Braintree has some flood risk, and most of it comes from rainwater with nowhere to drain, with the rivers a smaller part. About one postcode in a hundred is in the highest river flood zone. Roughly one in fourteen shows high risk once surface water is included. Only five properties have the top river-and-sea rating. Overall the risk is middling, and it is spread out across the town.
On the Environment Agency's river-and-sea flood zones, about 1% of Braintree's postcodes are in zone 3, the highest-probability band, and about 2% more are in zone 2, the medium-probability band just outside it. Pod's Brook becomes the River Brain at the western edge of town, and the Pant runs through Bocking. The Agency has 17 recorded flood events for the area, the most recent in October 2001, when a main river overflowed its channel at a point with no raised defences. The town shares its first syllable with the Brain, and on the river maps it shares very little else with it.
Surface water is the risk the river zones leave out by design. It comes from heavy rain that cannot drain away fast enough, and it can reach streets nowhere near a riverbank. In Braintree it is counted in the postcode indicators further down, and that is where most of the town's flood risk shows up.
Once the Environment Agency adds its allowance for climate change, about 4% of postcodes fall inside the river-and-sea zones. That is the Agency's estimate of where the line moves under a wetter climate, and the edge of the map is a modelled line, not a fixed one.
For insurance, being in a high-rated river zone or showing up on a surface-water map can push premiums up or limit which insurers will quote, and most Braintree addresses face neither. Put the exact address into the Environment Agency's long-term flood risk check and look at the surface-water result as well as the river one, since the surface-water result is the one more likely to catch out a house in Braintree.
Counting every measure, surface water included, about 7% of Braintree's postcodes rate high on at least one, 12% medium and 32% low. Those figures count a postcode if any one of several measures flags it, so they are always larger than the river-zone shares.
Counted as homes and other properties, the Environment Agency's rivers-and-sea mapping lists 2,000 properties in Braintree postcodes that carry some risk. Five of them are rated high, one of which is a home, 137 are medium, 253 low and 266 very low. Postcodes with no river or sea risk are left out of that list entirely. Five properties at the top rating is a short list for a town this size.
In the Agency's modelled flood extents, about 1% of postcodes are in the high-probability area with the defences left out, and the share is about the same with defences included. Removing defences from the model does not shrink the high-risk area, so in most places the defences make little difference to which homes are in it. In the low-probability extent, about 3% of postcodes fall inside before defences are counted. A defence showing up in the model only means one exists, and it says nothing about whether a particular house stays dry.
Braintree's flood risk is middling. River flooding affects a handful of properties, while surface water spreads a wider risk across the town, and that is the one a buyer should check for their own address.