Photo credit: Sharon Waldron
The Drinking Water Inspectorate has issued Thames Water a warning letter after finding “multiple and significant failures” in works that left a customer’s water supply mistakenly connected to a sewer in Kidlington, Oxfordshire. The letter, dated 23 July, follows the Inspectorate’s investigation into an incident that occurred on 4 March 2024.
What went wrong
The DWI found that Thames Water had failed to plan and risk-assess the connection works properly, had not identified or escalated uncertainty about the pipework, and had provided ineffective supervision while the connection was carried out. The result was a cross-connection, in which a property’s drinking water supply was wrongly joined to the sewer network, a serious contamination risk.
After the incident, Thames Water removed the contamination and made a number of operational changes to prevent a recurrence. These included standing down and rebriefing all staff involved in mains connections, and revising its procedures for that type of work.
Where the warning sits
The DWI issues warning letters where it judges that a company has fallen short of expected standards but that formal enforcement or prosecution is not appropriate. It cautioned that any repeat of a similar nature could lead to further sanctions, including enforcement action or prosecution. The Kidlington case joins a register of recent warning letters across the sector, which has included action against Severn Trent over microbiological failures at a treatment works. For Thames Water, already under intense financial and regulatory scrutiny, it is a further mark against its operational record.
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