Long term flood risk in England: how to check it and read the result

Type a postcode into the GOV.UK service and it returns four short verdicts, one for each source of flooding the Environment Agency models. Most people read only the colour. The words around it matter more, because the service answers a narrower question than the one buyers and homeowners usually bring to it.

What the long term flood risk service shows

The service, published on GOV.UK as “Check the long term flood risk for an area in England”, gives the long term flood risk for an area, not a building. That distinction is stated on the page itself: the service “does not tell you how likely it is that an individual property will flood”. It also leaves out flooding from blocked drains and burst pipes, which are problems of maintenance rather than of rivers, rain or tide.

For each location it reports:

• a risk band for rivers and the sea;
• a risk band for surface water;
• whether the area could be affected if a reservoir failed;
• groundwater risk, where data is available;
• how climate change might raise the chance of flooding.

Since 28 January 2025 the service has also shown potential flood depths and future risk with climate change, according to an Environment Agency blog post published that day. Before that update a result said how likely flooding was but gave no sense of whether it meant a few centimetres in the garden or water through the ground floor.

The figures come from the National Assessment of Flood and Coastal Erosion Risk, known as NaFRA. When you check your long term flood risk you are reading a national model, run with the same method everywhere in England, and then cut down to the point you selected.

The four sources of flooding, one by one

Rivers and the sea. This is the oldest and best-understood part of the assessment. It accounts for existing flood defences and their current condition, which the 2024 assessment says now includes improved methods for estimating the chance of defences failing under extreme pressure. A riverside street protected by a well-kept embankment can therefore come out lower than its position suggests.

Surface water. Surface water flooding happens when heavy rain cannot drain away fast enough and runs across roads and gardens or collects in hollows. It can strike far from any river. NaFRA 2024 counts about 4.6 million properties in England in areas at risk from surface water, nearly twice the number at risk from rivers and the sea.

Reservoirs. The reservoir layer does not carry a high, medium or low band in the same way. It shows the area that could be flooded if a large reservoir failed, which is an extreme and unlikely event. Being inside that outline says something about consequence, not likelihood.

Groundwater. Groundwater flooding happens when the water table rises above the surface, usually after weeks of rain on chalk or gravel. The service shows it only “where data is available”. The 2024 assessment itself states that it does not include groundwater flooding because the evidence is insufficient, and cites earlier estimates of between 122,000 and 290,000 properties in areas at risk from it. That is a wide range, and it is honest about how little is known.

What the categories mean, as officially defined

The bands are not adjectives chosen by eye. The 2024 assessment defines each one by annual chance of flooding:

An annual chance is easy to misread. A 1 in 100 chance each year is not a promise of one flood per century. Over a 25-year mortgage the chance of at least one flood in a medium-risk area is far from negligible, because the odds apply again every year and do not reset after a flood.

The bands are also wide. “Low” covers everything from a 1 in 100 chance down to a 1 in 1,000 chance, a tenfold difference. Two neighbouring streets can both read “low” and still differ a great deal. The depth information added in 2025 helps here, since shallow and deep flooding carry very different repair bills.

NaFRA 2024: what changed and the numbers behind it

The Environment Agency published the new assessment on 17 December 2024. It was the first full update of the national picture since 2018, and the Coastal Erosion Risk Map had not been revised since 2017.

The headline figures, from the Environment Agency’s announcement of 17 December 2024:

• 6.3 million properties in England are in areas at risk of flooding from rivers, the sea or surface water.
• About 2.4 million are at risk from rivers and the sea, and about 4.6 million from surface water. The two groups overlap, so they do not add up to 6.3 million.
• The surface water figure is a 43% increase on the previous assessment. The Environment Agency attributes this mainly to better modelling, not to a sudden worsening of the weather.
• For rivers and the sea, the total stayed broadly stable, but the number of properties at the highest level of risk (greater than 1 in 30 each year) rose by 88%.
• With climate change, the total could reach around 8 million by the middle of the century, around one in four properties.
• About 3,500 properties are expected to be in areas at risk of coastal erosion up to 2055, rising to about 10,100 by the end of the century.

The full assessment, last updated on 5 August 2026, breaks the present-day figures down further. For rivers and the sea it counts 367,900 properties at high risk and 323,300 at medium risk. For surface water it counts 1,071,800 at high risk and 884,800 at medium risk.

Method changed as much as the numbers. Mapping resolution went from 50 metres to 2 metres. A four-year programme brought in around 1,000 existing local flood models, so detailed studies done for individual towns now feed the national picture. Climate change is modelled with the Met Office’s UKCP18 projections, and flood depth is available nationally for the first time.

