Untreated sewage has been dumped around Didcot for the equivalent of just under 37 days since the start of the year leaving streams "sometimes literally full of sewage", say campaigners.

Data provided by Thames Water itself shows sewage has been discharged from Didcot sewage treatment works for 883 hours in 2024, said Windrush Against Sewage Pollution (WASP).

Didcot discharges untreated sewage into the Moor ditch, which runs through the Southmead industrial estate north of the A4130. It flows into the Thames near Long Wittenham.

In common with most waters downstream of sewer outfalls, there are no warning signs about the risks even though people walk along it, dogs can play in it and drink from the streams "sometimes literally full of sewage", said WASP chair and founder Ash Smith.

Herald Series: WASP chair Ash Smith

He said: "To go on the sewage works sites, we have to wear protective clothing including gloves and eye protection but when the sewage leaves the site, anyone can swim and play in it in terrible ignorance of the risks, as they often do.

"Bacteria levels can be sky high and we have heard many stories of dogs that have been sick and even died after contact with sewage, but no one has had an autopsy and toxicology done, so blame cannot be established."

The EA's monthly water situation report for the Thames area shows this February was the wettest on record, with a total of 134mm of rain, 281 per cent of the long term average.

Water companies claim that untreated sewage is released to stop it backing up into people’s homes, but WASP founder Ash Smith disagreed

He said: "The reality is that water companies have exploited poorly applied legislation to dump untreated sewage and get away without prosecution most of the time simply to prop up underinvestment and the shortfall in capacity that resulted from it.

"Illegal activity has become profitable," said Mr Smith.

Herald Series: The huge amount of wet wipes at Didcot Sewage Treatment Works open day in 2018

Didcot, which also covers Milton, Harwell, the Hagbournes and Blewbury, was one of the sewage works in the prosecution of Thames Water in 2017 when the company received a £20million fine, which was a record-breaking penalty at the time.

Mr Smith said: "It represented about 2.4 per cent of the money paid to shareholders and chief executives during the four years that the company was polluting in that way.

"Very much like processing the transaction through PayPal or a credit card – just a business expense."

He added: "With a general election coming and sewage pollution now on the list of voting issues we are looking for proposals that will take the profit out of pollution."

A Thames Water spokesperson said: “From time to time, when the treatment capacity of the works at Didcot is exceeded, there may be discharges of untreated sewage, once the storm tanks at the works are full.  

Herald Series: Didcot sewage treatment works in 2003, left, and 2021

"We regard any untreated discharges as unacceptable and are doing our best to make them unnecessary, with the assistance of our regulators.  

"Any such discharges are reported on the live map on our website, so that everyone can see what is happening. 

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"We remain committed to reducing the need for untreated sewage discharges and to stop them occurring.

"We have published plans to upgrade over 250 of our sewage treatment works and sewers, including Didcot sewage treatment works.

"This work will increase sewage treatment capacity at the site, reducing the need for untreated discharges in wet weather. ” 

Thames Water said it plans to upgrade Didcot sewage treatment works to improve its ability to treat the volumes of incoming sewage. 

The scheme is due to be completed in 2028.