
The UK’s largest water company has invested £20 million over the last three years to make its sewers smart by installing over 20,000 monitors that provide real-time data on the health of the network. These devices alert its teams to blockages that could turn into pollutions and flooding.
Thames Water is improving how it manages the wastewater network, enabling its teams of engineers, analysts, and data experts to identify problems earlier and take faster action. This means blockages can be tackled before they cause issues for customers or the environment.
Key Findings
Engineer installing a monitor.
Thames Water has invested £20 million to make its sewers smart and prevent flooding and pollutions.
20,000 monitors across the Thames Water region have helped identify and remove 11,500. blockages between March 2021 – March 2024.
This investment is part of Thames Waters commitment to using data and technology to drive actionable insights and improved its service to customers.
As part of a pilot scheme along Wealdstone Brook in London in 2023, the water company installed over 1000 monitors to gain greater insights into the patterns of blockages around the critical water course. This insight has led to over 100 blockages being cleared so far along the brook and the success of the scheme has paved the way for future installation strategies.

Between March 2021- 2024 Thames Water monitoring network has located and removed over 11,500 blockages across the entire region identified by these monitors. In its Mogden catchment, which covers the north west, west and majority of south west London, the company have 4964 monitors contributing to the smart sewer system. Since January 2023, these have helped identify and remove 2240 blockages across the west side of London.
Thames Water is expected to install a further 31,000 monitors by 2030, to continue making its sewers smarter. By using the data retrieved from the monitors, Thames Water is also able to decipher which areas of its network needs urgent upgrades and where improvements will be required in the future.
Anna Boyles, Head of Environmental Performance at Thames Water, said:
"At Thames Water, we are always looking at how we can use data and digital technology to improve the way we work and reduce the impact on our customers and the environment. Our smart sewer network is a major step forward in preventing blockages before they happen, and we are committed to expanding this work over the coming years."
"With 20,000 monitors already installed, we are excited to build on this progress. Our ambitious five-year business plan will help us deliver key improvements for our customers, including the installation of 31,000 additional monitors by 2030.”
Thames Water cleared around 52,000 blockages caused by sewer abuse in 2024. These are caused by items such as wet wipes, sanitary items and cotton pads that can't break down. This can force raw sewage to back up drains, manholes and spill into watercourses. The water company continues to encourage members of the public to only flush the three p’s: pee, poo and toilet paper.