Parts of Melksham are, and which part you buy in matters far more than the town as a whole. Only a small share of postcodes fall in the river flood zones. Nearly one in five is flagged high risk on at least one flood measure. The River Avon runs straight through the middle. A town-wide average won't tell you what happens on your particular street.
The Environment Agency's river-and-sea flood zones put about 2% of Melksham's postcodes in Zone 3, the highest-probability band, and about 3% in Zone 2. The two don't overlap: Zone 2 is the medium-probability strip beyond Zone 3, so it adds to it rather than containing it. The Environment Agency also lists 32 recorded flood events for the area. The most recent was in March 1978, when a blocked culvert pushed a main river out of its banks. That was a drainage failure, not a freak storm, and drainage is the kind of thing nobody inspects until it goes wrong.
Surface water, the rain that collects when drains and ground can't keep up, doesn't get its own figure here. It's folded into the postcode-level measure further down, and it's the main reason that measure runs well ahead of the river zones. Flood zone maps concentrate on rivers. Rainwater ignores the maps.
For a look ahead, the Environment Agency's climate-adjusted mapping puts about 5% of postcodes in the flood zones. That's a modelled planning allowance, not a prediction for any particular year. It's the share the planners are already designing around, which is reason enough for a buyer to pay attention to it.
Insurance follows the address, not the town. A home outside every zone and indicator should be insured on ordinary terms. A home on a high-risk postcode may face higher premiums, a larger flood excess or questions the insurer wants answered before it quotes. Flood Re, the scheme that helps insurers cover higher-risk homes, doesn't apply to homes built since 2009, so a new-build on a flagged postcode needs particular care. Get an indicative quote before instructing a solicitor, not after exchange.
On the postcode-level measure, which combines rivers, sea and surface water, 18% of Melksham's postcodes are rated high on at least one flood measure, 22% medium and 50% low. Because a postcode only needs one flag to count, these bands overlap with the river-zone figures above. They measure something different and shouldn't be added to them.
Counting homes rather than postcodes changes how it feels. The Environment Agency's rivers-and-sea mapping lists 1,650 properties in Melksham postcodes that carry some risk. Of those, 113 are at high risk, 165 at medium and 292 at low. Only postcodes with some risk appear in that list at all, so it describes the exposed parts of town, not the whole of it.
Defences barely move the modelled picture. About 2% of postcodes sit in the high-risk flood extent with defences left out of the model, and about 2% with them included. "Defended" only means a defence exists in the model. It doesn't mean water stops at the garden wall, and here it makes almost no difference to where the modelled flooding reaches.
The nearest tide gauge is at Portsmouth, where sea level has risen at about 2 millimetres a year over records from 1962 to 2023. That's a measured historic rate at a distant coastal gauge, not a forecast for Melksham. The town's exposure comes from the Avon and the rain, not the sea.
Flood risk is one of Melksham's weak spots: concentrated rather than widespread, but real on the streets it affects. Buy after checking the exact address, not the town.