Wallingford's flood risk is middling, and the Thames causes less of it than a riverside town would lead you to expect. Hardly any postcodes fall in the river's flood zones. A broader measure picks up more, because it counts rain as well as the river. A few dozen homes are rated high risk. Most people blame the river, but rain that never reaches it causes a fair share of the problem.
The Environment Agency's river-and-sea flood zones cover very little of Wallingford. About 1% of the town's postcodes are in flood zone 3, the highest-probability band. Another 4% are in flood zone 2, the medium-probability fringe outside it. Zone 2 can be the larger share because it is a separate ring around zone 3, and the two shares don't overlap. The town grew up at the lowest point where the Thames could be forded, so the people who built it knew exactly where the river ran shallow. The zone map suggests that most of the later housing kept a respectful distance from it too.
Those zones only measure water coming out of the river, so rain that pools on roads and gardens before it ever reaches the Thames is left out. That surface-water risk shows up instead in the postcode measure further down. The Environment Agency has three recorded flood events for the area, the most recent in February 2014.
The Environment Agency also publishes a version of the zones that allows for climate change, and about 17% of Wallingford's postcodes fall inside it. That is a modelled scenario of where the zones could reach under a wetter climate. Nobody can say from it which year, or which street.
For insurance, most of the town should be routine. Cover for a home inside a zone, or on a postcode flagged high, is more likely to cost more or come with conditions, and two houses on the same road can be priced quite differently. The useful step is to put the exact address into the Environment Agency's long-term flood risk service and get an insurance quote while the purchase is still at the solicitor stage.
The Environment Agency also rates every postcode on several flood measures, surface water included, and records the worst result each postcode gets on any of them. On that basis about 7% of Wallingford's postcodes rate high on at least one measure, 8% medium and 41% low. So four in ten postcodes carry some risk somewhere on the list, and much of it is the low kind that is easy to forget.
Counted as homes, the river-and-sea picture covers 438 properties, and these are only the ones in the 29 postcodes that carry some risk at all. Of those, 27 properties are rated high, 31 medium and 143 low. Thirteen of the high-risk properties are homes. That is a short list, but it matters a great deal to anyone whose house is on it.
The Environment Agency's model also shows whether flood defences are present. About 1% of postcodes are in the high-risk extent with no defence and about 1% with one. A defence existing in the model does not mean the house behind it stays dry. All it tells you is that something has been built between the river and the house.
The nearest tide gauge is at Portsmouth, where sea level rose by about 2 millimetres a year between 1962 and 2023. Rising sea level isn't the risk that matters in Wallingford.
Wallingford's flood risk is ordinary for a Thames town. It is low across most of the town and serious on a small number of addresses, and the same river runs past both.