Yes. Loughton has a real flood risk, and most of it does not come from the river. About a third of its postcodes rate high on at least one flood measure. Only a sliver of the town is in the river-and-sea flood zones. Surface water and the other routes water takes to a front door make up the rest.
On the Environment Agency's river-and-sea mapping, about 2% of Loughton's postcodes are in flood zone 3, the highest-probability band, and about another 2% are in zone 2, the medium-probability fringe just beyond it. The two bands do not overlap, so zone 2 can be as small as zone 3 or smaller. Most of that land is on the east side, along the Roding valley, which is marshy enough that the land by the river has mostly been left as nature reserve and open parkland. The town kept its houses away from the Roding, and that decision has held up well.
Surface water is a different problem from the river. Loughton runs downhill from the forest edge, its highest ground, towards the Roding, and Loughton Brook comes off the forest through Baldwins and Staples Ponds and crosses the middle of town on the way. Heavy rain follows the same slope. Being well away from the river says little about whether a particular road collects that runoff.
The Environment Agency's climate-adjusted flood zone covers about 5% of Loughton's postcodes. That figure models how far the zone would spread under a changing climate. It does not predict that any of those streets will flood in a given year.
Insurance follows the address. A home in a mapped flood area, or on a road that takes surface water, can cost more to insure and may come with a larger excess or narrower cover than one a few streets uphill. Get an indicative buildings-insurance quote for the exact address early in the purchase, while walking away is still cheap.
The postcode-level picture is broader because it counts any of several flood measures, surface water included. About 32% of Loughton's postcodes rate high on at least one of them, about 30% medium and about half low. One postcode can appear in more than one band, because a different measure can give it a different rating.
Counting homes is more useful than counting postcodes. The Environment Agency's rivers-and-sea mapping lists 53 Loughton postcodes with some risk, covering about 1,450 properties. Of those, 107 are at high risk, 52 at medium, 323 at low and 135 at very low, and 88 of the high-risk properties are homes. Postcodes with no river or sea risk are left off the list, so those 107 are spread across only a small part of town.
About 2% of Loughton's postcodes sit in the high-risk extent with no defence in the model, and about 1% in the high-risk extent where the model includes one. "Defended" here means the model records a defence, a wall or bank of some kind. It says nothing about how that defence will cope on the day, and a seller who calls the house defended is quoting that same model.
Flood risk is Loughton's weakest point. The river side is small and well mapped, while the wider surface-water risk is spread through the town and has to be checked one address at a time.