Thames Water's latest 48-hour sewage release amid a hosepipe ban has "nailed the myth" that dumping only occurs into rivers in high flow, said an environmental group.
Ash Smith, chair of Windrush Against Sewage Pollution (WASP), said: "Many rivers are still in very low and slow conditions and Thames Water is still applying for drought orders to take even more water from the aquifers, yet there is only one place that untreated sewage is going when the effects of 33 years of underinvestment mean that far too much rainwater still gets into the sewers and overwhelms inadequate sewage works - into our depleted rivers, and nationally our coastal waters as well."
During the first heavy rain for months, the water company started releasing sewage from its Witney treatment works on Sunday afternoon with the discharges continuing on Monday.
There was also an ongoing release from Oxford sewage treatment works from Sunday afternoon into Monday.
It is currently legal for water companies to discharge raw, untreated sewage into rivers in times of ‘exceptionally heavy rainfall’.
In October 2021, the Governnment came under fire for voting down an amendment to the Environment Bill that sought to stop the practice.
Most Conservative MPs, including Witney MP Robert Courts, voted against the amendment.
He said the main reason it was not accepted was because it came with no plan and no impact assessment of how it could be implemented.
Mr Courts said while he supported the principle “we are talking about transforming a system which has operated since the Victorian era" and said the preliminary cost could be anywhere between £150 billion and £650 billion.
Mr Smith said: "The government and even our own MP have been wrongly blaming the Victorians for this shambles but the reality is that Thames Water, while complaining about this, is still connecting surface water drainage from new developments to the foul sewer and charging new homeowners for it.
"They profit from the connection and then from dumping it in our rivers and they have been allowed to get away with it for far too long."
Dr Lidia Arciszewska, West Oxfordshire District Council's cabinet member for environment, said the council has no legal powers to stop Thames Water from making these discharges.
"However, we have a responsibility to our residents to do our utmost to incentify Thames Water to make improvements to their sewer networks and increase its capacity."
She said the council has regular meetings with the company and is holding a Waterways Day on November 18, bringing together Thames Water, Oxfordshire County Council, Windrush Against Sewage Pollution, CPRE and many other local stakeholders.
Among actions the council has taken so far are, with WASP, to query Thames Water's stated population data per sewage treatment works and hence its capacity calculation.
"As a result of this work, TW have now admitted publicly that they use two different sets of books to calculate population," she said.
It is also seeking the exact formula Thames Water uses to calculate works capacity so it can draw its own conclusions as to which are most under-capacity.
And it has asked for leak fixing activity in West Oxfordshire and upstream on the Evenlode and Windrush catchments.
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"Thames Water have confirmed that all STW sewage spill data will be available in real time online by year end. We intend to hold TW to this commitment," she said.
Robert Courts said the latest spills highlight the urgent need for the planned expansion of Witney Sewage Treatment Works.
He added: "The truth is that the only way to reduce sewage spills is to ensure water companies invest in infrastructure upgrades to end the routine use of storm overflows.
"This is precisely what the Environment Act and the subsequent Storm Overflows Reduction Plan sets out, requiring water companies to invest £56 billion in network upgrades over 25 years, the largest ever environmental infrastructure investment."
Thames Water said the latest sewage leaks were due to the heavy rainfall over the weekend leading to full storm tanks being discharged to the river, "as they are designed to do and in accordance with the site's permit".
A major project to increase the treatment capacity of the works will be completed by 2024, they said.
"We regard all discharges of untreated sewage as unacceptable and are working hard to accelerate work to stop them being necessary across our catchment area.”
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This story was written by Miranda Norris, she joined the team in 2021 and covers news across Oxfordshire as well as news from Witney.
Get in touch with her by emailing: Miranda.Norris@newsquest.co.uk. Or find her on Twitter: @Mirandajnorris
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