Eynsham has a low flood risk, which is unusual for a village that grew up beside a Thames ford. About one postcode in fifty is in the river's high-risk zone. A handful of properties are rated high risk, and only one of them is a home. Surface water adds more, though not much. The river runs past the village on the flood plain and, for the most part, leaves the houses alone.
The Environment Agency's river-and-sea flood zones put about 2% of Eynsham's postcodes in Zone 3, the high-probability band, and another 1% in Zone 2, the medium-probability fringe outside it. The Environment Agency has one recorded flood on file, in July 2007, when the main river overtopped a channel with no raised defences. Wharf Stream, the tributary where medieval Eynsham loaded its hay, malt and timber, still runs through the old trading end of the village. A river that has carried coal barges into Eynsham since the canal era has mostly kept to its own business since.
Surface water flooding works differently. It comes from rain landing on roads and gardens faster than drains can carry it away, and it does not respect the river zones. That is why the Environment Agency's postcode-level indicators, covered further down, flag more of Eynsham than the zone figures above.
The Environment Agency also maps how far the flood zones could reach once a climate allowance is added. On that measure, about 2% of postcodes fall inside. The edge of the risk barely moves with it, which is reassuring for anyone planning to stay a long time.
At the low end of the zones, cover should be straightforward to arrange, and insurers will price a postcode near the Thames on its own merits. The streets closest to Wharf Stream and the river need a closer look, and that is where an insurer's questions will start.
The Environment Agency's postcode indicators count a postcode if it rates on any one of several flood measures, surface water included. On that wider count, about 5% of Eynsham's postcodes rate high on at least one, 8% medium and 25% low. Because several measures go into it, this figure is broader than the river zones and covers different ground, so neither should be read as a correction of the other.
The Environment Agency's rivers-and-sea mapping counts properties as well as postcodes, and it lists only the eight postcodes in Eynsham that carry some risk. Among the 224 properties in those postcodes, 8 are rated high risk, 5 medium, 36 low and 6 very low. Only one of the eight high-risk properties is a home. A count that small means the real question for a buyer is whether the house being viewed is on that list. The Environment Agency's long-term flood risk service will answer that for any single address in a couple of minutes.
The modelled flood extents also show whether a defence stands in the water's way. About 2% of Eynsham's postcodes fall inside the high-risk extent where the model has no defence, and about 1% inside it where a defence is present. A defence in the model is a structure on a map. Whether it keeps any particular kitchen dry is a separate question that the model does not answer.
The nearest tide gauge is at Portsmouth, where sea level rose by about 2 millimetres a year between 1962 and 2023. That is a measured rate for the south coast and has no direct bearing on Eynsham. A village this far up the Thames has rainfall to think about, and the tide was never going to reach it.
Flood risk is one of Eynsham's real strengths. The risk that does exist is confined to a short, known list of properties, and the rest of the village sits clear of the river it was built beside.