England’s flood defences: what the NAO found

If you are buying, building or insuring property, that gap is the part that matters. A defence drawn on a map is not the same as a defence that holds when the river comes up, which is why a site-specific flood risk assessment still does work that a national flood map cannot.

What the NAO and the Public Accounts Committee actually found

The findings were stark, and they have not aged well. Government committed £5.2 billion to roughly 2,000 new flood schemes between 2021 and 2027, with a headline target of better protecting 336,000 properties and avoiding about £32 billion of wider economic damage. By the time the auditors reported, that forecast had fallen to 200,000 properties — a cut of more than 40 percent — and around 500 of the planned projects had been dropped.

Inflation took most of the official blame, accounting for between half and two-thirds of the shortfall. It is not the whole explanation. Inflation does not account for the Environment Agency underspending its flood budget in the early years of the programme, when the funding was available and the risk was rising, nor for the roughly 500 schemes that were dropped or the smaller projects held up in the approvals process. The Public Accounts Committee went further, concluding that the department lacked a clear view of its own progress and could not say with confidence what its spending was achieving. Those are questions of planning and financial management, and they rest with the Environment Agency as much as with the wider economic climate. We made a similar argument when the report first appeared, in flood resilience in England: a wake-up call. The concern is not new, either. The same issues recur over the years, as the Pitt Review and its unfinished business shows.

It also helps to be clear about who is accountable for what. Flood risk in England is shared between several bodies, and the Environment Agency’s role in flood risk and planning sits alongside lead local flood authorities, water companies and councils. We set out the full picture in our guide to who is responsible for managing flood risk.

Protected on paper, vulnerable in practice

The number that should worry homeowners is not the one about new schemes. It is the maintenance backlog. The NAO found around 203,000 properties at increased risk because the defences meant to protect them have been allowed to deteriorate — more properties than the entire capital programme expects to better protect by 2027. The Agency also missed its own target of keeping 98 percent of its high-consequence assets in good condition. Government later admitted it had inherited defences in the worst condition on record, and redirected £108 million to urgent repairs to stop the slide. Allowing existing defences to fall below standard while running a record capital programme is a difficult position to defend, and it was central to the auditors’ concerns.

This is the bit people find counter-intuitive. A wall, embankment or barrier can exist, appear on a map, and still not perform to the standard it was designed for. We dug into this in below-standard flood defences: protected on paper, vulnerable in practice, and it is also why so many owners ask why they are still in a flood zone after new defences were built. A defence reduces risk. It rarely removes it.

Bigger budgets, unanswered delivery questions

The funding picture has improved markedly, and credit where it is due. The Spending Review reset the numbers upward. According to GOV.UK, the government will invest more than £10.5 billion in flood defences by 2035/36 — the largest flood programme in the country’s history — projected to benefit over 890,000 properties. That figure combines a two-year £2.65 billion settlement to March 2026 with a £7.9 billion, ten-year commitment from 2026/27 aimed at protecting 840,000 homes and businesses. In its first year the programme delivered 151 schemes and better protected more than 24,000 properties, with the total expected to pass 52,000 by April 2026. We have covered the detail in Defra’s £10.5bn funding overhaul, the £7.9bn infrastructure commitment and the £1.4bn confirmed for 2026/27.

The way the money is shared out has changed too. From April 2026 a new FCERM funding framework fully funds prioritised projects worth £3 million or less and puts natural flood management on the same footing as concrete and steel — the biggest reform to floods funding in fifteen years. There are even signs the governance is tightening: the NAO later gave Defra its first clean audit opinion since 2018/19, after years of qualifications over how the Agency valued its assets.

It would be easy to read all that as problem solved. It is not. The NAO warned that the pressure to hit a headline figure can push a programme towards rushed decisions and cost overruns, and a larger budget makes that risk bigger, not smaller. More than six million properties in England are at risk today, and that figure is expected to climb towards one in four by 2050. Money buys less than it once did, large schemes still slip — the delays to the River Thames Scheme are a case in point — and a defence that is funded protects nobody until it is built and then kept in good repair. The commitment is welcome. The harder task, on the auditors’ own evidence, is turning that commitment into protection on the ground.

What the defence gap means for you

For developers, the practical lesson is simple: do not let a nearby defence do your thinking. National mapping shows broad probability, not what happens on your plot. A robust flood risk assessment for planning still has to account for breach and overtopping, climate change allowances, finished floor levels and safe access, and where a site is constrained that often means sequential and exception test work or site-specific flood modelling rather than a reading off the published map.

For buyers, a defended location is not a risk-free one. If a search has flagged a property, an independent flood risk survey for property purchase tells you what the broad datasets cannot: how flooding would actually affect that building, and whether the price reflects the risk. For owners and insurers the same logic applies. Premiums are rising, and Flood Re — the scheme that keeps cover affordable in higher-risk areas — is temporary and due to end in 2039. A property-specific flood risk assessment for insurance can support better underwriting decisions where automated screening falls short.

Where Unda fits

Public defences are improving, but the honest position is that no household or developer should rely on them alone while protection still lags behind the risk. We help clients see the real, site-specific picture rather than the reassuring average.