Five years on: Remembering the July 2021 Floods 

A commuter walking through flooding in London. 

In July 2021, thousands of Londoners watched floodwater enter their homes, businesses and communities with little warning, turning an ordinary summer day into an unforgettable one. 

Over two separate days, extreme rainfall overwhelmed parts of the capital, causing widespread flash flooding across 24 boroughs. Homes, businesses, schools, hospitals and transport networks were affected. More than 2,000 properties flooded, with 1,755 calls made to the London Fire Brigade over four hours.  

Five years on, we’d like to reflect on what happened and consider what London has learnt since. 

Surface water flooding remains a significant risk 

The July 2021 floods were caused by surface water flooding, often referred to as flash flooding. 

This happens when intense rain falls faster than the ground and drainage systems can absorb it. Unlike river flooding, it can occur almost anywhere and is not limited to areas near rivers or the coast. 

One of the July 2021 storms produced around five times more water than parts of London's sewer network could accommodate.  

Surface water flooding remains one of London's most significant climate risks. 

Around 320,000 properties across the capital are currently at high risk of surface water flooding, including approximately 56,000 basement homes. As climate change increases the frequency and intensity of heavy rainfall events, the likelihood of similar flooding events is expected to grow. 

London's urban environment can make managing rainfall particularly challenging. Roads, pavements and buildings leave less space for water to soak naturally into the ground, increasing pressure on drainage systems during storms. 

A London taxi, bus and cyclist travelling through flood water on Tower Bridge.  Flood risk does not stop at borough boundaries 

One of the clearest lessons from July 2021 was that flood risk is a shared challenge. 

Rain falling in one borough can affect neighbouring communities, transport networks and infrastructure. Surface water flooding does not follow political boundaries and can affect multiple areas simultaneously. 

No single organisation is responsible for all aspects of flood risk management. 

Therefore, building London's resilience depends on key organisations and communities working together towards a common goal. 

How London has responded 

The July 2021 floods and reviews that followed prompted a more coordinated approach to managing flood risk. Flood Ready London was established to bring together the organisations responsible for different aspects of flood risk management: the Environment Agency, London Councils, London Fire Brigade, the Mayor of London, Thames Water and Transport for London. 

Together, the partnership is increasing London’s resilience to flash flooding through collective action that benefits people, places and the environment. 

A major milestone was reached in 2025 with the publication of London's first Surface Water Strategy. The Strategy provides a shared long-term framework for improving resilience across the capital and sets out how partners can better understand risk, coordinate investment and deliver change. 

Flood Ready London logo.   From strategy to delivery 

The focus is now firmly on turning plans into action. 

Flood Ready London partners have committed £3.725 million to improving resilience across the capital. Ten Surface Water Catchment Partnerships are being established across Greater London to bring together local authorities, infrastructure providers, communities and flood risk management organisations. 

These partnerships are based on natural catchments – the areas where rainfall collects and flows. This reflects a simple reality:  

Water follows geography, not administrative boundaries. 

Central London and the Lee Valley are the first catchments to receive investment. Funding will support 20 sustainable drainage projects, with further investment and schemes to follow.

These projects include measures such as rain gardens, permeable paving, green roofs and other nature-based solutions that help slow, store and manage rainfall before it enters drainage networks. Alongside reducing flood risk, they can improve public spaces, support biodiversity and enhance water quality. 

Many boroughs are already delivering this type of work, with Flood Ready London helping to connect and support activity. 

A Sustainable Drainage System (SuDS) feature on a residential road.  Everyone has a role to play 

Alongside organisations improving resilience, it’s important for us all to understand our own risk. 

Being flood ready is not only about major infrastructure or city-wide planning. Local knowledge and community action are also essential. Residents, businesses, community groups and local volunteers can help by sharing trusted advice, looking out for neighbours, 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. They bring people together to share local knowledge, represent community concerns and work with flood risk organisations on practical ways to improve resilience.

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 your 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 Looking ahead  Pedestrians walking along a main road, next to a SuDS feature. 

Five years on from the July 2021 floods, London is remembering what happened, reflecting on the lessons learned and recognising the progress that has been made. 

There is still more to do. As climate change continues to affect the city, improving resilience will require sustained investment and collaboration.

By working together across boroughs, organisations and communities, we can help protect the people, places and services that make London thrive. 

https://environmentagency.blog.gov.uk/2026/07/15/five-years-on-remembering-the-july-2021-floods/

seen at 12:04, 15 July in Environment Agency: For homes and habitats..