Thames Water Utilities Limited (“TWUL”) has today asked its economic regulator, Ofwat, to refer its Final Determination to the Competition and Markets Authority (CMA) for a redetermination.

The Board of the UK’s largest water and wastewater services company made this unanimous decision after concluding that the Final Determination for the regulatory
period 2025 to 2030 does not appropriately support the investment and improvement that is required for Thames Water to deliver for its customers, communities and the
environment for the next five years.

The Chairman of Thames Water, Sir Adrian Montague said: “We have taken the decision to refer our Final Determination to the Competition and Markets Authority in the interests
of our customers and the environment. We are focused on putting the business on a long-term stable footing so we can succeed in our turnaround, and build and maintain an infrastructure that supports growth and can withstand the effects of climate change.

“We put forward a realistic business plan for 2025-2030 that addressed our customers’ and stakeholders’ priorities such as providing safe and resilient water supplies and
improving performance. After careful consideration, our analysis shows that our Final Determination for the next regulatory period will continue to impact our ability to fund the
improvements our customers and the environment so rightly want and deserve.”

The challenges of its Final Determination

Throughout the Price Review 24 (PR24) process, Thames Water has engaged with Ofwat to seek to secure a Final Determination that recognises its current position and supports its turnaround. While there has been progress, after a thorough review, it is clear that there remain significant gaps between the Final Determination and what it needs to deliver for customers and the environment. In its referral to the CMA, it is seeking:

• A regulatory settlement that reflects the circumstances of Thames Water’s operating area
• Targets that are challenging but achievable
• An appropriate balance of risk and return

There will be no delay to the delivery of Thames Water’s plans for year one of AMP8 as a result of this referral. Customer bills for 2025-26 will be unaffected.

Full details of its statement of case will be provided to the CMA in due course and in line with the process timetable.