Romsey carries a real flood risk, but a contained one that lands on a minority of the town rather than the whole of it. This is a river town, built on and around the Test, and rivers do what rivers do. The great majority of homes here sit on ground that stays dry. A meaningful slice near the water does not, and the difference between the two can be a single street. Flooding in Romsey is a question of exactly where you buy, not whether the town as a whole is safe.
Taking river flooding first, the picture is modest at the level of the whole town. Around four percent of Romsey falls in the medium-risk river flood zone, and a further four percent or so in the highest river flood zone, the ground closest to the Test where water goes when the river is full. That is a minority in both cases, but it is not a rounding error, and if your prospective house sits in it, the town-wide average is no comfort at all. The map that matters is the one drawn tight around the address, not the one drawn around the postcode.
Surface water, the flooding that comes from rain overwhelming drains rather than the river bursting its banks, spreads a little wider. About one in eight postcodes carry some level of the highest surface-water risk, roughly one in six some medium risk, and close to four in ten some low-level risk. Much of that low-level risk is the ordinary background hazard that most of England lives with. The higher categories are the ones worth a proper look, because surface water does not respect the neat line of a river zone and can turn up on ground that feels safely uphill.
Looking forward, the numbers drift the wrong way, as they do almost everywhere. Once the standard climate allowance is folded in, the share of Romsey in the high-risk river zone rises to about one in seven. That is the town planning for wetter decades rather than a forecast for next winter, but it is the figure a long-term buyer should weigh, because a house bought for thirty years is a house bought into that trajectory, not today's.
For insurance, the split matters more than the average. For most Romsey homes, well clear of the river and the worst surface-water patches, cover is straightforward and priced like anywhere else in comfortable Hampshire. For a home inside the higher zones, premiums climb, excesses grow, and a lender may want to see the flood history before it lends at all. The sensible move before any offer is to pull the specific address up on the flood maps and, if it is flagged, to get a quote in writing before you fall in love with the kitchen.
The verdict is that Romsey's flood risk is middling and manageable, high enough to take seriously and low enough that most buyers will never be touched by it. Treat it as a street-by-street check rather than a reason to cross the town off, and you will be fine.