One in Nine New Homes in Flood Risk Areas – is 11% Evidence of Planning Failure?

The insurer reports that 11% of the 396,602 new homes recorded during that period fall within areas classified as medium or high risk under the Environment Agency’s latest national flood risk assessment. A further 26% are said to have “some” level of flood risk.

The 11% figure is up from 8% previously reported for 2013 – 2022. By 2050, Aviva projects that around one in seven of these recently built homes could fall into medium or high risk categories.

At face value, that suggests a growing structural issue. But does this statistic demonstrate that flood risk planning policy is failing — or does it reflect how England is built and how risk is managed?

What does the 11% figure actually measure?

Aviva’s methodology combines Ordnance Survey AddressBase data for new homes with the Environment Agency’s most recent national flood and coastal erosion risk assessment at constituency level.

That produces a broad exposure picture. It identifies homes located in areas categorised as medium or high flood risk.

It does not show:

• whether individual sites passed the Sequential Test,
• whether the Exception Test was applied,
• how detailed Flood Risk Assessments mitigated site-specific risk,
• or how existing flood defences affect actual safety outcomes.

A national percentage provides a macro-level snapshot. It does not, on its own, demonstrate that development is unsafe.

Flood risk mapping is not the same as site safety

Flood risk in England is described through several overlapping systems:

• National flood risk assessments (used in Aviva’s analysis),
• Flood Zones used for planning (Zones 1, 2 and 3),
• Surface water flood mapping,
• And site-specific modelling within Flood Risk Assessments.

Importantly, national mapping is based on probability modelling and broad-scale data. Planning decisions, by contrast, rely on detailed, site-specific assessments that consider:

• flood defences and their standard of protection,
• breach and overtopping scenarios,
• climate change allowances,
• finished floor levels,
• compensatory flood storage,
• drainage design and Sustainable Drainage Systems.

Being located in an area classified as medium or high flood risk does not automatically mean a development is unsafe. Planning policy is structured to manage — not eliminate — risk.

England’s geography and urban form

England’s historic settlement pattern is relevant.

Many towns and cities developed along rivers and estuaries. Significant parts of existing urban areas lie within floodplains, including areas protected by major engineered defences.

If all land within mapped flood risk areas were excluded from development, substantial areas of established urban England would effectively be removed from consideration. National policy does not adopt that approach. Instead, it applies a risk-based framework.

How flood risk planning policy is designed to work

National planning policy applies the Sequential Test, intended to steer development to areas of lowest flood risk first.

Where development in higher risk areas is necessary, the Exception Test requires that proposals demonstrate:

• the development will be safe for its lifetime,
• it will not increase flood risk elsewhere, and
• it should reduce overall flood risk where possible.

In 2024 / 25, 96% of planning decisions complied with Environment Agency advice on flood risk, and 99% of proposed new homes in planning applications complied with that advice.

Those compliance rates suggest the procedural framework is being followed. Whether that translates into optimal long-term resilience is a more complex question.

The increase from 8% to 11%

Aviva previously reported that around 8% of new homes built between 2013 and 2022 were located in Flood Zone 3, which is defined using undefended probability thresholds.

The new 11% figure is derived from a different dataset — the Environment Agency’s latest national flood risk assessment — and is not limited solely to Flood Zone 3.

That distinction matters. It means the two percentages are not strictly like-for-like comparisons, even if they indicate an upward trend in development exposure.

The broader concern about increasing risk exposure and climate projections was discussed in more detail in Planning is falling behind flood risk, says Aviva.

Whether the rise reflects:

• intensified housing delivery in constrained authorities,
• redevelopment within existing urban floodplains,
• growing spatial pressure,
• or genuine policy dilution,

cannot be determined from a national percentage alone.

Does better data resolve the planning question?

A second framing has emerged in response to the Aviva figure: the headline reflects better visibility of risk, not more flooding, and the planning system already manages risk through site-specific assessment. There is something to that argument. The Environment Agency’s August 2025 update to the Flood Map for Planning, the move to NaFRA2’s higher-resolution surface water modelling, and the integration of Ordnance Survey and Snowflake datasets all give planners and consultants a sharper picture of where risk actually sits. Modelling that no longer deflects floodwater around buildings is, plainly, an improvement.

The difficulty is that the 11% figure does not describe the data — it describes the decisions made on the back of it. Better visibility upstream of a determination does not, by itself, change how the Sequential Test is being applied at application stage, how Exception Test justifications are scrutinised, or how local plans identify reasonably available alternative sites. Recent appeal decisions — Yatton among them — have shown how thin the alternative-sites evidence base often becomes when tested, and how readily refusals on flood-risk grounds can be overturned at appeal. That is a planning-system signal, not a data signal.

This is why much of the live policy work matters. The September 2025 PPG update on flood risk and the Sequential Test tightened the test for what counts as a properly evidenced search for alternative sites. The April 2026 reforms to the planning appeals regime push some of that rigour into the appeal stage, where it has been weakest. Better data plus a tightened regime is what shifts the figure. Data on its own, as the recent record of applications consented despite flood-risk concerns shows, makes the situation more legible — it does not make it less acute.

The longer-term question: resilience and insurability

The more consequential issue may lie in long-term resilience.

Homes built after 2009 are excluded from Flood Re, the government-backed reinsurance scheme intended to support flood insurance affordability in higher risk areas. That exclusion was designed to avoid incentivising development in flood-prone locations.

If climate change increases the frequency or severity of flooding, as projections suggest, the interaction between planning policy, national risk mapping and insurance availability becomes more significant.

The sharper question may not be:

But:

So, is 11% high?

Eleven per cent of new homes in areas classified as medium or high flood risk is not negligible. But nor, in a country where much of the urban fabric sits within river corridors and coastal zones, is some level of exposure surprising.

An expectation of zero would ignore England’s geography and settlement history, and improvements in flood data alone do not change that picture.

The more meaningful assessment lies not in the headline percentage alone, but in whether the planning system — through the Sequential Test, Exception Test and detailed Flood Risk Assessments — is consistently delivering development that is safe for its lifetime and does not increase risk elsewhere.