Mostly no, but the River Kennet runs through the middle of town, so the answer changes from one street to the next. Only a sliver of the town sits in the highest river flood zone. About one postcode in ten gets a high flag on at least one flood measure. There are no recorded historic floods in the area. For most homes the risk is low. For some it is not.
On the Environment Agency's river-and-sea flood zones, about 1% of Marlborough's postcodes fall in zone 3, the highest-probability band. About another 5% fall in zone 2, the medium-probability fringe beyond it. The two bands don't overlap: zone 2 is the extra ground outside zone 3, not a larger area that contains it. Everything else is in zone 1.
There is no separate surface-water figure for the town. Rain overwhelming drains and running downhill is folded into the postcode indicators below, and it is the reason those indicators run higher than the river zones.
The Environment Agency's climate-adjusted zone, its forward look at how river flooding could spread as the climate changes, covers none of the town's postcodes at present. That's a projection from modelling, not a promise.
For insurance, the question is whether the exact address is mapped at risk, not whether the town as a whole is. A home in zone 1 with no surface-water flag should be quoted normally. A home in zone 3, or one flagged high for surface water, can expect insurers to ask more questions and possibly price accordingly. Get a quote before you are legally committed to buying.
Taking every flood measure together, including surface water, about 11% of postcodes are high risk on at least one of them, about 15% medium and about 31% low. These bands overlap with the river zones, so they cannot be added to the zone figures. They answer a wider question: does anything put this postcode at risk?
Counted as properties rather than postcodes, the Environment Agency's rivers-and-sea mapping covers 673 properties in the 28 postcodes that carry any risk. Of those, 18 are high risk, 17 of them homes, and 79 are medium risk. A further 248 are low and one is very low. Postcodes with no river or sea risk are left out of this count entirely, so the total is the at-risk end of town, not the whole of it.
In the modelled flood extents, about 2% of postcodes sit in the high-risk area with defences left out, and about 2% sit in it with defences included. In practice, the defences in the model make little difference to how much of the town floods in the high-risk case. Where a defence appears in the model, that means one exists. It does not mean the house behind it stays dry. In the low-risk extent without defences, the share rises to about 6%.
The nearest tide gauge is at Portsmouth, where sea level rose at about 2 millimetres a year across its record from 1962 to 2023. That is a measured past rate, not a forecast. Marlborough is a river town a long way inland, so the sea is not what threatens it.
The area has no recorded historic flooding. That is good news, but it covers only what was recorded, not everything that has ever happened.
Before buying, a buyer should:
- Enter the exact address into the Environment Agency's long-term flood risk service, and check the river and surface-water results separately.
- Get an insurance quote for the specific property before exchanging contracts.
- Ask the seller, in writing, whether the property has ever flooded or made a flood claim.
- Ask your solicitor to order an environmental search that covers flooding.
Marlborough's flood risk is middling rather than serious. Across most of the town it is low, and it is concentrated in a small number of homes near the water, so the address matters more than the town's overall figures.