Yes, and not as a footnote. Three-quarters of the place sits in the highest river-and-sea flood zone. Apply the climate allowance and the figure becomes all of it. The sea starts about fifty metres from the nearest postcode. This is a town built on reclaimed ground behind a wall, and pretending otherwise would be the single most expensive thing a buyer here could do.
Taking the river-and-sea picture first, the Environment Agency's flood zones cover 76% of the area's postcodes in zone 3, the highest-probability band, with a further 5% in zone 2. Those two bands are exclusive rather than nested. Zone 2 is the extra medium-probability fringe sitting beyond zone 3, which is why it is the smaller of the two numbers here and why anyone adding them together to reach a comfortable conclusion has misread the map. The short version is that most of Burnham-on-Sea is inside the highest band, and the bit that isn't is mostly the ring immediately around it.
Surface water is not measured separately in a clean stand-alone share for this area, because the postcode-level indicators bundle it in with rivers and sea. What the historic register does carry is 116 recorded flood events, with about 28% of postcodes falling inside a recorded historic flood outline. The most recent logged event dates to December 1981, recorded as a sea flood caused by operational failure or breach of defence. Flat reclaimed land behind a barrier does not drain quickly, and the record reflects that.
The forward look is blunter than the current one. Once the climate change allowance is applied to the modelled flood extent, 100% of the area's postcodes fall inside the zone. Not a majority. All of them.
For insurance, this matters more than any other single fact about the town. Cover is generally obtainable, but expect the flood element to be underwritten on the specific address rather than waved through on the postcode, expect excesses on flood claims to be set higher than you are used to, and expect a lender to want the position confirmed before it commits. Get an indicative quote on the actual property before you instruct a solicitor, not after. The gap between "insurable" and "insurable at a price you were expecting" is where people here get caught.
On the postcode-level indicators, which fold surface water in alongside rivers and sea, about 6% of postcodes rate high on at least one measure, 17% rate medium on at least one, and 89% rate low on at least one. Those bands overlap with each other and with the zone figures above, so they describe the same ground from a different angle rather than adding to it.
Counted as homes rather than postcodes, the Environment Agency's rivers-and-sea mapping puts 55 properties at high risk, 45 at medium and 8,122 at low, out of 8,937 properties appearing in the listing. Four of the high-risk properties are residential. Only postcodes carrying some level of risk appear in that count at all, so it describes the exposed stock rather than the whole town.
Then the question that actually decides things. Every postcode in the area sits inside the modelled high-probability extent in the undefended scenario. Only 13% sit inside the defended one. "Defended" here means a defence is present in the model, which is a statement about engineering, not about safety, and it does not mean a house behind it is out of reach of water. What it means is that for most of the town, the modelled worst case is calculated as though nothing were standing in the way.
The coast is close enough to be a daily fact rather than a scenic one. About 43% of postcodes fall within 500 metres of the shoreline, which is a threshold the data defines rather than a claim about any particular address. The closest postcode sits about 52 metres from the coast and the middle of the range sits about 567 metres back.
Shoreline management policy for the area is hold the line across all three planning horizons, at twenty, fifty and one hundred years. That is a stated intention to maintain the defence position, not a promise, not a budget, and not a defence that necessarily exists yet at any given point. Policies of that kind get reviewed, and the reviewing is done by people with competing coastlines to fund.
For context on the direction of the water itself, the nearest long-record tide gauge at Devonport measured sea level rising at about 2.35 millimetres a year across its 1962 to 2015 record. That is a measured historical rate over that period rather than a forecast of what happens next.
Flood risk is the worst thing about living here, and it is not close. Everything else this town offers is genuine, but it is offered on ground that the mapping treats as exposed almost end to end, and that is the trade being made whether a buyer names it or not.