Parts of it, yes, and the parts that are do not hide it. The town grew up around the River Stour and the water has never agreed to stay where the map says it should. Most homes sit outside the river flood zones entirely. A good many still pick up a rating on one measure or another once surface water is counted. This is not a town where flood risk is a technicality to tick off in the searches, and anyone treating it that way is buying blind.
Take the rivers first. On the Environment Agency's flood zone mapping, around 3% of the town's postcodes fall inside zone 3, the highest-probability band, and about 2% fall inside zone 2, the medium-probability fringe that sits beyond zone 3 rather than including it. Those are small shares, and they are exactly what you would expect of a town built up the slope from a river valley: the historic core near the water carries the risk, the twentieth-century estates on higher ground mostly do not.
Surface water is the less obvious problem and the more widespread one. Once the broader postcode indicators are counted, which fold surface-water risk in alongside rivers and sea, the picture stops looking so tidy. Heavy rain on saturated clay in a valley town does what heavy rain on saturated clay in a valley town has always done, and it does not need the Stour's permission to do it.
Looking forward, the Environment Agency's climate-adjusted mapping raises the share of postcodes in the flood zones to around 8%. That is the same town with a different rainfall assumption applied, not a prediction of any particular year, and it is roughly double the current zone footprint.
For insurance, this matters in the specific rather than the general. A property outside the zones and clear on the surface-water indicators should be unremarkable to underwrite. A property inside them is a different conversation, potentially involving a higher excess for flood claims, a loading on the premium, or a requirement to see a survey before anyone quotes. Get an indicative quote on the exact address before instructing a solicitor, not after.
At postcode level, counting anything that rates on at least one flood measure, about 23% carry a high rating, about 20% a medium one and about 41% a low one. Those bands overlap with the river zone figures rather than adding to them: a postcode inside zone 3 will also appear in the high band here. The useful reading is that roughly a fifth of the town's postcodes carry a serious flag on something, most often surface water rather than the river.
Counted as homes rather than postcodes, the Environment Agency's rivers-and-sea mapping puts 64 properties at high risk, 90 at medium and 183 at low, out of 1,109 properties in the postcodes that carry any risk at all. Postcodes with no risk do not appear in that count, so this is the affected slice of the town rather than the whole town. Forty-three of the high-risk properties are residential.
On defences, around 3% of postcodes sit inside a high-risk extent with no defence present in the model, against about 2% where a defence is present. A modelled defence is not a guarantee. It means something stands between the water and the house in the Environment Agency's assessment, not that the house is safe, and defences are specified to a design standard that events can exceed.
For sea level, the nearest long-record tide gauge is at Portsmouth, where the measured rise across the 1962 to 2023 record averages around 2mm a year. That is a recorded historic rate at the coast rather than a forecast, and Gillingham is an inland river town, so it bears on the wider picture rather than on this town's own water.
No historic flood events are recorded for the area in the data held here. That is genuinely reassuring as far as it goes, though a nil record means nothing has been logged rather than proving nothing has ever happened, and it does not cancel out what the forward-looking mapping says.
Flooding is the weakest part of Gillingham's case, and it is the one item on the list that can turn a good purchase into an expensive mistake. Check the specific address on the Environment Agency's long-term flood-risk service, get the insurance answer in writing early, and let the result decide whether the house stays on your list.