Last reviewed 10 December 2021

On 19 November 2021, Aylesbury Crown Court sentenced Thames Water Utilities Ltd in a prosecution involving the discharge of raw sewage. Robert Spicer reports.

The Facts

On 24 and 25 July 2016, an estimated 500,000 litres of raw sewage was discharged into the Seacourt and Hinksey streams in Oxford. The discharge lasted 30 hours. It flowed for 3.5 kilometres along the streams, through a pub garden and past community allotments. The discharge was thought to be responsible for killing 3000 fish which included perch, chub, roach, gudgeon and bullheads.

Thames Water Utilities Ltd had failed to carry out essential maintenance to prevent blockages in a sewer which it knew was vulnerable to blockages. It had no system in place to identify blockages or pollution occurring and relied on reports by members of the public.

The discharge was reported to the Environment Agency by canoeists who found themselves paddling in sewage among dead fish. Officer of the Employment Agency traced the discharge to its source.

During a major sewer renewal project in 2012, the company chose a solution which saved them many millions and relied on a six-monthly cleaning of the sewer to prevent the known risk of blockages.

The company failed to comply with the environmental permit. It did not have a documented programme covering the maintenance of the sewer despite being in possession of a manual which set out the requirement for maintenance and the risk of blockage and pollution if it was not put into effect. The company had failed to adequately maintain this high-risk section of sewer for at least 16 years.

The Environment Agency had previously issued Thames Water with two formal warnings following earlier pollution from the same discharge point because of an earlier blockage in February and March 2012.

The company had failed to disclose highly relevant documents, which included a maintenance manual, until the 11th hour, only after members of the public had notified the Environment Agency of the existence of the manual.


Thames Water Utilities Ltd was fined £4 million plus £90,700 costs at Aylesbury Crown Court.

The Crown Court Judge is reported to have made the following comments.

  • This was yet another very serious breach of legislation in an area of outstanding natural beauty.

  • The waterfall of raw sewage was a disgraceful state of affairs.

  • The environment is not ours to treat as our own and we are living on borrowed time.

  • The failings in the case were frankly embarrassing and could not happen again.


A spokesperson for the Environment Agency is reported to have made the following comments.

  • It was quite horrific. Sewage pollution was bank to bank and there was a foul stench of raw sewage.

  • When officers from the agency traced the source, they found a waterfall of raw sewage discharging from a pipe into the streams. Among the dead fish, officers observed hundreds more on the surface, suffering and gasping for oxygen.

  • The fine sent out a clear warning to the boards of all water companies — invest heavily in maintaining sewers and don’t drop the ball when it comes to carrying out that maintenance.

  • Incidents like the pollution of the Seacourt and Hinksey steams were preventable and completely unacceptable, particularly at a time when the need to protect the water environment for wildlife and people has never been greater and when public consciousness related to environmental matters is so high.

The total amount of fines imposed on Thames Water Utilities Ltd since 2017 is £32.4 million for offences of water pollution in Oxfordshire, Berkshire and Buckinghamshire.

The Environment Agency and Ofwat have announced new investigations into sewage treatment works after water companies admitted that they could be releasing unpermitted sewage discharges.

The sustainability director of Thames Water commented as follows.

  • We are deeply sorry for this incident and the entirely unacceptable pollution that was caused to the Seacourt stream following a blockage of our sewer.

  • We pleaded guilty at the first opportunity and accept the judgment of the court that we failed badly by not inspecting and cleaning this part of the sewer system.

  • But things have changed. As part of the comprehensive turnaround programme launched by our new Chief Executive, we are doing five times as much sewer cleaning as we were in 2016.

  • The decision by Ofwat and the Environment Agency to look into sewage discharges across rivers and other watercourses has rightly brought this issue to the fore.

  • Our view is that it is unacceptable for untreated sewage to enter rivers, even when legally permitted, and we have an unprecedented amount of investment directed towards safeguarding our rivers and streams. This includes spending more than £1.25 billion at our sewage treatment works during our current five-year business plan.