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 – At or 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 September 2025)

Company	Household connections	Complaints to company	Per 10k (company)	Complaints to CCW	Per 10k (to CCW)
Anglian Water	3,112,980	6,770	21.75	315	1.01
Dŵr Cymru Welsh Water	1,504,167	5,671	37.70	252	1.68
Hafren Dyfrdwy	101,194	85	8.40	10	0.99
Northumbrian Water	1,278,357	3,012	23.56	59	0.46
Severn Trent Water	4,386,041	9,026	20.58	929	2.12
South West Water	1,029,624	11,145	108.24	376	3.65
Southern Water	2,088,159	11,153	53.41	567	2.72
Thames Water	6,043,396	55,158	91.27	2,430	4.02
United Utilities	3,390,859	14,494	42.74	456	1.34
Wessex Water	1,286,235	3,342	25.98	61	0.47
Yorkshire Water	2,399,641	15,770	65.72	517	2.15

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

Company	Household connections	Complaints to company	Per 10k (company)	Complaints to CCW	Per 10k (to CCW)
Affinity Water	1,520,312	8,266	54.37	323	2.12
Bristol Water	530,130	1,382	26.07	27	0.51
Cambridge Water	143,800	469	32.61	26	1.81
Essex & Suffolk Water	800,777	2,506	31.29	64	0.80
Portsmouth Water	311,663	352	11.29	16	0.51
SES Water	289,973	1,058	36.49	93	3.21
South East Water	1,022,450	3,999	39.11	162	1.58
South Staffs Water	577,105	1,690	29.28	92	1.59

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.