London flooding response

In July 2021, London was hit twice by extreme rainfall, which led to widespread flooding. At its heaviest, a month’s rain fell on some parts of the capital in just one hour.

The speed, severity, and scale of this rainfall tested our sewers and local authorities drains and gullies, beyond the limits they were designed to cope with, leading to the flooding of more than 2,000 properties.

There are different types of flooding and more information on who can help is available on our flooding webpage. 

We sympathise with everyone impacted by flooding but know that forecasts suggest severe rainfall events of this nature are set to become more common due to climate change.

To examine the causes of last July 2021 and actions we and partners could take to reduce the impact of such storms, two reviews were carried out.

Thames Water Review

We know the service we provided our customers with following the storms was not good enough, with many people unable to contact us and our teams slow to get to some of the worst hit areas.

We therefore carried out an internal review to examine the actions we took before, during and after the storms, to identify what we could have done better and develop these actions to ensure we do so.

London Flood Review

We wanted to understand why the flooding in July 2021 was so severe and whether our sewer network may have worsened the impact of the extreme weather.

To ensure a fully transparent and impartial process, we commissioned an independent assessment by a group of experts, chaired by Mike Woolgar.

The independent report had four core objectives:

• Research, understand and report on the “what, when, why and how” of the two July storms
• Examine the flooding mechanisms and consider the performance of drainage systems against design standards, with a specific focus on Counters Creek and Maida Vale Flood Alleviation Schemes
• Consider how changes to existing and planned drainage system works, operations or policies might have alleviated the flooding and make London more resilient to future storms
• Be as evidence-based as possible

The review has now completed and its reports can be found below:

Counters Creek performance commitment report

Ofwat asked us to report on the risk of flooding and level of resilience within the Counters Creek catchment. 

Read the full Ofwat requirements for this report. The requirements can be found in section 1.2.37 (pg 153) of the Ofwat PC commitments.

The report and its appendices are below.