According to a campaign group, investment in expanding Thames Water’s sewage treatment plants is far below what is required to prevent raw sewage from entering rivers.
Campaigners analyzed 106 treatment facilities in the upper Thames region, which extends from the Chilterns to the Cotswolds. A treatment work is where wastewater is treated and stored before it is released into the environment. According to the research, three quarters of the treatment works were not able to handle the volume of wastewater generated by the population. The possibility of raw sewage being released into the environment increases if a treatment plant is exceeding its capacity.
According to the Oxford Rivers Improvement Campaign, (ORIC), only 15 of the 83 works needed to be increased in capacity by Thames Water in 2020-2025 were included in investment plans. Ampney St. Peter has been closed for expansion.
The author of the analysis report, Mark Hull, said that this is shocking stewardship. He stated that assets were privatized a third of century ago in the belief that only the private sector would be able to invest the required amount for a cleaner and healthier water business.
Thames Water however stated that the calculations for the required works size were too simplified and misleading.
Hull stated that the group had examined details of the Thames Water investment in the plants from 2025 to 2030 and concluded that they were still not able to handle the required treatment by 2030.
He wrote that “there is clear evidence that these expansions were seriously inadequate” and only two of the 12 cases in which the amount of hydraulic capacity was known will have sufficient capacity by 2025. All 12 will also have insufficient capacity by the 2030s. “Even though they invest it is not enough.”
The campaign group calls for an urgent emergency investment program to increase wastewater treatment capacity. Thames Water should also be fined until it improves its performance. Planning approvals for major developments must be contingent upon adequate water treatment work capacity.
According to campaigners, an average analysis of the discharges from treatment plants into the River Thames, and its tributaries around Oxford shows that a typical treatment facility discharges diluted rawsewage for eight hours per week. A larger work may discharge sewage for 11 hours.
Concerns about the scale of Thames Water’s investment in treatment works were raised after Ofwat, the regulator, criticized water companies for not investing enough in treatment plants in order to prevent overuse of raw wastewater discharges.
Ofwat has set allowances for companies to invest in maintaining and improving their water networks. Between 2020-2022, 14 companies spent less on their water network improvement than they did on their wastewater network improvement. Eight companies also underspent on their wastewater network improvement budgets.
The report examines, for example, the Oxford sewage treatment plant. It has been releasing untreated sewage into Thames for 17 to 35 hours per week. According to campaigners, the works are currently able to handle 62% of the population’s needs.
Hull stated that the area has a high level of housing construction, and the need for additional capacity to meet the demand is a major concern. The plan is to increase the capacity by 24%
Hull stated that “our work underscores our longstanding call to a programme for emergency investment to address what is a more serious crisis – and one that Thames Water simply is not managing.”
The Thames’s only official bathing area has failed to pass tests for bacteria caused by sewage pollution.
Thames Water published near-real-time information on raw sewage releases last week in an interactive map. According to the company, “We are on track to deliver an investment program of PS1.25bn. This is aimed at maintaining our operational sites between 2025 and 2020 – an average PS250m per year. Our shareholders approved additional PS2bn in expenditures to improve performance and deliver better outcomes for customers, river health and leakage. This investment step is critical in the acceleration of our CEO’s eight year turnaround plan.
According to the company, campaigners used a single-size-fits all approach to their analysis. “In practice, we use a catchment-specific process that was agreed upon with the Environment Agency to determine how much each work needs to have. Based on actual measurements of the speed that the sewers drain to treatment works, this calculation is made. The permit issued by Environment Agency includes the agreed capacity. Fairford, Witney and Bampton are among the sewage treatment plants in the upper Thames that have increased capacities. They also include Church Hanborough, Bourton On The Water, Milton Under Wychwood, Church Hanborough, Bourton On the Water, Chipping Norton, Church Hanborough and Bourton on The Water. There is also an increase in storm tank capacity at other works.
The company stated that Ampney Saint Peter’s expansion was cancelled. “We recognize storm spillages at Ampney Street Peter sewage treatment works needs to be reduced. We are currently in the design process to achieve this goal, with delivery slated for 2026.”