Partly, and the part matters. This is the edge of the Somerset Levels, which is drained land that used to be water and has never fully accepted the new arrangement. A small slice of the town sits in the formal river-and-sea flood zones. A bigger slice carries some flood indication once surface water is counted. The town-wide answer is calm; the address-level answer is the only one worth paying for.
Start with rivers and sea. The Environment Agency's flood zones cover about 5% of the area's postcodes in zone three, the higher-probability band, and about 3% in zone two. Those two are separate bands rather than one inside the other, so zone two being the smaller figure is not an error: it is the additional medium-probability fringe lying beyond zone three, and it happens to be a thin one here. Between them they describe the low ground toward the moors, not the town as a whole.
Surface water is the risk people forget because it does not appear on the map they are looking at. There is no separate surface-water-only share published for this area, so it arrives folded into the broader postcode indicator further down. It is worth naming anyway, because surface water is what puts water through a door on a street that no river runs anywhere near, and it is the flooding that most often surprises a buyer who checked one map and stopped.
Looking forward, the Environment Agency's climate-change allowance pushes the zone coverage to roughly 12% of postcodes. That is a modelled future rather than a forecast of any particular decade, and it is the number a buyer holding a house for twenty-five years should be reading rather than the present-day one.
For insurance, a high-risk indication changes the conversation rather than ending it. Get an indicative quote on the specific address before you instruct a solicitor, ask the seller directly about past claims, and read the excess as carefully as the premium. Cover is generally obtainable in areas like this; the cost and the excess are where the risk actually shows up.
On the combined picture, about 16% of the area's postcodes rate high on at least one flood measure, roughly 13% medium and about 28% low. That indicator folds surface water in alongside rivers and sea, so it captures more than the zone shares and overlaps with them. The two sets describe the same town through different lenses and should never be stacked on top of each other.
Counted as homes rather than postcodes, the Environment Agency's rivers-and-sea mapping puts 53 properties at high risk, 31 at medium and 42 at low, out of 370 properties across the 22 postcodes that carry any risk at all. Fifty of those high-risk properties are residential. Postcodes with no risk do not appear in that list, which is why the total is a fraction of the town.
On defences, about 6% of postcodes fall inside a modelled high-risk extent with a defence present, and about 6% inside a high-risk extent without one. Present in the model means a defence exists in the modelling, not that the house behind it is safe. Defences are designed to a standard, and water does not read the design brief.
The nearest coast is roughly 2.4 kilometres away, and the shoreline management policy covering these postcodes is to hold the line across the twenty, fifty and hundred-year horizons. That is a stated intention to maintain defences over those periods. It is not a promise, it is not funded in advance, and it is not the same as a defence that already stands there.
At the nearest tide gauge, at Devonport, sea level rose by about 2.35 millimetres a year across the 1962 to 2015 record. That is measured history rather than a projection, and it is the backdrop against which the hold-the-line policy has to be delivered.
No historic flooding is recorded across the area in the brief's mapping, which is genuinely good news. It is not proof that nothing has ever come through a door here, only that nothing has been recorded in that dataset.
Flooding is the real mark against this town, and it is a geographic fact rather than a fixable one: the Levels start where the gardens stop. Most of North Petherton is dry and will stay that way, but the difference between a fine address and an awkward one here is measured in a few hundred metres and a couple of metres of elevation, so check the postcode, not the town.