PN 14/20: Customer survey results set the scene for best performers in the water sector


Dŵr Cymru has topped the customer measure of experience (C-MeX) league table with Portsmouth Water in second, and Wessex Water in third place.

The bottom performers are Thames Water, Southern Water and Affinity Water, with Affinity Water also placing second to last place in the developer services measure of experience (D-MeX) league table. In contrast, in addition to performing well against C-MeX, Portsmouth Water topped the D-MeX table, followed by Wessex Water in second and Northumbrian Water in third place.

C-MeX focuses on companies to improve the experience of their residential customers, while D-MeX looks at the experience for developer services customers, such as property developers requesting a new connection. Both measures aim to drive up the customer experience by incentivising good performance and penalising poor performance.

The results for both C-MeX and D-MeX were obtained from information gathered from interviews with customers during 2019-20, which was a pilot for the new incentive mechanisms. While financial incentives do not apply to these results, these scores indicate how the sector is currently performing and set the baseline future years.

Now that C-MeX and D-MeX are in full effect, companies stand to incur significant underperformance payments or outperformance payments based on how they score against each other each year starting in 2020-21. With the largest company facing returning up to £20m a year to its customers if it performs poorly.

Aileen Armstrong, Senior Director at Ofwat, said:

“Customers rightly expect companies to provide an excellent level of service and today’s scores provide a strong indication of which companies are doing well and which companies need to step up a gear to provide an improved level of service. We are confident that C-MeX and D-MeX will encourage companies to deliver better customer experiences while also measuring performance across companies consistently, reliably and fairly.”



Notes to editors:

  1. C-MeX and D-MeX shadow year scores
  2. BMG research
  3. C-MeX is based on two surveys conducted each month with residential customers:
  • the customer service survey (CSS) – based on interviews with a random sample of customers that have recently contacted their company, using a mixture of telephone and online surveys; and
  • the customer experience survey (CES) – based on interviews with a random sample of members of the public, using a mixture of telephone and face-to-face surveys.
  • 80% of each company’s C-MeX score is based on the customer satisfaction score and, for this shadow year – a further 20% on the net promoter score where customers are asked how likely they are to recommend their water company.
  1. D-MeX has two components which measure the service provided by water companies to their developer services customers (which include large and small property developers, self-lay providers, new appointees and other customers requesting a new connection):
  • a qualitative component – based on monthly interviews with developer services customers that have transacted with a water company in the previous month
  • a quantitative component – based on the water company’s performance against a key set of Water UK metrics which measure the service provided by water companies to their developer services customers.