Yes, Tottenham carries a real flood risk, and it reaches well beyond the riverbank. About a quarter of postcodes sit in the river flood zones. Almost three in ten register a high risk on at least one flood measure. Very few homes face the worst river risk, but the moderate kind is widespread. In a district on low ground by the Lea, much of it is wet ground waiting for a wet year.
On the Environment Agency's river-and-sea mapping, about 28% of Tottenham's postcodes fall in Flood Zone 2 and about 6% in Flood Zone 3. The two zones are separate bands. Zone 3 is the higher-probability core, and zone 2 is the medium-probability ground beyond it, so the larger zone 2 figure does not include the zone 3 postcodes. The River Lea forms the eastern boundary and has marked a border since it divided Middlesex from Essex and the Danelaw. The water has stayed on the map longer than any of the borders.
Rain is the other half of the risk. About 11% of Tottenham's postcodes have a recorded flood on file, and the Environment Agency logs 123 recorded flood events here. The most recent on record dates from December 1947, when a main river overflowed its channel with no raised defences in place. The River Moselle, a tributary of the Lea, flooded the district so often that most of it was covered over in the 19th century. A covered river still carries the same water, just out of sight under the street.
The Environment Agency's climate allowance puts about 39% of Tottenham's postcodes inside the flood zone once its projections for future rainfall and river flows are added. That is the agency's planning scenario for the decades ahead, and the share is wider than today's zones.
Insurance is where this shows up first. A home in a modelled flood zone, or on a postcode with a recorded flood, can find cover harder to arrange and more expensive, and some policies come with higher excesses for flood claims. Get a quote for the exact address early, while you can still walk away cheaply. A surprise from the insurer is cheaper before exchange than after it.
The postcode indicators take a wider view. They count a postcode if it rates on any one of several measures, surface water included, alongside rivers and the sea. On that basis about 28% of Tottenham's postcodes rate high on at least one measure, about 24% medium and about 33% low. Because surface water is included, these shares cover more ground than the river zones alone.
Counting homes gives a clearer picture. The Environment Agency's rivers-and-sea assessment lists about 13,080 properties across the 412 Tottenham postcodes that carry any risk at all, and postcodes with no risk are left out of the count. Just two of those properties are at high risk, and only one of them is a home. Another 971 are at medium risk, 3,635 at low and about 5,620 at very low. Two properties is a reassuring number for the worst case. At 971, the medium band is the one most buyers will have to think about.
Defences barely feature in the model. About 6% of postcodes fall within the high-probability flood extent with no defence modelled, and less than 1% fall in it with a defence modelled. Even where the model does show a defence, that only means one exists. It says nothing about how high it is or how well it is maintained.
The nearest tide gauge in this dataset is at Portsmouth, where sea level rose by about 2 millimetres a year across its 1962 to 2023 record. That is a long way from a north London district whose risk comes from rivers and rain, and it tells you about the coast more than about Tottenham.
Flood risk is one of Tottenham's real weaknesses. The worst case is rare, but the moderate risk reaches enough of the district that every purchase deserves a flood check.