Thames Water has reported a record 50% increase in raw sewage discharges into rivers in England for the year 2024, when compared to the previous year.

According to data compiled from event duration monitors at the water company’s facilities, the largest of the privatised water utilities in the UK was responsible for nearly 300,000 hours of raw sewage released into waterways, up from approximately 196,414 hours in 2023. This surge has raised concerns regarding the condition of Thames Water's sewage infrastructure, which has accumulated debts totaling £19 billion.

The data comes amid Thames Water's financial distress, as it has recently secured approval for a £3 billion emergency debt bailout from the court of appeal to avert collapse.

This bailout has faced opposition from environmental campaigners as well as a minority of the company's creditors, who argue that it is not in the public interest and advocate for temporary nationalisation as a potential solution.

The figures indicate that almost 90% of the recorded 298,081 hours of raw sewage discharges were linked to Thames Water’s sewage treatment works.

These facilities are currently the subject of a criminal investigation by the Environment Agency, which is probing allegations of illegal sewage dumping, alongside an inquiry from the water services regulator Ofwat that has instructed Thames Water to take urgent corrective actions.

Thames Water has acknowledged years of underinvestment in its sewage treatment infrastructure, characterising the situation as a consequence of 'sweating these assets.' The company has admitted that its failure to maintain its infrastructure has compromised public safety, water supply, and environmental integrity.

Specific incidents highlighted in the data report include:
- The Amersham balancing tanks in Buckinghamshire discharged raw sewage for a total of 4,842 hours in 2024, including a notable continuous discharge equivalent to 154 days into the River Misbourne.

- The Marlborough sewage treatment works was responsible for 2,786 hours of raw sewage discharges.

- The Chesham sewage treatment works recorded 2,681 hours of sewage discharges.

The UK government, represented by Environment Secretary Steve Reed, has established targets for water companies to minimize sewage spills, aiming for an average of 10 spills per sewage overflow by 2050. In contrast, the average recorded in 2024 was 45.2 spills per overflow, significantly above the target.

Studies indicate that many of the discharges have occurred in violation of permit regulations, with claims of illegal spills on dry days, particularly from the Marlborough sewage treatment facility into the River Kennet, which is a designated site of special scientific interest.

In response to the alarming data, Thames Water has emphasized the impact of weather conditions, citing 2024 as one of the wettest years on record that influenced the frequency and duration of storm discharge events.

The company pledged to invest heavily over the next five years into upgrading its aging infrastructure, presenting an ambitious plan described as a monumental undertaking given the complexity of its current system.

Thames Water also highlighted its commitment to transparency, noting it was the first UK water company to implement real-time data reporting of sewage discharges online.

Ongoing investigations by the Environment Agency and Ofwat continue to scrutinize the operations of Thames Water, with further developments anticipated as the inquiry unfolds.