Thames Water has been handed a £2M fine by the Environment Agency after allowing raw sewage to flow into a river in 2015.
The toxic waste killed around 150 bullhead fish after flowing into a tributary of the River Thames for at least 24 hours.
Judge Peter Ross, at Oxford Crown Court on 21 December, ruled the incident was a high-end, category three harm offence.
He branded the incident a “reckless failure” on Thames Water’s part to take sufficient action to prevent a spill and ordered the company for pay full costs of £79,991.57.
Thames Water had, at an earlier hearing, pleaded guilty to two charges of breaching environmental law.
The incident saw a backlog of raw sewage forced into the water from a sewer pipe that was unable to hold it. Sewage also escaped from a manhole and onto a residential front garden.
Furthermore, Thames Water was aware that a pumping station had failed several times in the 12 months up to and including the incident in August 2015.
Robert Davis, who led the investigation for the Environment Agency, said: This incident was foreseeable and avoidable. Thames Water didn’t recognise the increased risk to the environment, ignoring or failing to respond adequately to more than 1,000 alarms.
He added: “We hope this prosecution sends a loud and clear message that the Environment Agency will not accept poor operation, management and maintenance of sewage pumping stations.”
However, Thames Water external affairs and sustainability director Richard Aylard said: “We take our role in protecting the environment extremely seriously and are really sorry for what happened here in 2015.
“We have made a series of improvements since this regrettable incident, including bringing in more people, more maintenance, more training and better systems.
“In the three-and-a half-years since, we have not had a serious incident at any of our 4,700 pumping stations.”
At the start of September last year, Thames Water pledged to invest £11.7bn in upgrades, including £2.1bn to “boost resilience and reduce leakage”.
Part of that pledge was a £203M contract of work to detect faults within its pipes.
Thames Water made the pledge after water watchdog Ofwat said that water companies had to “up their game” in cutting leaks.
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