Yes, from rainfall, not from rivers. The river and coastal flood zones cover less than one percent of the place. Historic recorded flooding is effectively zero. About a third of postcodes carry some high surface-water flood risk, and another three in ten carry medium risk. The story here is rain meeting estate-road drainage, not a river coming out of its banks.
The river and coastal picture is basically blank. The Environment Agency's middle flood-risk zone covers under one percent of the area, and the highest river-and-sea zone covers none of it. No historic flooding has been logged for the village itself. There is no river of any size running through, no estuary, no harbour wall to worry about. Whatever the long-term sea-level story does to the south coast, it is not going to reach a place sitting on the wooded high ground above Waterlooville.
The surface-water picture is where the actual risk lives. About a third of postcodes carry some high surface-water flood risk, and another three in ten carry medium risk. That leaves under half of the place sitting in the low-risk band. The pattern is what you get when post-war suburbia paved over a sloping forest fragment without putting in drainage that could keep up with the rainfall it is now getting. Heavy rain finds the slope, hits a road, and pools where the kerb met the front garden someone resurfaced for parking.
The climate-adjusted flood zone share comes in around 1.4 percent of the area, which is a small forward look on river and coastal flooding. It does not really capture where the risk is concentrated here. The surface-water shares already include the things that matter for Cowplain, the rainfall intensity and the geometry of the streets, and the trend is one of those numbers getting worse with every storm season rather than better. The published surface-water risk for the place tomorrow is not going to be lower than it is today.
Insurance reflects this. A house in a high surface-water risk postcode is not uninsurable, but the premium and the excess move, and the lender's surveyor will ask the question on a purchase. Flood Re, the joint-industry pool that helps with home insurance in flood-prone postcodes, does not cover homes built since 2009, which catches some of the newer infill stock around the village's edges. The right move on a specific property is to pull a flood-risk report on the address rather than trust the postcode average, and to ask the seller's solicitor what the actual claim history has been on the house itself.
The flood verdict for Cowplain is poor, and it is poor entirely on the surface-water side. The houses are not going to be washed away by a river, but the road outside about a third of them has a known problem with rainwater going where it should not, and that is the kind of risk that gets worse, not better.