Hampton has some flood risk, and most of it has nothing to do with the river. The Thames flood zones barely touch the place. Surface water is a different matter. A few hundred homes carry a mapped risk, and a third of those are rated high. It is a minor problem across Hampton as a whole and a serious one in the streets it affects.
The Environment Agency's river and sea flood zones cover very little of Hampton. Less than 1% of postcodes are in Flood Zone 3, the highest-probability band, and less than 1% are in Flood Zone 2, the medium-probability fringe beyond it. The two bands do not overlap, so neither figure includes the other. The Saxons built the original village around the hillock where St Mary's Church stands, and the river maps still back that choice.
Surface water is a bigger problem than the river. It comes from heavy rain that drains cannot take away, and the river zones do not measure it at all. Hampton's postcode indicators include it, which is why they come out much worse than the zone figures. The Environment Agency has four recorded flood events here, the latest in January 2003, when a main river overflowed its channel with no raised defences to hold it. The area's first flooding trouble came from Charles I's canal, dug in 1638 and 1639 to bring water to the palace and so badly built that it flooded.
The Environment Agency's climate-adjusted mapping puts about 2% of postcodes in the river and sea flood zones once projected changes are allowed for. That is still a small share, and it reaches more of Hampton than today's zones do.
Insurers price each house on its own risk and ignore the average for the area. A home in one of the mapped high-risk spots can cost more to insure, or come with a bigger excess, than a house a few streets away on higher ground. Ask for an insurance quote on the exact address early, while pulling out costs nothing.
Counting every flood indicator, surface water included, about 14% of Hampton's postcodes rate high on at least one measure, about 24% medium and about 47% low. Those bands overlap the river and sea zones above, so the two sets of figures cannot be added together. One describes the river. The other counts any postcode where water of any kind could collect.
The Environment Agency's rivers and sea mapping lists 307 properties in Hampton, and only postcodes with some risk appear on it at all. Of those, 125 properties are at high risk, 85 of them homes, 33 at medium risk, 95 at low and one at very low. A count of 125 tells a buyer far more than a percentage does, because the only thing that matters is whether the house being viewed is on the list.
Defences make little difference to the numbers. Less than 1% of postcodes fall inside the high-risk flood extent where no defence is modelled, and less than 1% where one is. "Defended" means a defence appears in the Environment Agency's model. Whether it would hold back the water at any particular house is a separate question.
The nearest tide gauge is at Portsmouth, which recorded sea level rising by about 2 millimetres a year between 1962 and 2023. That is a past rate measured on the south coast. Hampton is a long way from the nearest tide gauge, and its flood risk comes mainly from rain.
Overall, Hampton's flood risk is middling. The river poses little threat to most of the town, but a known list of homes sits in places where surface water collects in a downpour.