Bow has some flood risk, but very little of it comes from the river. Almost the whole district is outside the river-and-sea flood zones. About one postcode in eleven rates high on at least one flood measure. The last recorded river flood was in the 1940s. In Bow it's heavy rain that causes the trouble, and the River Lea mostly stays in its banks.
On the Environment Agency's river-and-sea flood zones, about 3% of Bow's postcodes are in Flood Zone 3, the highest-probability band, and less than 1% are in Flood Zone 2. That second band is the medium-probability fringe beyond Zone 3, so it can be the smaller of the two. Within E3, the Lea runs along the eastern edge and the Limehouse Cut and the Regent's Canal run through it, and on this map the water mostly stays in them.
Surface water is the flooding that matters more in Bow: rain that falls faster than the drains can take it. It doesn't show up in the river zones at all. The flood record leans the same way. The Environment Agency has 13 recorded flood events in the area, and the most recent was in December 1947, when a main river overflowed a channel that had no raised defences. About 1% of Bow sits in places flooded at some point in that record.
Looking ahead, about 9% of Bow's postcodes fall within the flood zone the Environment Agency draws to allow for climate change. That is a modelled future, but it is the figure an insurer or a long-term lender will look at.
For insurance, most of Bow is ordinary. Postcodes in Zone 3 or with a high surface-water rating can pay more or face tougher questions, and a ground-floor flat feels that more than one on the fifth floor. With a flat, the building insurance is usually arranged by the freeholder, so the policy that matters is theirs. The useful check here is to ask for the block's insurance schedule and any flood claims on the building. The Environment Agency's long-term flood risk service will rate the exact address.
On the wider postcode measure, which counts a postcode if it rates on any of several flood indicators, surface water included, about 9% of Bow's postcodes rate high on at least one, 12% medium and 30% low. That overlaps with the river zones without matching them. Most of the extra comes from rain.
The Environment Agency also counts homes, and its rivers-and-sea mapping lists 1,273 properties in Bow, all of them in the 42 postcodes that carry some river or sea risk. Of those, 541 are rated high risk, 420 of them homes. Another 34 are medium risk, 55 low and 302 very low. Postcodes with no river or sea risk don't appear in this count at all, and that covers most of Bow.
About 2% of Bow's postcodes fall inside the high-risk flood extent with defences left out of the model, and about 2% with them put in. "Defended" only means a defence appears in the model, so it is no promise that the house stays dry. In the high-risk area the defences make no difference to how many postcodes the extent covers.
The nearest tide gauge with a long record is Portsmouth, and it measured sea level rising by about 2 millimetres a year between 1962 and 2023. That is the rate recorded at a gauge on the south coast, a long way downstream of anything in Bow.
Bow's flood risk is middling. A few streets near the water carry real risk, and on the rest of the district it's heavy rain that makes the difference.