Yarnton's flood risk is moderate, and it comes from rain more than rivers. None of the village is in a river or sea flood zone. A small slice is flagged once climate change is factored in. Roughly one postcode in seven still carries a high rating on at least one flood measure. A clean river map covers part of the question, and a buyer here needs the rest of it.
On the Environment Agency's river-and-sea flood zones, none of Yarnton's postcodes fall in zone 3, the highest-probability band, and none fall in zone 2, the medium-probability fringe beyond it. On that measure, the rivers leave Yarnton alone.
Surface water is a different matter. It is rain that has nowhere to go, pooling on roads and in low gardens when the drains can't keep up, and it ignores the river zones entirely. It is the main reason Yarnton's postcode flags look busier than its zone map. The Environment Agency's long-term flood risk service lets you enter the exact address and see the surface-water rating for that property, and on a street of post-war semis that is quicker than reading anything else on this page.
Allowing for climate change, the Environment Agency's adjusted flood zone takes in about 5% of the village's postcodes. That zone is drawn on a projection of wetter decades to come. It counts for planning decisions and longer mortgages, and today it covers only a small edge of Yarnton.
Insurers price the individual property, and in a village like this most of them will look harder at a surface-water flag than at the river zones. A home clear on every measure should be routine to insure. A home with a high surface-water rating can still get cover, but the quote and the excess are where that rating turns up.
The postcode indicators fold surface water in alongside rivers and sea and record the worst rating each postcode gets on any of several measures. On that basis, about 14% of Yarnton's postcodes rate high on at least one, about 24% medium and about 42% low. These are shares of postcodes flagged on any measure, so they overlap and run higher than the zone figures by design. The gap between an empty zone map and one postcode in seven flagged high is the reason this answer is longer than one sentence.
The Environment Agency's property-level mapping for rivers and sea lists only the two postcodes in Yarnton that carry some risk, covering 69 properties. Of those, 5 are rated high, 2 medium and 2 low. None of the high-rated properties are homes. The postcodes left out of that list carry no rivers-and-sea risk on that model.
The modelled flood extents put none of Yarnton's postcodes inside a high-probability area, either with defences in the model or without them, and none inside the low-probability undefended extent. With no extent to defend, there is no wall here for anyone to point to and no wall to fail.
The nearest tide gauge is at Portsmouth, which recorded sea level rising at about 2 millimetres a year between 1962 and 2023. That is a measured rate on the south coast, a long way downstream from an inland Oxfordshire village, and it bears on Yarnton only as background.
The flood records hold no historic flooding for Yarnton. That is good to know. It means nothing has been logged here, which is a lower bar than nothing having happened.
Yarnton's flood risk is middling. The rivers leave it alone, and the rain is the part worth checking, address by address.