Environmental campaigners are calling for developments to be paused until sewage treatment works are upgraded to cope with them.
Windrush Against Sewage Pollution (WASP) has begun making submissions to significant planning applications in six sewage works catchments that are operating outside of their permits.
Pushed by WASP and councillors Lidia Arciszewska, Charlie Maynard and Alaric Smith, Thames Water has acknowledged that Bampton, Carterton, Woodstock, Chipping Norton and Witney along with Church Hanborough STWs all fall into this category.
WASP aims to ensure that Thames Water insists that West Oxfordshire District Council applies a 'Grampian condition' - a planning condition attached to a decision notice that prevents the start of a development - until the upgrade of the appropriate sewage works is complete.
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Thames Water already regularly asks WODC to impose this condition when it feels its sewer network is inadequate but it has never asked for one with respect to its sewage treatment works capacity.
Vaughan Lewis, of WASP, said they believe this is due to the cost implications for Thames Water.
He said: "Thames Water have been avoiding any reference to treatment capabilities where new development is concerned, focusing only on network capabilities, and in so doing have likely convinced planners that subject to suitable network upgrades all would be OK.
"Substantial investment is required to get these works to be compliant with their permits.
"Until upgrades are complete all these works remain non-compliant with their permits - that is, operating illegally.
"Any new housing will simply put more sewage into an illegally operating works, which will result in more dumping of untreated sewage into local rivers at a rate of 30 tonnes for every 100 new houses."
He added: "Let's be very clear that this is not WASP holding up housing. This is entirely due to Thames Water profiteering and the Environment Agency and Ofwat failing to do their job."
A team of WODC councillors has been having monthly meetings with Thames Water team since early autumn.
Dr Lidia Arciszewska, cabinet member for Environment and an Oxford University biochemist, said: "We keep asking questions about capacities of Thames Water sewage networks and treatment work stations in West Oxfordshire.
"We ask how Thames Water determine and update the population numbers they are using to estimate their infrastructure capacity needs. Every meeting brings some progress."
She added: "We have encouraged Thames Water to work with us at the planning level.
"In mid November Thames Water updated their statement for the housing development application for 150 homes at the North Field in Long Hanborough."
Thames Water requested a condition that no development should be occupied until confirmation was provided that either all sewage works upgrades required were completed or a phasing plan agreed to allow development to be occupied.
The water company provided a similar statement towards a planning application for development of 40 homes in Aston in the Bampton STW catchment area - although the development has been refused on other grounds.
Dr Arciszewska said: "Obviously, this strategy may lead to delays in the necessary rapid growth of housing developments in West Oxfordshire.
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"However, it is not sustainable to pump into our rivers additional 30 tonnes of raw sewage from each 100 new houses per day - this is roughly equivalent in volume to a standard size shipping container per day."
Richard Aylard, Sustainability Director at Thames Water, said: “We value our monthly meetings with the Council and the opportunity they provide for detailed discussions about water and wastewater issues in West Oxfordshire.
"This includes the expansion of our treatment works at Witney, which has already started, and at Bampton, Church Hanborough and Chipping Norton, all of which will follow soon, as well as potential work at other sites.
“In terms of planning applications, our specialist team look at each application individually as there may well be things we can do to improve the situation to the point where we do not need to raise an objection.
"Where the council have concerns we are always willing to review and discuss any advice we have given.”
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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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