Executive summary
The interim report for the first half of 2025 highlights several significant operational and compliance issues across water companies in England and Wales. Multiple microbiological detections were reported at treatment works operated by Southern Water, South East Water, and Bristol Water, with the Inspectorate generally concluding that operational processes were satisfactory but identifying potential weaknesses in sampling practices and infrastructure. Anglian Water faced regulatory scrutiny for failing to verify disinfection effectiveness at Gainsborough works, prompting recommendations for improved monitoring and validation arrangements.
Consumer complaints revealed systemic gaps in communication and escalation processes, with delays and mismanagement of water quality concerns underscoring the need for coordinated responses across company teams. In Wales, two notable events occurred: a “do not drink” restriction affecting eight properties due to backflow contamination from a toilet cistern, and a precautionary boil water notice following a private supply leak. Both incidents emphasized the importance of plumbing compliance and ingress risk assessments.
Several operational audits identified deficiencies in asset management and process control. At Bolton Hill works, inadequate functional testing of alarms and low iodine numbers in granular activated carbon pesticide removal processes led to recommendations for enhanced monitoring and accelerated media regeneration. Other events included discolouration complaints linked to inaccurate asset records and turbidity failures caused by lime build-up in treated water tanks, reinforcing the need for risk-based maintenance strategies.
Industry-wide lessons emerged from enforcement actions and technical audits, with the Inspectorate issuing 74 regulation 28(4) notices and two undertakings during the period. These notices primarily addressed overdue reservoir inspections, disinfection policy deficiencies, and microbiological compliance failures. Additional enforcement targeted identified risks from PFAS, requiring Wessex Water to install temporary treatment and accelerate long-term mitigation measures.
The report gives advice to companies that must strengthen risk management, improve consumer communication, and maintain robust operational controls to ensure regulatory compliance and protect public health. Recurring themes include the need for proactive asset maintenance, comprehensive monitoring of disinfection and chemical dosing processes, and effective contingency planning for water quality events.