The independent London Flood Review commissioned by Thames Water examining the severe flooding that affected many parts of London in July 2021 has now concluded and has been published.

The release of the investigation’s final report marks the fourth and final publication from the London Flood Review (LFR). It summarises the review findings and puts forward recommendations so that lessons can be learned and future impacts are mitigated. The LFR sought to:

• better understand the extent and causes of the 2021 floods
• assess how the drainage systems performed
• recommend how the increasing risks of future flooding events can be managed

Outcome and main findings

The speed and severity of rainfall which fell during the two storms was the main cause of the flooding, with both rainfall events exceeding the current design capacity of the below ground systems. For example, despite there being available capacity in the sewer systems, flows of water were often held up by the gullies which did not have the capacity to deal with such extreme flow rates.

The LFR acknowledges that weather events like those that occurred in July 2021 are likely to occur more frequently in the future. Consequently, as flooding is not any one organisation’s responsibility, the Review notes that the many parties which manage flood risk in the capital must work together to identify solutions to manage multiple sources of flooding and identify potential funding to ensure that the impacts of flooding are managed effectively. The LFR’s recommendations, grouped around five core themes of governance, funding, evidence, communications and strategic planning.

Sarah Bentley, Chief Executive Officer, Thames Water said: “As severe weather events look to become increasingly common, these recommendations will play an integral part in ensuring Thames Water continues to improve its service, deliver for its customers, protect the environment and give back to the communities we serve.

“While there is much as an organisation we can learn from this review, the clear takeaway is the necessity of collaboration. Ensuring that our network can operate effectively, while minimising the risk of impact of future flooding, must be the shared focus of all organisations with responsibility for London’s water network and drainage systems. We look forward to working closely with our partners in surface water management to build greater resilience for people living and working in London and the Thames Valley.”

The full story in Water Briefing can be found here. Further information can be found on the London Flood Review website here.