In 2023, Thames Water discharged 14.2 billion litres of sewage into the River Thames in central London. This alarming figure, revealed through freedom of information

requests, underscores the significant volume of effluent released by the UK’s largest water company.

One particularly severe incident occurred at the Crossness sewage works in Bexley, south-east London, where 430 million litres of effluent were released in a single day in November.

These disclosures come amid increasing public and political focus on sewage pollution. Recently, England's chief medical officer, Sir Chris Whitty, identified sewage pollution in UK waters as a “public health priority” that requires serious attention. The issue is also gaining traction in political debates, particularly in marginal constituencies in southern England ahead of the upcoming election on July 4.

Thames Water, serving the largest number of customers in the UK, points to the £4.5 billion Tideway Tunnel project, slated to open next year, as a major step towards reducing sewage leaks. This project is expected to significantly cut the amount of sewage entering the Thames.

The company employs electronic devices to monitor the quantity of effluent discharged into the river, particularly in areas covered by the Tideway Tunnel. Between 2020 and 2023, these devices recorded at least 85.9 billion litres of sewage being pumped into the Thames, with 14.2 billion litres reported last year alone.

Thames Water has announced plans to upgrade 250 sewage treatment works and sewers, including a £100 million upgrade of the Mogden facility in south-west London, where the worst incident of 2023 saw 558 million litres of sewage discharged in October.

Sarah Olney, the Treasury spokesperson for the Liberal Democrats, described the sewage outflows as “disgusting” and called for the installation of monitors on all combined sewage overflow pipes to measure both volume and frequency.

Public and political scrutiny of water companies' finances is also intensifying. Research by the Financial Times indicates that the 16 water and sewage companies in England and Wales paid out £78 billion in dividends and accrued £62 billion in net debt between 1991 and March 2023.

Ofwat, the sector regulator, was expected to rule in June on potential bill increases for water companies in England and Wales through 2030, but this decision has been postponed until July 11 due to the election. This ruling is crucial for Thames Water, which is grappling with £18 billion in debt and needs a £750 million cash injection from shareholders this year to continue operations and fund infrastructure improvements.

In response to the situation, the Liberal Democrats are advocating for special administration measures, while the Labour Party calls for a regulatory overhaul.

Thames Water stated that retrofitting the entire network with volume monitors would be prohibitively expensive. However, they emphasized their commitment to improving river health, noting that the Tideway Tunnel is expected to capture 95 percent of untreated sewage entering the tidal section of the Thames in a typical year once it becomes operational. Photo by Jim Linwood, Wikimedia commons.