Cranleigh Sewage Concerns: Ofwat Response Raises More Questions Than Answers

Local Lib Dem Councillor Liz Townsend is continuing to push for answers after serious concerns were raised about sewage discharges and monitoring failures at Cranleigh Sewage Treatment Works.

Cllr Townsend, Waverley Borough Council’s Portfolio Holder for Planning and Economic Development, recently submitted a formal complaint to Ofwat regarding a prolonged failure of critical monitoring equipment at the site on Elmbridge Road.

Event Duration Monitoring (EDM) devices are supposed to provide real-time data on sewage discharges into local waterways. However, at Cranleigh, the monitor was offline for around six months in 2025 — leaving residents in the dark about what was being released into Cranleigh Waters.

During this period, local water rangers reported repeated signs of pollution, with independent testing indicating high levels of E. coli and elevated nutrients such as phosphates and nitrates.

In response to Cllr Townsend’s complaint, Ofwat confirmed that it is monitoring Thames Water’s compliance with its legal duties and has been in ongoing discussions with the company. The regulator also acknowledged that Cranleigh was one of the sites where Thames Water had previously breached its obligations, contributing to a £104 million enforcement penalty issued in 2025.

However, Ofwat stopped short of answering several key questions.

Crucially, it did not confirm whether the six-month outage of the monitoring equipment constituted a breach of the law. Nor did it address concerns about inaccurate discharge data reported by Thames Water during the period when the system was known to be faulty. 

While Ofwat stated that the monitoring device is now operational again, it has only been reliably back online since November 2025 — leaving a significant gap in public data and accountability.

The regulator also confirmed that delays to vital environmental improvements at the site — including a phosphorus reduction scheme originally due in 2024 — are part of an ongoing investigation. Thames Water now expects this work to be completed in 2028.

Cllr Townsend has now written back to Ofwat seeking clearer answers, including whether enforcement action will be taken, what level of monitoring failure is considered acceptable, and how regulators will ensure accurate reporting in future.

Commenting, Cllr Townsend said:

“It is simply not good enough for monitoring equipment to be offline for months while residents are left worrying about the safety of their local waterways. Transparency and accountability are essential, and at the moment both are lacking.

Ofwat’s response confirms that there are serious concerns, but it fails to answer the most important question — whether Thames Water has actually broken the rules.

Residents deserve clear answers, proper enforcement, and urgent action to protect Cranleigh Waters.”

Waverley Liberal Democrats will continue to press both Thames Water and regulators until residents can have full confidence that local waterways are being properly monitored and protected.