Yes, Rush Green has some flood risk, and most of it comes from the sky more than from a river. Only a small share of postcodes sit in the river flood zones. Once surface water is counted, about one postcode in five rates high on some measure. The Environment Agency already counts more than a hundred homes at high risk from rivers. And the climate-adjusted map is several times the size of today's.
On the Environment Agency's river-and-sea flood zones, about 3% of Rush Green's postcodes are in Zone 3, the highest-probability band, and about 5% more are in Zone 2, the medium-probability fringe beyond it. The agency holds 13 recorded flood events for the area. The latest, in June 2016, came from a main river overtopping a channel with no raised defences. That is a small footprint on the map, though it is the same one that flooded within the last ten years.
The river zones leave out rain that cannot drain away. Rush Green is a built-up suburb of roofs, roads and drives, and surface water is a separate risk from the rivers, mapped separately. It is why the wider postcode measure further down comes out far higher than the zone shares.
Looking ahead, about 13% of postcodes fall inside the Environment Agency's climate-adjusted flood zone, the area expected to flood once a changing climate is allowed for. The map gets bigger over the life of a typical mortgage.
For insurance, a property in Zone 3, or one with a recorded flood, can find premiums higher and excesses steeper, and some insurers may decline it. A house on high ground a few streets away may notice nothing. Get a quote on the exact address early, before the survey money is spent, because the insurer's answer is the one that decides what owning the house costs.
On a broader measure that takes the worst of several indicators, surface water included, about 20% of Rush Green's postcodes rate high on at least one, about 27% medium and about 48% low. A postcode counts if any one of those measures flags it, which is why the share runs well past the river zones. A house can be outside every river zone and still be on that high list.
In homes, the Environment Agency's rivers-and-sea mapping lists 2,008 properties across the postcodes that carry any risk at all, and only those postcodes appear. Of them, 115 are at high risk, 204 medium and 710 low, and 33 of the high-risk properties are homes. A share of postcodes sounds abstract until it is someone's ground floor.
The same mapping puts about 3% of postcodes inside the high-probability flood extent with no defence modelled, and about 3% inside it with a defence present. A modelled defence means something stands in the way of the water in the agency's calculations. It does not mean the water stays out, and the 2016 flood came over a channel with nothing raised along it. "Defended" on a map is a line in a model, and buyers should read it that way.
Rush Green's flood risk is worse than average. The rivers touch a small part of the place, but surface water reaches far more of it, and a buyer should check the exact address before taking anyone's word for it.