Thames Water Under Scrutiny as Hogsmill Sewage Works Breaches Environmental Permit, Threatening Newly Designated Bathing Spot
Kingston, UK – [Insert Date] – Thames Water’s Hogsmill Sewage Treatment Works (STW) has been found in "breach of its environmental permit" on four critical counts by the Environment Agency (EA), according to a newly released inspection report. This alarming discovery comes just weeks after a stretch of the River Thames at Ham and Kingston was proudly designated as London’s first official bathing site, raising serious concerns about public health and environmental integrity.
The EA’s Compliance Assessment Report, dated May 11, 2026, details significant non-compliances at the Hogsmill STW, which is responsible for treating wastewater from Kingston, Surbiton, and surrounding areas. These breaches include:
- Significant Impact from Storm Storage Shortfall: The report highlights a critical deficiency in the site’s storm tanks, which hold substantially less than the required 31,182m³ of offline storage. The EA warns that this shortfall is "expected to significantly increase frequency and duration of storm discharges from the site," directly leading to untreated sewage entering the Thames in Kingston.
- Overdue Improvement Works: A crucial scheme designed to expand storm tank capacity, originally slated for completion in March 2025, has been significantly delayed. Thames Water has now informed the EA that it anticipates finishing the project in 2028, a full three years behind schedule.
- Failed Flow Monitoring (Minor Impact): Equipment vital for measuring flow passed to treatment failed its MCERTS certification. Inspectors found that return liquors were being "double-counted," undermining the reliability of data and raising doubts about whether storm discharges are occurring only when permissible.
- Uncontrolled Discharge During Storms: The EA discovered that unprocessed "site returns" are being discharged into the environment via the site’s permitted storm outlet during storm events. This constitutes a separate breach, as the site is only licensed to discharge settled storm sewage at this point. The Agency’s spill-monitoring data reveals a troubling pattern, with storm discharges recorded every year since at least 2021, including 33 spills totaling 186.75 hours in 2023 alone.
The Hogsmill STW is situated approximately 5 kilometers upstream of the newly designated bathing water site on the River Thames at Ham and Kingston, which received its official status on May 15, 2026 – just four days after the EA’s inspection. This proximity amplifies concerns regarding the potential impact of the sewage works’ non-compliance on recreational users and the ecological health of the river.
In response to these findings, Save Our Lands and River (SOLAR), a prominent campaign group actively challenging Thames Water’s proposed Teddington Direct River Abstraction (TDRA) scheme, is intensifying its call for public action. SOLAR is urging individuals to sign a government petition demanding "tougher standards for sewage infrastructure."
SOLAR’s petition, titled "Ensure new sewage treatment infrastructure meets higher standards as in the EU," has already garnered over 38,000 signatures. To be considered for a Parliamentary debate, the petition needs to reach 100,000 signatures.
SOLAR Co-Founder Ian McNuff emphasized the urgency of the situation, stating, "This report shows exactly the kind of infrastructure gap the petition is about. Hogsmill’s upgrade to fix this has already slipped by years, on a site just upstream of a part of the river that has mass watersports and general recreational use and more recently became London’s first official bathing site on the Thames."
McNuff further highlighted the interconnectedness of the identified failings, noting that the delayed storm tank upgrade directly addresses the site’s inability to cope with current catchment flows. "We need higher standards for this infrastructure as they now have in Europe. Every signature on this petition adds pressure on the government to act in the best interests of people’s health and to protect our natural waters," he added.
The EA’s stated enforcement response to the breaches at Hogsmill STW is "Investigation," with the Agency indicating it "will now consider what enforcement action is appropriate."
With a newly designated bathing site at risk and a growing public demand for accountability, the spotlight remains firmly on Thames Water and the government to ensure the long-term health and safety of the River Thames.
SOLAR’s petition can be signed here.
Nub News has contacted Thames Water for a statement regarding the EA’s findings and the proposed course of action.
