Rise in sewage pollution from Thames Water’s ageing treatment works | Thames Water

Sewage pollution from ageing Thames Water treatment works that have not been upgraded increased last year, causing the company to again fail to meet its legal targets, according to its financial report.

Across the Thames Water area, the number of incidents of pollution from treatment works and the pipe network increased to 350, compared with 331 in 2022. The rise was attributed to delays in investment to create more capacity at many of the company’s 400 ageing sewage treatment works. Chris Weston, Thames Water’s chief executive, said the works could not cope with a 40% increase in rainfall and exceptionally high levels of groundwater.

Asked why Thames had failed for many years to invest in upgrading treatment works, Weston repeated that the works were “old”. He said: “They require a lot of development, a lot of investment into things like putting in storm tanks. All of that takes time and requires a lot of investment on top of what we have done already.”

The company said there had been a “significant increase in sewage treatment works pollutions” in the year, caused by delays to pollution improvement engineering programmes, as well as the installation of more monitoring at works.

The need for improvements at the huge treatment works at Mogden in south-west London, and delayed works to increase capacity at treatment works in Witney in Oxfordshire, Chesham in Buckinghamshire, and Fairford in Gloucestershire were given as reasons for the rise in pollution incidents.

Campaigners in these areas have raised concerns for many years about pollution into rivers from the treatment works. In March, sewage was pumped into the River Chess from the Chesham treatment works for more than 800 hours over more than a month. Thames Water admitted the works had “a history of prolonged storm discharges”.

Weston said: “Pollutions are a massive area of focus for Thames. We deal with over 5bn litres of sewage of waste every day. All of that has to be treated through sewage treatment works. People in Thames Water go to extraordinary lengths to make sure that the network is functioning as it should and do all they can to avoid pollution.

“Rain has a huge impact on spills. Our sewage treatment works can only take a certain capacity and we have to protect them. When we get adverse rainfall as we did in February, it is a volume that our treatment works were never designed to cope with.”

Thames Water is at the centre of an Ofwat investigation into widespread illegal sewage dumping across its treatment works and faces huge fines. The Environment Agency is conducting a criminal investigation into illegal sewage dumping from its network.

In its business plan to 2030, which has been submitted to Ofwat, the company is seeking to be treated differently from all other water companies and face lower fines for polluting rivers, as it attempts to stay afloat.

Thames, which has debts of almost £15bn, wants to be allowed to raise bills by 59% to pay for investment in infrastructure, as well as paying out higher dividends to its shareholders.

The company has admitted it has been sweating assets for many years and said bills needed to rise to pay for the investment.

Ofwat is due to make a draft determination on the business plan on Thursday.

Weston said one of the reasons the company was putting forward a plan with significant investment was to tackle its ageing treatment works.

Paul de Zylva, a senior sustainability analyst at Friends of the Earth, said: “Water companies have had free licence to line their shareholders’ pockets handsomely for decades while letting our rivers and seas fill with sewage and infrastructure crumble.

“It’s staggering that the company is still counting on weak regulation to allow it to survive by pushing its problems on to its customers – asking Ofwat to allow it to increase bills by a shocking 59%. This means bill payers being left to subsidise what little it’s prepared to invest towards fixing the pollution and sewage scandal. The regulator must end this licence for water companies to profit from pollution, while wildlife and our health is put at risk.”

James Wallace, CEO of campaign group River Action, said: “There is nothing to cheer as this failing water company, the largest in Europe, continues to desperately prioritise the interests of investors and lenders before the health of rivers and river users. A good first start would be for the government to properly resource the environmental regulators such as the Environment Agency in England to ensure they can police and prosecute polluters.”