Some of it is, and the river decides which parts. The village sits on a river flood plain. Only a thin slice falls inside the main river flood zones. Far more postcodes pick up some risk once rainwater is counted too. A small risk, unevenly spread, so your exact address matters more than the village name.
The Environment Agency's river-and-sea flood zones put about 2% of Marden's postcodes in flood zone 3, the highest-probability band, and about 3% in flood zone 2. The two zones don't overlap. Zone 2 is the medium-probability fringe beyond zone 3, not a bigger area that contains it. The River Beult is the reason either zone exists here, since the parish sits on its flood plain. The one flood event on the agency's records dates from November 1960, when the main river overflowed a channel with no raised defences. About 1% of the area has any recorded history of flooding. And about 15% of postcodes fall under the Upper Medway Internal Drainage Board, whose whole job is keeping the low ground drained. Listings rarely lead with that.
Surface water, meaning rain that can't drain away fast enough, isn't reported here as a separate figure. It is folded into the postcode indicators further down, and that is where it shows up. A house can sit well outside both river zones and still have a problem with the lane outside it after a heavy storm.
Looking ahead, the Environment Agency's climate-adjusted flood zone takes in about 5% of postcodes. That's a modelled allowance for how the zones may widen, not a date when they will.
For insurance, any address in or near those zones should be treated as a question to answer before exchange, not after. Premiums and excesses depend on the individual property's risk and history, and a quote costs nothing while you still have the choice. The buyer who finds out after completion is paying for the lesson instead.
The postcode-level indicators take in more, because they count a postcode as at risk if it rates on at least one measure, surface water included. On that basis about 13% of postcodes rate high on at least one measure, 18% medium and 31% low. These bands overlap with the flood-zone shares above, so they can't be added together. They are a wider net, not a second helping.
Counting properties is more useful than counting postcodes. The Environment Agency's rivers-and-sea mapping lists 17 postcodes in Marden carrying some risk, holding 463 properties. Of those, 16 properties are at high risk, 7 at medium and 115 at low, and 11 of the high-risk ones are homes. Postcodes with no river or sea risk don't appear in that list at all.
Then there's the question of whether anything stands between the water and the house. None of Marden's postcodes sits in the modelled high-risk extent without a defence, while about 2% sit in it with one. About 2% more fall in the low-risk extent with no defence. "Defended" only means a defence appears in the model. It isn't a promise that the water stays out, and the 1960 flood happened exactly where raised defences were missing.
Sea level isn't Marden's direct problem, but it sets the wider direction. The nearest tide gauge, at Dover, recorded sea level rising by about 2.2 millimetres a year over its record from 1961 to 2010. That's a measured past rate, not a forecast.
Flood risk here is middling. Most of the village is clear, but the minority that isn't is real, and the only way to know which side a house falls on is to check the exact address.