Some, and most of it falls from the sky. Hardly any postcodes sit in the sea's flood zones. About one in eight rate high on at least one measure once rainwater is counted. Nothing on record says the town has flooded. The chalk cliffs keep the sea out, and the drains carry the rest of the load.
Start with rivers and the sea, the risk most buyers picture first. On the Environment Agency's mapping, about 1% of Broadstairs postcodes sit in flood zone 3, the highest-probability band for river and sea flooding, and none sit in flood zone 2, the medium-probability fringe beyond it. For a town that is mostly coastline, that is a low number, and the reason is geology more than engineering: most of Broadstairs sits on top of the cliff, not at the foot of it.
Surface water is the risk that matters here. Heavy rain that can't drain away fast enough collects in dips, underpasses and the bottom of slopes, and it doesn't care how far the house is from the beach. The postcode figures further down fold this in, and they run well above the river-and-sea zone shares, which tells you where the actual exposure is.
Looking forward, the Environment Agency's climate-adjusted flood zone puts about 1% of postcodes inside it, barely different from today's figure. On the river-and-sea measure, the projected change for Broadstairs is small.
For insurance, the two kinds of risk land differently. Insurers price from address-level models that include surface water, so a house on a street that collects rain can attract a higher premium or an excess, even with the sea nowhere near it. A quote on the exact address before an offer goes in costs nothing and tells you more than any area average.
The postcode-level picture is where the town's risk shows up. Rated on at least one flood measure, surface water included, about 12% of Broadstairs postcodes come out at high risk, about 16% at medium and about 31% at low. These bands overlap with the flood-zone figures above and measure something wider, so they shouldn't be added to them or read as the same thing.
Counting homes gives a sharper answer than counting postcodes. The Environment Agency's rivers-and-sea mapping lists 141 properties in Broadstairs across the 10 postcodes that carry any such risk at all. Of those, 84 are rated high, 32 of them residential, with 4 at medium, 2 at low and 6 at very low. Every other property in town doesn't appear on that list, because its postcode carries no river or sea risk to report.
On defences, the model shows about 1% of postcodes inside the high-risk extent without defences and about 1% with defences present. A defence being present in the model means something stands between the water and the property on paper. It doesn't mean the property is safe, and the matching figures show the defences aren't shrinking the high-risk footprint in any way the mapping can see.
The sea is close for plenty of homes. About 30% of postcodes lie within 500 metres of the coast, the nearest just 9 metres from it, and the median postcode sits about 900 metres inland. Being near the water is the point of buying in Broadstairs, and for most addresses the cliff does the protecting.
The shoreline management plan's stated policy for this stretch is to hold the line over the next 20, 50 and 100 years, meaning the intention is to keep maintaining the existing defences. That is a plan, not a promise, and it depends on money being found at each point along the way. Buyers should read it as a direction of intent, not a guarantee.
Sea level at the nearest long-running tide gauge, at Dover, rose at about 2 millimetres a year over its record from 1961 to 2010. That is a measured historic rate, not a forecast, and it is the slow background against which every coastal policy gets written.
There is no recorded history of flooding in the area. That is reassuring. It isn't proof that water has never come through a front door here, only that none has been recorded, and surface water in particular tends to go unrecorded until someone's kitchen makes the case.
Broadstairs's flood risk is middling: the sea is mostly a view, not a threat, but surface water puts a real minority of postcodes at risk, and an address-level check before buying is worth the ten minutes it takes.