, and it comes mostly from rain. Rivers and the sea barely reach the town. Surface water is another matter, and about a fifth of postcodes rate high on at least one measure. No flooding is on record. The risk here runs downhill.
In the Environment Agency's river-and-sea flood zones, about 3% of Coleford's postcodes lie in zone 3, the highest-probability band, and about 1% in zone 2, the medium-probability fringe beyond it. The two bands don't overlap, so zone 2 is the extra strip around zone 3 and the smaller figure is no mistake. On that measure alone the town looks close to dry.
Surface water is where the picture changes. Coleford grew up around a ford in the valley of Thurstan's Brook, and a town built in a valley collects whatever falls on the slopes above it. Rainwater with nowhere to go takes the roads first and the low ground next, and none of that shows up in a flood zone drawn for rivers.
Under the Environment Agency's climate-change model, the share of postcodes in the flood zone grows to about 6%. That is the modelled zone expanding under a warmer climate, a forward look with no date attached to any of it.
For insurance, the gap between the two measures matters. A home outside the river zones can still carry a surface-water rating that an insurer's postcode check picks up, and a high rating on any measure can narrow the choice of policies and push the premium up.
Counting every measure together, rivers, sea and surface water included, about 21% of Coleford's postcodes rate high on at least one of them, about 14% medium and about 29% low. One postcode can be flagged by a single measure and still land in the high group, which is why these shares run so far above the zone figures.
The Environment Agency's rivers-and-sea mapping also counts properties. Across the 19 postcodes it lists as carrying some risk, 449 properties in all, 121 are at high risk, 22 medium and 43 low, and 85 of the high-risk ones are homes. Postcodes with no risk on that mapping aren't listed at all. A hundred and twenty-one properties is a small number until one of them is the house being viewed.
Defences make no visible difference here. About 2% of postcodes fall in the high-risk modelled extent without defences, and the same 2% fall in it with defences counted. A defence that appears in the model leaves the share exactly where it was, and in any case "defended" only ever meant something was drawn on a map.
Coleford is about six and a half kilometres from the coast at the median postcode, and the shoreline management plan covering that coast sets a policy of no active intervention for the next 20, 50 and 100 years. A policy is a stated intention that depends on money nobody has committed, and it says nothing about what defences stand there today. At this distance from the coast, it is background.
The nearest tide gauge with a long record is Liverpool's Georges and Princes Piers, which measured sea level rising by about 1.4 millimetres a year between 1858 and 1983. That is a past rate at a gauge a long way up the coast. Having to go to Liverpool for a reading shows how small a part the sea plays in Coleford's flood risk.
The Environment Agency records no historic flooding in the area. That is reassuring, though an empty record only means nothing was written down. The one check worth making is to put the exact address into the Environment Agency's long-term flood-risk service and read the surface-water result, since that is the measure carrying the risk in Coleford.
Coleford's flood risk is below average. Rivers and the sea hardly reach it, but enough of the town is exposed to surface water that a house sitting low in the valley deserves a closer look.