Gillingham's flood risk is real, and it sits along the water, not across the whole town. Most postcodes are outside the river-and-sea flood zones. A small slice is in the highest-risk zone. Some homes sit within a short walk of the shoreline. The long-term plan for that shoreline changes over time. The town is mostly fine, so the thing to check is the address.
On the Environment Agency's river-and-sea mapping, about 5% of the area's postcodes are in Flood Zone 3, the highest-probability band, and about 1% are in Flood Zone 2. The zones don't overlap. Zone 2 is the medium-probability fringe beyond Zone 3, which is why it can be the smaller number. These figures cover rivers and the sea only. Surface water is measured separately.
No separate surface-water share is published for the town. It's folded into the postcode indicators below, which is where to look if heavy rain on a hard, built-up street is the worry.
Looking ahead, about 9% of postcodes fall inside the Environment Agency's climate-adjusted flood zone. That's the zone redrawn with an allowance for future conditions, and it's a forward-looking planning line, not a record of anything that has happened.
For insurance, a home inside a flood zone or near the shoreline can expect insurers to ask more questions and, in some cases, charge more for cover. Get a quote for the exact address before you commit to a sale. A listing will describe a waterside home by its view. The insurer will describe it by its postcode.
The postcode indicators fold surface water in with rivers and sea. About 12% of postcodes rate high on at least one flood measure, 16% medium and 37% low. These bands overlap with the flood-zone shares above. They're a different measure, and you can't add the two together.
The Environment Agency's rivers-and-sea mapping also counts properties, which is the more useful figure. Across the 173 postcodes that carry some risk, it lists 4,441 properties. Of those, 529 are at high risk, 318 at medium, 2,281 at low and 847 at very low. Of the high-risk properties, 464 are homes. Only postcodes with some risk appear in these counts, so the rest of the town isn't in them at all.
On whether anything stands between the water and the house: about 5% of postcodes sit in the high-risk extent with no defence in the model, and less than 1% sit in it with a defence present. "Defended" means a defence appears in the model. It doesn't mean the property is safe, and it isn't a promise. A word that sounds like a guarantee is doing the work of a footnote.
The water is close for some. About 15% of postcodes are within 500 metres of the coast, the nearest just 6 metres away, and the median postcode is about 1,480 metres from it. The 500-metre line is a threshold, not a verdict on any particular house.
The shoreline management plan for this stretch sets a policy of holding the line for the next 20 years, meaning the stated intention is to maintain the existing defences. Over the 50-year and 100-year horizons, the policy switches to managed realignment, which allows the shoreline to move back in a controlled way. A policy is an intention, not a guarantee, and it isn't a wall. Buyers on a 30-year mortgage should read which horizon their house falls under.
The nearest tide gauge, at Dover, recorded sea level rising by about 2 millimetres a year over its record from 1961 to 2010. That's a measured historic rate, not a forecast.
No recorded historic flooding appears for the area. That's reassuring, but it's a statement about records, not proof that water has never come in.
Gillingham's flood risk is middling. The town away from the water is largely clear, and the homes on or near the shoreline are the ones that need a close look.