Mostly no, and where the answer turns to yes it is the rain rather than the sea doing it. Only a sliver of the city falls inside the mapped river and sea flood zones. Around one postcode in ten carries a high rating on at least one flood measure. A fifth sit within a short walk of open water. This is a city that gets wet from above far more reliably than from below, and the map that scares people is rarely the one that matters.
Start with rivers and the sea, because that is the mapping every solicitor pulls first. About 2% of the area's postcodes sit in the Environment Agency's flood zone 3, the highest-probability band, and about 1% sit in zone 2. Those two bands are exclusive rather than nested: zone 2 is the additional medium-probability fringe lying beyond zone 3, which is why it can honestly be the smaller of the two figures. For a city wrapped around two estuaries and a sound, that is a remarkably small footprint, and it is because most of Plymouth was built up the hill rather than along the water.
Surface water is the real mechanism here. Rain that arrives faster than the drains can take it does not respect a river map, and the only cause recorded against this area's flood history is local drainage and surface water. A property can sit nowhere near a flood zone and still take water off a road, a hill or a blocked gully, which is why the broad postcode indicators run so much higher than the river and sea zones do.
Looking forward, the Environment Agency's climate-adjusted zone extends to about 7% of postcodes. That is the allowance for a wetter, higher-sea-level future rather than a description of today, and it is the number worth checking if the plan is to still own the place in thirty years.
For insurance, the practical consequence is that the answer is address-specific and the quote is the honest test. A postcode-level map will not tell an insurer what it wants to know, and premiums, excesses and the availability of cover at all can differ between two houses on the same street. Getting an indicative quote before instructing a solicitor costs nothing and occasionally changes the offer.
Across the whole area, about 10% of postcodes rate high on at least one flood measure, about 12% rate medium and about 32% rate low. That indicator folds surface water in alongside rivers and the sea, so it overlaps with the zone figures rather than adding to them. Reading the two sets as separate risks and stacking them is the single most common way people talk themselves out of a perfectly sound purchase.
Counted as homes rather than postcodes, the Environment Agency's rivers and sea mapping lists 7,318 properties carrying some level of risk, of which 1,090 are at high risk, 420 at medium and 786 at low, with the rest very low. Only postcodes carrying some risk appear in that listing at all, so this is the affected slice of the city rather than the city.
The more useful split is whether anything stands between the water and the house. About 2% of postcodes sit in a high-probability flood extent with no defence in the model, against about 1% where a defence is present. Present in the model means exactly that. It is not a promise the defence is maintained, adequate for the event that turns up, or protecting the specific building.
The water is genuinely close. About 20% of postcodes lie within 500 metres of the coast, a threshold the data sets rather than a judgement about any address, and the median postcode sits roughly 1,300 metres back. Some reach the shoreline itself.
Every postcode here is covered by a shoreline management plan, and the stated policy across the twenty, fifty and hundred year horizons is to hold the line. That is an intention to maintain defences over those periods. It is not a guarantee of funding, and it is not evidence that a defence already exists in front of any particular property.
At the Devonport tide gauge, which holds records from 1962 to 2015, sea level rose at a measured rate of about 2.35 millimetres a year. That is what the record shows over that period rather than a forecast of the next one.
No postcode in the area falls inside a mapped historic flood outline, which is genuinely reassuring as far as it goes. The recorded-events log carries five entries, the most recent in December 2012. Nothing recorded is not the same as nothing happened, and the absence of an entry has never yet kept water out of a cellar.
Flood risk in Plymouth is middling: small where the maps are strict, larger where rainfall and drainage do the work, and highly dependent on which side of a hill the house sits. Check the exact address on the Environment Agency's long-term flood risk service before anything else, because the city-wide answer is comforting and the street-level answer is the one being bought.