The trade-off is that finer resolution produces sharper edges, and sharper edges invite false precision. A 2-metre grid can make a boundary look as though it runs between two front doors. The model is still a model, with uncertainty in rainfall, drainage capacity and ground levels, and the band boundary is a convenient line drawn through that uncertainty.

Check your long term flood risk in England, step by step

To check your long term flood risk, start at the GOV.UK page and enter a postcode. Then work through the result in a set order:

1. Read the rivers and sea band first, then the surface water band. They are separate results. A “very low” for rivers says nothing about surface water.
2. Open the map view and move the marker to the actual building. Postcodes in rural England can cover a wide area, and the default point may sit some distance from the house in question.
3. Look at the depth information. A high chance of shallow flooding on a road is a different problem from a medium chance of deep water across a garden.
4. Switch on the climate change view. For a home bought on a long mortgage, the mid-century picture is arguably more relevant than the present-day one.
5. Check the reservoir layer and note whether the property sits in a possible reservoir flood outline.
6. Ask for the flooding history. GOV.UK offers a separate request to find out whether the area has flooded before, which the long term service does not show.

The planning flood risk map is a different tool, and mixing the two is the most common mistake. The Flood Map for Planning shows flood zones for rivers and the sea and, in its first pass, ignores flood defences. The government’s planning guidance, last updated on 17 September 2025, gives the reason: the long-term funding, maintenance and renewal of defences is uncertain. A home can therefore sit in Flood Zone 3 on the planning flood risk map and still show a low long term rating because a defence protects it. The guide to flood risk maps sets the tools side by side.

How to read a result before buying or insuring a home

A worked example shows how the pieces fit. Take a terraced house built in the 1930s on a slope above a small river, with the street running downhill towards it. The result reads “very low” for rivers and the sea, because the house is well above the floodplain. It reads “high” for surface water, because rain running off the hill collects at the bottom of the street. The depth layer shows mostly shallow water on the carriageway, with deeper pockets at the lowest point.

A buyer reading only the first line would relax. A buyer reading the whole result would ask different questions: where is the front threshold relative to the road, are there air bricks at pavement level, has the road flooded before, and does the seller’s property information form mention any past flooding? Those answers decide whether the “high” surface water band matters for this particular house.

The same result feeds into insurance. Insurers use their own models and claims data, and the Environment Agency states plainly, in section 1.8 of the 2024 assessment, that NaFRA “was not developed or tested for insurance underwriting or setting insurance premiums”. Some insurers will price the street as risky anyway. Because the house was built before 1 January 2009 and is a private home, it would meet the core Flood Re eligibility rules, which lets an insurer pass the flood part of the policy to the scheme at a price set by Council Tax band. The guide to home insurance in flood risk areas covers that step in detail.

Two cautions apply before relying on any rating:

• A low rating is not a guarantee. Flooding from blocked drains, burst pipes or overwhelmed sewers falls outside the service.
• A high rating is not a verdict on the building. It describes the area. Floor levels, construction and resilience measures can change the outcome for one house.

Limits worth knowing before you rely on the result

The long term flood risk service is built for a national, consistent view. That is its strength and its main limit. It cannot know that one house has a raised floor and the next one does not, or that a culvert at the end of the road is often blocked with leaves.

Groundwater is the weakest layer, as the Environment Agency itself acknowledges. In chalk valleys in southern England, where groundwater flooding can last for weeks, a homeowner may learn more from the parish council and long-standing neighbours than from the map.

The service also speaks only for England. A cross-border buyer in the Welsh Marches or near the Scottish Borders needs the Natural Resources Wales or SEPA maps for the other side, and those use different probability bands. More on the four nations is in the UK flood risk overview.

The climate projection is a single central view, not a forecast for a particular year. The figure of around 8 million properties by mid-century depends on the emissions path, and the assessment presents it as an estimate. It is still the best available signal for anyone deciding where to live for the next 30 years.

One last practical point concerns warnings. The long term service and the Check for flooding service are different things. The second shows live flood warnings and alerts, river and sea levels, and the flood risk for the next five days. Floodline, the Environment Agency’s 24-hour phone line, is on 0345 988 1188. A home in a high-risk area is worth registering for warnings regardless of what the insurer says, because the warning is what gives time to move a car, lift furniture or put flood boards in place.

How the UK spreads the cost of the floods that do happen, through private insurers and a reinsurance pool rather than a state scheme, is set out on the European schemes hub alongside France, Spain and Norway. The technical vocabulary of flood mapping is collected in the disaster risk glossary.