5 years on, Londoners remember the impact of July 2021 floods

• Almost 320,000 homes and businesses in London are at high risk of surface water flooding, with at least 56,000 basement homes particularly vulnerable.
• Flood Ready London partners have committed £3.725 million to support practical action across the capital, including initial funding for 20 sustainable drainage schemes across Central London and the Lee Valley.
• Londoners are encouraged to check their flood risk and Met Office weather warnings, prepare a flood kit and take simple steps to help protect themselves, their homes and their communities.

In July 2021, thousands of Londoners saw floodwater enter their homes, businesses and communities with little warning. For many people, the flooding happened quickly, damaging homes and belongings, disrupting their lives and leaving difficult recoveries for those affected.

This July marks 5 years since that extreme rainfall caused devastating flash flooding across London. Londoners are being encouraged to check their flood risk and take simple steps to prepare, as Flood Ready London partners continue work to strengthen the capital's resilience against flash flooding, also known as surface water flooding.

The floods affected 24 boroughs and more than 2,000 properties, including homes, businesses, hospitals, schools and London Underground stations. The events showed how quickly heavy rainfall can affect London's communities, infrastructure, public services and transport networks.

Flash flooding can happen when intense rainfall falls faster than drainage systems can cope with and the ground can absorb it. It can affect areas far from rivers and can develop quickly, often with little warning.

The Environment Agency's latest National Flood Risk Assessment data predicts that almost 320,000 London homes and businesses are today at high risk of surface water flooding. At least 56,000 basement homes are particularly vulnerable because of their below-ground location. The London Climate Resilience Review identified surface water flooding as a very high risk for London, and warned that the capital is underprepared for the impacts of climate change.

The risk of flash flooding is real, and London must act together to reduce its impacts. Partners are investing in infrastructure and long-term resilience, but residents, businesses and communities also need clear information about how to prepare, respond and recover.

Community action is fundamental to becoming flood ready. Local groups, residents and businesses can help by looking out for neighbours, sharing trusted advice, reporting local flooding issues, and helping people understand what to do when heavy rain is forecast.

Flood Action Groups are one way communities can get involved, bringing local volunteers together to share knowledge, represent local concerns and work with flood risk organisations on practical ways to improve resilience. Practical local measures, such as water butts, rain gardens, de-paving where appropriate and using permeable surfaces can help slow the flow of rainwater and reduce pressure on drainage systems.

Simple actions can make a difference. Residents and businesses can:

• check Met Office weather warnings and forecasts for heavy rain or thunderstorms
• check their long-term flood risk
• prepare a flood kit
• know how to turn off gas, electricity and water supplies, if safe to do so
• move important documents, valuables and sentimental items to higher ground if possible
• check their household building or contents insurance covers flooding; if you don't have any, FloodRe may be able to help
• save key contacts, including insurers, landlords, housing associations and local councils
• avoid flood water and never drive or walk through it
• check drains outside your home and on your street are clear; report street drainage issues to your council, FixMyStreet or Love Clean Streets
• call 999 if there is a risk to life, serious illness or injury, or urgent help is needed to evacuate
• look out for neighbours who may need extra support, where it is safe to do so.

Since July 2021, organisations across London have worked together to strengthen the approach to flash flooding. Flood Ready London brings together the Environment Agency, London Councils, London Fire Brigade, the Mayor of London, Thames Water and Transport for London, and is supported by the Thames Regional Flood and Coastal Committee.

The partnership developed London's first Surface Water Strategy, published in 2025, which sets out a shared long-term approach to helping the capital better prepare for, respond to, and recover from flash flooding.

The partnership is now moving from strategy to delivery, with £3.725 million committed to support practical action. The first allocation of this funding will support 20 sustainable drainage schemes across the Central London and Lee Valley Surface Water Catchment Partnerships. These include projects at schools, housing estates, and high streets, using measures such as rain gardens, permeable paving and water butts to help slow, store and manage rainfall while contributing to greener, more climate-resilient neighbourhoods.

Elizabeth Rapoport, Chair of Flood Ready London, said:

5 years on from the July 2021 floods, London is remembering what happened and reflecting on the serious experiences shared by those affected. Flash flooding remains a real and growing risk for London. Water does not follow administrative boundaries, and no single organisation can tackle this challenge alone.

Flood Ready London is increasing London's resilience to flash flooding through collective action that benefits people, places and the environment. By working together, investing in practical solutions and helping people understand their own risk, we can reduce impacts and support a better prepared London.

Background

• London's highly urbanised landscape makes managing heavy rainfall particularly challenging.
• Roads, pavements, roofs, paved gardens and other hard surfaces can stop rainwater soaking naturally into the ground.
• During intense storms, large volumes of rainwater can quickly run off into streets, drains, sewers and low-lying areas.
• It can affect areas far from rivers and can develop quickly, often with little warning.
• As the climate changes, heavy downpours like those seen in July 2021 are expected to become more frequent and severe.

About Flood Ready London

• Reviews after the 2021 floods included a recommendation for the development of a London Surface Water Strategy.
• Key partners came together to establish the Flood Ready London partnership.
• Flood Ready London brings together the Environment Agency, London Councils, London Fire Brigade, the Mayor of London, Thames Water and Transport for London, supported by the Thames Regional Flood and Coastal Committee.
• The partnership developed London's first Surface Water Strategy, working with boroughs, communities, technical specialists and stakeholders.

About the London Surface Water Strategy

• The London Surface Water Strategy was published in May 2025.
• The Strategy sets out a shared approach to helping London better prepare for, respond to and recover from flash flooding.
• It recognises that resilience depends on sustained collaboration, investment, community involvement and action at every scale across the city.
• The Strategy recognises that increasing resilience will require more than engineering solutions alone.

About Surface Water Catchment Partnerships

• A surface water catchment is an area where rainwater drains and flows, above and below ground, regardless of borough boundaries.
• Because water does not follow political, administrative or community boundaries, managing flash flooding effectively requires partners to work at catchment scale.
• As part of delivering the London Surface Water Strategy, 10 Surface Water Catchment Partnerships are being established across Greater London.
• These partnerships will bring boroughs, infrastructure providers, communities and Flood Ready London partners together to better understand how water moves. Identify local priorities, develop projects and support long-term management of flash flooding risk.
• While each organisation has its own responsibilities, the scale and complexity of flash flooding mean closer collaboration is essential.

About current investment

• A total of £3.725 million has been committed to date by City Hall, Thames Water and the Thames Regional Flood and Coastal Committee partners to support delivery of the Strategy.
• From the first allocation, the Central London and Lee Valley Surface Water Catchment Partnerships will receive around £1.4 million between them.
• Funding will support practical and locally tailored solutions that help slow, store and manage rainfall more effectively.
• Alongside reducing flood risk, many of these projects can also help create greener, healthier and more climate-resilient neighbourhoods.