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Date updated: 17/03/2023

If you experience flooding in the City of London please report it to us at Flood Risk

The City of London Corporation is working to ensure that the Square Mile stays at low risk from flooding. On this page you can find out about the risk of flooding in the City, guidance on flooding, and what the City are doing to protect the Square Mile including our Local Flood Risk Management plan and our Strategic Flood Risk Assessment.

What are the risks of flooding?

There are relatively small areas of the City that are at risk of flooding. It's vital to know about the risk to your property to be able understand how to prepare for it.

The City of London Strategic Flood Risk Assessment (2017) provides the most up-to-date information on the risks of flooding in the Square Mile. This includes tidal, surface water, sewer and groundwater flooding. Maps showing the extent of each of these can be found in the appendices.

Surface water flooding is one of the City's higher risk and as Lead Local Flood Authority the City Corporation is responsible for managing it. The is a 'residual risk' of flooding from a breach in the Thames' defences. The river defences are monitored twice a year and the owner has a duty to maintain them.

Flood Guidelines

Whether your a business, building owner or resident you can take steps to reduce the impact of flooding on you even when it may occur outside of the Square Mile. The City Corporation has created guidance on how City businesses and building owners can prepare for flooding. This guidance is in the flooding document library.

Use a combination of the sites below to provide weather warnings and flood alerts. These services can provide enough time for temporary flood protection measures to be put in place. In the event of a possible flooding incident, the Environment Agency and the Met Office provide a suite of services to communicate forecasts and broadcast up-to-date information to the public. These include the following:

Floodline Warning Direct

Floodline Warning Direct is a free 24 hour flood warning service, provided by the Environment Agency, where individuals can register their properties. You are encouraged to sign up for this service. You can opt to receive a warning by telephone, text or email.

Environment Agency

Met Office information

The National severe weather warnings page provides detailed information and navigates the user to other useful information provides detailed information. The Weather Observation Website (WOW) is a hub for UK weather observations. This service allows anyone to submit their own weather data, anywhere in the world. These observations are a source of real-time information.

Your local media

When the situation becomes a cause of concern for ground, property and life, flood alerts and warnings will be broadcasted on local media (television, radio and the internet).

Business continuity is the capability of your organisation to continue to deliver its products or services following a disruptive incident. Robust business continuity arrangements are essential for businesses of any size - devising strategies to protect your key products, services and critical activities will enable you to trade through a disruption and recover promptly afterwards. You can obtain advice on developing and exercising your business continuity arrangements by contacting the Contingency Planning Team. There is no charge if you are based in the City of London.

All new developments in the City of London should consider the need for a flood emergency plan. This is considered as part of the planning process. The City Corporation is developing guidance on when an agreed Flood Emergency Plan is required, the current draft is available in the flooding document library.

Flooding document library

What is the City Corporation doing to protect the Square Mile from flooding?

The City Corporation, as Lead Local Flood Authority coordinates the actions to address flood risk in the City, including:

  • the preparation of a local flood risk management strategy
  • the investigation and reporting on flooding incidents
  • the maintenance of a register of flood prevention assets
  • and acting as "approving body" with regard to surface water drainage

Documents prepared by the City Corporation to report on the flood risk in the City are as follows:

The City of London Local Flood Risk Management Strategy 2021-2027 (LFRMS) details the flood risks that the City faces, including flooding from the tidal River Thames, surface water and sewer surcharges and rising groundwater. As a Lead Local Flood Authority, the City Corporation has the responsibility to develop, maintain, apply and monitor strategy for local flood risk management in the area. The LFRMS includes a series of objectives and measures the City Corporation and other partners need to take to reduce their risks from flooding. The LFRMS is available in the Flooding document library. 

Reports on a Strategic Environmental Assessment and an Equality Impact Assessment, and a public consultation have informed the LFRMS. The reports are also available in the Flooding document library.

The Multi Agency Flood Plan covers the background and procedures for a multi-agency response to a flood incident in the City of London.​ The plan is written in collaboration with the other agencies who would respond and is regularly reviewed and updated.

The City Corporation's Flood Risk Asset Register is a list of structures that we consider are likely to have a significant effect on flood risk. The register provides a resource to assist in flood resilience planning and aid investigation following a flooding incident. There is a Flood Risk Asset Register map.

The City Corporation has produced briefing notes for individual properties in the flood risk area, see the Flood Risk Map to access them. These documents outline the flood risk to a particular property and the planning policy that relates to flood risk in the area.

The City Corporation undertakes investigations into flooding incidence where this is reported to us. In line with our statutory duties under Section 19 of the Flood and Water Management Act 2010 where this impacts multiple properties we prepare and publish a Section 19 flood investigation report. These reports are available from the flooding document library. 

If you experience flooding in the City of London please report it to us at Flood Risk.

The City Corporation has now adopted the first Riverside Strategy on the tidal Thames. The Square Mile like the much of central London is at increased risk from sea level rise. The Thames Estuary 2100 Plan sets out an estuary wide approach for providing flood protection for the coming century. The Riverside Strategy establishes how the City Corporation could play a role in securing the protection along our stretch of the Thames as part of the transformation of the local river flood defense.

The adopted version is now available in the Flooding document library, as is an introductory StoryMap

The City of London Strategic Flood Risk Assessment (2017) provides the most up-to-date information regarding the risks the City faces from tidal, surface water, sewer and groundwater flooding. In the SFRA maps list you will find maps which show the flood risk in the City.

Strategic Flood Risk Assessment PDF (1MB)
Date submitted: 20/01/20
Strategic Flood Risk Assessment document library