Complaint performance

We share information with household customers about how their water companies handle complaints each quarter. This data comes from complaints made directly to the water companies and those reported to us.

How we measure performance

For this quarterly complaints update, we use two sources to understand how companies are performing with complaints:

complaints received directly by the companies; and
complaints raised directly to CCW about the companies

This update focuses on the complaints performance for the current year, 2025-26.

How we compare performance

To compare companies of different sizes, we use a metric called ‘complaints per 10,000 connections’. This metric takes into account the number of water and wastewater connections each company serves.

For example, if Company A received 600 complaints and has 4,000,000 total connections, the calculation would be:

Complaints per 10,000 connections = 600/4,000,000 x 10,000 = 1.5

Comparative performance: we compare the performance of individual companies within their respective segments as either Water and Sewerage Companies (WaSCs) or Water Only Companies (WOCs).

Important note: the data in this publication is unaudited and a subject to change at the end of the year.

How we measure
Quartile 1 – Good
Quartile 2 – Better than median*
Quartile 3 – Worse than median*
Quartile 4 – Poor

*Median – a mid-point of the data set, or a middle value in the list of numbers that are arranged by highest to lowest.

Water and sewerage companies’ performance in 2025-26 (April to June 2025)

Company	Household connections	Complaints to company	Per 10k (company)	Complaints to CCW	Per 10k (to CCW)
Anglian Water	3,112,980	2,843	9.13	123	0.40
Dŵr Cymru Welsh Water	1,504,167	2,389	15.88	104	0.69
Hafren Dyfrdwy	101,194	49	4.84	5	0.49
Northumbrian Water	1,275,308	1,385	10.86	27	0.21
Severn Trent Water	4,386,041	3,977	9.07	498	1.14
South West Water	1,029,624	5,005	48.61	175	1.70
Southern Water	2,088,159	5,646	27.04	266	1.27
Thames Water	6,043,396	25,632	42.41	1,239	2.05
United Utilities	3,390,859	8,772	25.87	229	0.68
Wessex Water	1,286,235	1,499	11.65	31	0.24
Yorkshire Water	2,399,641	8,176	34.07	252	1.05

Water only companies’ performance in 2025-26 (April to June 2025)

Company	Household connections	Complaints to company	Per 10k (company)	Complaints to CCW	Per 10k (to CCW)
Affinity Water	1,520,312	3,936	25.89	161	1.06
Bristol Water	530,130	625	11.79	15	0.28
Cambridge Water	143,800	258	17.94	14	0.97
Essex & Suffolk Water	800,302	1,224	15.29	22	0.27
Portsmouth Water	311,663	157	5.04	4	0.13
SES Water	289,973	563	19.42	45	1.55
South East Water	1,022,450	1,856	18.15	70	0.68
South Staffs Water	577,105	1,057	18.32	48	0.83

Complaint trend

Below, you’ll find graphs that track how company complaint trends changed over time. First graph shows complaints received by company per 10,000 connections, while the other illustrates complaints reported directly to CCW per 10,000 connections.