Thames an ‘open sewer’ as half of treatment works ‘not fit for purpose’

Analysis shows more than half of sewage plants are unable to cope with rising volume of waste

THE Thames is becoming an “open sewer” because treatment plants are overwhelmed, with more than half unable to cope with demand from local homes and businesses, analysis shows.

Of the 90 sewage works in the upper Thames, 46 don’t have enough capacity to deal with demand, a report has found.

The Oxford Rivers Improvement Campaign (ORIC) analysed data supplied by Thames Water to work out how much sewage its treatment works could process and whether it was enough to handle demand. They said the data showed the company’s failure to invest in upgrading its systems over recent decades was the cause of sewage leaks that has left the river polluted. Thames Water is among water companies that have come under fire in recent months for dumping untreated sewage into rivers and the sea.

It came as a video released by the BBC appeared to show sewage coming out of a pipe at the Cassington works, one of those covered by the study.

ORIC data suggest Cassington has 74 per cent of the capacity it needs to process sewage correctly.

A spokesman for Thames Water said the plant had not released untreated sewage since March last year.

“Any problem seems to be occurring in the long pipe that takes the treated effluent to the river,” she said.

“We are determined to understand what is coming out of the final effluent pipe and we have taken further samples as part of our examination.”

Not one of Britain’s rivers passes chemical pollution standards, and this week Britain’s only designated river swimming spot, in Ilkley, West Yorkshire, was classified as “poor” after water quality tests showed it is heavily polluted with bacteria.

British sewage systems are designed to discharge untreated sewage into rivers and the sea when the volume becomes too great for them to process.

This is only supposed to happen at times of exceptionally heavy rainfall, but the analysis suggests that some of the treatment plants are also unable to cope with normal or dry weather.

The group’s analysis, seen by The Telegraph, showed that Oxford’s sewage treatment works had 61 per cent of the capacity it needs, while Swindon’s had 86 per cent and Banbury’s had just 43 per cent.

Mark Hull, a former water industry consultant and co-author of the report, said: “Our modelling shows that half the sewage works in the upper Thames do not have enough capacity; they are not fit for purpose. Our rivers have returned to being open sewers.

“We believe this is typical of the whole river Thames, and indeed many, if not most, rivers in England.”