Competition & Markets Authority Final Determination

The Competition & Markets Authority (CMA) has published its final decision on how much we can charge customers from April 2027.

This follows the review we requested back in February 2025 into Ofwat’s determination. The CMA’s Final Determination is broadly in line with the provisional findings it shared in October 2025. It allows modest further increases to the revenue we can raise compared with Ofwat’s original decision - showing that the appeal was worthwhile and the right step to take on behalf of our customers.
 
The Final Determination means the average bill will increase by a further 2.5% above Ofwat’s original allowance. However, these changes will not affect customer bills until 2027–28. As always, support will remain available for anyone who may struggle to pay. 

Southern Water’s CEO Lawrence Gosden said:

“We note the CMA’s publication of its Final Determination, following our request for a redetermination of our investment plans, and will now work through the detail carefully. We didn’t take the decision lightly to appeal against the original determination from Ofwat. We sought a fair settlement that would enable us to deliver the improved infrastructure and services Southern Water customers want and deserve. For any customers who may be struggling with their bills, we’re increasing the range of support we offer.

We’ll now continue to focus on delivering our unprecedented £8.5 billion investment plan.”