Yes, in pockets, and a town called Redhill gets no protection from its name. About one postcode in ten sits in the highest river flood zone. Nearly one in five carries a high flag on at least one flood measure. A brook runs under the town centre. The answer depends on the address, and the town-wide average won't tell you which.
Start with rivers. On the Environment Agency's river-and-sea flood zones, about 10% of Redhill's postcodes fall in Flood Zone 3, the highest-probability zone. A further 6% sit in Flood Zone 2, the medium-probability fringe beyond it. The two bands don't overlap, so Zone 2 is the extra ring outside Zone 3, not a larger area that contains it. The Redhill Brook passes through the gap in the Greensand Ridge and runs mostly in a culvert under the town centre. A river that runs underground is still a river. The Environment Agency holds 32 recorded flood events for the area, the most recent in 1968, from a main river whose channel overflowed where there were no raised defences.
Surface water is the other half of the story, and the town's zone maps leave it out. It comes from heavy rain that the drains and ground can't take, rather than from a river bursting its banks. In Redhill it is folded into the postcode indicators described below, so a street well outside the river zones can still carry a surface-water flag.
The Environment Agency's climate-adjusted mapping widens the river zones to cover about 18% of postcodes. That is a modelled look at future conditions, not a prediction for any particular street. It is still the figure to hold in mind for a mortgage that runs twenty-five years.
Insurance follows the flags. A property in a high-risk band can expect insurers to ask more questions, and cover can cost more or carry a higher excess. Get an indicative quote on the exact address before paying for a survey, not after exchange.
At postcode level, and counting surface water alongside rivers and sea, about 19% of Redhill's postcodes rate high on at least one flood measure, 24% medium and 32% low. These bands overlap with the flood-zone shares above because they measure a wider set of risks, so the two sets of figures should never be added together. Each describes the town from a different angle.
Counting homes rather than postcodes gives a more concrete answer. The Environment Agency's rivers-and-sea mapping lists 2,025 properties across the 89 postcodes that carry some risk. Of those, 257 are at high risk, 148 at medium, 811 at low and 17 at very low. Postcodes with no river or sea risk don't appear in that list at all, so these are the properties that show up, not every home in Redhill.
Defences shift the picture very little. About 10% of postcodes sit inside the high-probability flood extent without defences in the model, and about 10% still sit inside it with defences included. "Defended" means a defence exists in the model. It says nothing about whether a particular house stays dry, and it should never be read as reassurance.
The nearest tide gauge is at Portsmouth, which recorded sea level rising by about 2 millimetres a year across its 1962 to 2023 record. That is a measured historic rate at a coastal station a long way from Redhill, not a forecast. For an inland town like this one, the brook and the rainfall matter far more than the Solent.
Before buying, work through these:
- Put the exact address into the Environment Agency's long-term flood-risk checker, for rivers and for surface water.
- Get an indicative buildings insurance quote on that address before instructing a solicitor.
- Ask the seller directly whether the property has ever flooded or claimed for flood damage.
- Ask the surveyor to note the property's level relative to the street and any nearby watercourse or culvert.
Flood risk is Redhill's weak spot: most homes are clear, but enough sit on the flagged ground that no buyer here should skip the checks.