Why Britain keeps building houses on flood plains

After every major flood, the aerial photographs produce the same question: who allowed those houses there? The answer is not a scandal in the singular but a system working to its incentives, and the incentives have proved remarkably resistant to wet winters.

The scale is documented. Analyses of planning data have repeatedly found that roughly one in ten new homes in England is built in flood-risk zones, with tens of thousands granted in areas of the highest risk over recent years. This is not ignorance. Flood maps are public, the Environment Agency comments on applications, and developers commission flood-risk assessments. Building happens anyway because the rules permit it: national policy allows development in risk zones where a sequential test finds no reasonable alternative site and mitigation is proposed. In districts under fierce housing targets, whose flattest, cheapest, least-contested land is often the valley floor, the tests are passed with a regularity that tells its own story.

Mitigation is where paper and water diverge. Raised floor levels, attenuation ponds and sustainable drainage genuinely reduce risk to the new homes themselves, though their maintenance decades later is nobody's clear duty. What they do less well is protect anyone else: hard surfaces and displaced water alter flows for existing neighbours, and the agency's advisory role means its objections can be, and sometimes are, overridden by local authorities. The developer's exposure, meanwhile, ends at sale.

The buyers who inherit the risk

The sharpest fine print concerns insurance. Flood Re, the industry-government scheme that keeps cover affordable for flood-prone homes, deliberately excludes properties built since 2009, precisely to avoid subsidising new flood-plain construction. The logic is impeccable and the consequence is quiet: buyers of a new-build in a risk zone stand outside the safety net, facing market-priced premiums or refused cover, a fact disclosed nowhere in the show-home literature. Conveyancing searches list flood risk, but by that stage most buyers are emotionally and financially committed.

Climate change tightens every screw. Rainfall intensity is rising, and a location assessed as safe against yesterday's hundred-year event may meet that event rather more often. Official adaptation reviews have said plainly that development in flood-risk areas continues at a pace the country's defences and drainage were not designed to absorb.

The reforms repeatedly proposed form a short list: give the Environment Agency stronger standing, make drainage approval mandatory before building, extend insurance rules to price risk visibly at purchase, and count whole-catchment effects rather than site-by-site promises. Until some of that list becomes law, the aerial photographs after the next flood will need no new caption.