Before a Flood

Understanding flood risk

Sources of Flood Risk

Flooding can occur from a range of different sources including:


Properties located on the coast can be at risk from tidal flooding during storms and high tide conditions. The impacts of climate change and sea level rise means that tidal flooding is likely to affect more properties more severely in the future.


Fluvial flooding can occur along Main Rivers and Ordinary Watercourses.

Main Rivers are usually larger rivers and streams that have been designated and are the responsibility of the Environment Agency

Ordinary Watercourses include all other watercourses that have not been specified as Main Rivers and are the responsibility of Lead Local Flood Authorities.

Surface Water

Even if you are not located near a river or the sea, surface water flooding after periods of heavy and prolonged rainfall can create a flood risk, particularly in steeper catchments.


During long periods of heavy rainfall groundwater levels can rise towards the surface.

This can lead to water flooding up through the ground into or around a property.


Blockages or additional floodwater in the sewers can reduce the capacity of the network. This can lead to sewage backing up causing sewage flooding. Combined sewer networks are particularly at risk of being impacted by flooding.


Reservoir flooding is extremely rare in the UK due to very strict regulations and mandatory assessments. Reservoir failure can lead to significant flooding and will cause very fast flowing water to flow along the watercourses downstream of a reservoir in large quantities.

Am I at risk?

You can check if your property is at risk of flooding from rivers, the sea, surface water or reservoirs on the various agency websites below.

Climate Change
Am I at risk?

Historically, flooding and coastal change has had a significant impact on homes, businesses and communities across the UK. As a result of climate change, we are already seeing evidence of more frequent and more extreme flood events, with increasing numbers of home and businesses at risk of flooding.

Flood risk management: Who is responsible?

There isn’t a single organisation that is responsible for managing flood risk across the UK.

The organisations below are Risk Management Authorities (RMAs). They are responsible for different elements of flood risk management and must work together to effectively tackle flooding.

The Government

The Department for Environment, Food and Rural Affairs (Defra) leads on flood and coastal erosion risk management in England. Defra work with other government departments to develop and revise policies. These policies then delivered by Risk Management Authorities (RMAs).

The Flood and Water Management Act 2010 requires these Risk Management Authorities to:

  • Co-operate with each other.

  • Exchange information.

  • Work in a consistent manor.

Environment Agency

As detailed in the Flood Risk Management Act 2010, the Environment Agency has a strategic overview of all sources of flooding and coastal erosion.

 It is also responsible for:

  • Flood and coastal erosion risk management activities on Main Rivers and the coastline

  • Regulating reservoir safety

  • Working in partnership with the Met Office to provide flood forecasts and warnings.

Looking for opportunities to maintain and improve the environment for people and wildlife.

Lead Local Flood Authorities (LLFAs)

The Lead Local Flood Authorities, or LLFAs for short, are county councils and unitary authorities. LLFAs lead in managing local flood risks including risks of flooding from surface water, groundwater and Ordinary Watercourses.

District and Borough Councils

District and Borough Councils are key in local flood risk management.

They can carry out flood risk management works on minor watercourses.

They work in partnership with LLFAs and other Risk Management Authorities to ensure risks are managed effectively , including making decisions on development in their area.

Water and Sewage Companies

Water and sewerage companies manage the risk of flooding from water supply and sewerage facilities and flood risks from the failure of their infrastructure.

They maintain and manage their water supply and sewerage systems to manage the impact and reduce the risk of flooding and pollution to the environment.

 Where there is frequent and severe sewer flooding, sewerage undertakers are required to address this through their capital investment plans, which are approved and regulated by Ofwat.

Internal Drainage Boards (IDBS)

IDBs are independent public bodies responsible for managing water levels in low-lying areas.

They are the land drainage authority within their districts and their functions include supervising land drainage and flood defence works on ordinary watercourses.

More information about IDBs can be found here.

Highway Authorities

Highways authorities (the Highways Agency and unitary/county councils) have the lead responsibility for providing and managing highway drainage and roadside ditches under the Highways Act 1980.

Detailed information on flood risk management and who is responsible can be found here

Find your local

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For help and guidance on local flood risk management and to access support, please get in touch with your local council.
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