Flood Zones in England

 

If you are trying to find out which flood zones affect your property or development site, this guide explains the system used for planning in England. Flood risk can come from rivers, the sea, surface water and other sources, so the mapped Flood Zone is only part of the picture.

The Environment Agency’s Flood Map for Planning shows Flood Zones 1, 2 and 3 for river and sea flooding. Flood Zone 3b is the functional floodplain and is normally identified by the local planning authority through its Strategic Flood Risk Assessment (SFRA).

You can establish which flood zone you are in by visiting this Environment Agency website.

Further guidance is available in the government’s flood risk and coastal change guidance and the current National Planning Policy Framework.

On the coast, flood risk is only part of the picture. Where long-term shoreline change or erosion is expected, also check whether the site is within a Coastal Change Management Area.

Flood Zones 2 and 3 on the Flood Map for Planning cover river and sea flooding. They do not take account of the benefits of flood defences or the possible effects of climate change, so other Environment Agency data and the local SFRA also need to be checked.

 

Flood Zone 1

 

Low Probability

Flood Zone 1 is land with less than a 0.1% annual probability of river or sea flooding. This is less than a 1 in 1,000 chance in any year.

Being in Flood Zone 1 does not automatically mean that flood risk can be ignored. A flood risk assessment is required for some sites, including sites of one hectare or more, land with critical drainage problems, and land identified by the SFRA or Flood Map for Planning as being at risk from any source now or in the future.

 

Flood Zone 2

 

Medium Probability

Areas deemed to be in flood zone 2 have been shown to have between 0.1% – 1% chance of flooding from rivers in any year or between 0.1% – 0.5% chance of flooding from the sea in any year.

Land having between a 1 in 100 and 1 in 1,000 annual probability of river flooding; or land having between a 1 in 200 and 1 in 1,000 annual probability of sea flooding. (Land shown in light blue on the Flood Map).

Flood zone 2 development needs to submit a flood risk assessment as part of its planning application which shows the risk of flooding to the site.

 

Flood Zone 3a

 

High Probability

Areas within flood zone 3 have been shown to be at a 1% or greater probability of flooding from rivers or 0.5% or greater probability of flooding from the sea.

Land having a 1 in 100 or greater annual probability of river flooding; or Land having a 1 in 200 or greater annual probability of sea flooding.(Land shown in dark blue on the Flood Map).

Flood zone 3 development needs to submit a flood risk assessment as part of its planning application which determines if the site is classified as flood zone 3a or 3b as well as reviewing flood risk on the site and proposing suitable mitigation.

 

Flood Zone 3b

 

The Functional Floodplain

Flood Zone 3b is the functional floodplain: land where water from rivers or the sea has to flow or be stored during a flood. It will normally include land with a 3.3% or greater annual probability of flooding, roughly a 1 in 30 chance, with flood risk management infrastructure operating effectively, and land designed to flood.

The 3.3% figure is not a rigid definition. Local circumstances matter. The local planning authority should identify the functional floodplain and its boundaries in its Strategic Flood Risk Assessment, in agreement with the Environment Agency. Flood Zone 3b is not shown separately from Zone 3a on the Environment Agency’s Flood Map for Planning.

 

What can be built and where?

 

Essential infrastructure

 

• Essential transport infrastructure which has to cross the area at risk
• Essential utility infrastructure that must be in a flood risk area for operational reasons, including electricity generation and storage, electricity networks, telecommunications, water supply reservoirs and water treatment works that must remain operational during flooding
• Wind turbines
• Solar farms
• Hydrogen production facilities
• Carbon capture, distribution and storage facilities
• Heat networks
• Data centres
• Electric vehicle charging stations

Essential infrastructure is compatible with Zones 1 and 2 without the Exception Test. In Zones 3a and 3b the Exception Test is required. In Zone 3a it should be designed and constructed to remain operational and safe during a flood.

 

Highly vulnerable (including basement flats)

 

• Police and ambulance stations, fire stations and command centres
• Emergency dispersal points
• Basement dwellings
• Caravans, mobile homes and park homes intended for permanent residential use
• Installations requiring hazardous substances consent or falling under the Control of Major Accident Hazards Regulations 2015, subject to the NPPF’s essential-infrastructure qualification where a high-risk location is demonstrably necessary
• Installations requiring the relevant radioactive substances permit for landfill or dedicated near-surface disposal by burial

Highly vulnerable development is compatible with Zone 1. In Zone 2 the Exception Test is required. In Zones 3a and 3b the NPPF says the development should be refused.

 

More vulnerable (including houses and flats)

 

• Hospitals
• Residential institutions such as residential care homes, children’s homes, social services homes, prisons and hostels
• Buildings used for dwelling houses, including floating or rising designs, student halls of residence, drinking establishments, nightclubs and hotels
• Non–residential uses for health services, nurseries and educational establishments
• Landfill and sites used for waste management facilities for hazardous waste
• Sites used for holiday or short-let caravans and camping, subject to a specific warning and evacuation plan

More vulnerable development is compatible with Zones 1 and 2 without the Exception Test. In Zone 3a the Exception Test is required. In Zone 3b the NPPF says the development should be refused.

 

Less vulnerable

 

• Police, ambulance and fire stations which are not required to be operational during flooding
• Buildings used for shops; financial, professional and other services; restaurants, cafes and hot food takeaways; offices; general industry, storage and distribution; non-residential institutions not included in the ‘more vulnerable’ class; and assembly and leisure
• Land and buildings used for agriculture and forestry
• Waste treatment (except landfill and hazardous waste facilities)
• Minerals working and processing (except for sand and gravel working)
• Water treatment works which do not need to remain operational during times of flood
• Sewage treatment works, if adequate measures to control pollution and manage sewage during flooding events are in place
• Car parks
• Land-raising, unless it is part of or enables development with a higher vulnerability classification

Less vulnerable development is compatible with Zones 1, 2 and 3a without the Exception Test. In Zone 3b the NPPF says the development should be refused.

 

Water-compatible development

 

• Flood control infrastructure
• Water transmission infrastructure and pumping stations
• Sewage transmission infrastructure and pumping stations
• Sand and gravel working
• Docks, marinas and wharves
• Navigation facilities
• Ministry of Defence defence installations
• Ship building, repairing and dismantling, dockside fish processing and refrigeration and compatible activities requiring a waterside location
• Water-based recreation (excluding sleeping accommodation)
• Lifeguard and coastguard stations
• Amenity open space, nature conservation and biodiversity, outdoor sports and recreation and essential facilities such as changing rooms
• Essential ancillary sleeping or residential accommodation for staff required by uses in this category, subject to a specific warning and evacuation plan

Water-compatible development is compatible with Zones 1, 2, 3a and 3b without the Exception Test. In Zone 3b it should be designed and constructed to:

• remain operational and safe for users in times of flood;
• result in no net loss of floodplain storage;
• not impede water flows and not increase flood risk elsewhere

 

Conservation, Heritage & Protected Sites

What if a proposal fails the Sequential Test? A failure is a serious conflict with national flood-risk policy, but it is not an automatic statutory veto. The 2026 High Court decision in North Somerset District Council v Secretary of State confirms that matters such as lifetime safety and wider sustainability benefits can still be material considerations in the overall planning balance. Our Flood Risk Assessment guide explains the distinction carefully.

 

Flood Zones Page Updated: 27th August 2026