Household complaints to the water customer watchdog have surged to a nine-year high following the steepest bill increases since the industry's privatisation.
The Consumer Council for Water (CCW) said complaints from household customers in England and Wales rose for the third consecutive year, up three per cent to 8,235 from 7,977 in 2023-24, the highest number of complaints in almost a decade.
The rise in complaints occurred despite an encouraging eight per cent fall in the overall number of complaints made directly to water companies – down to 205,853 from 222,956.
Customers must give their water company two chances to resolve an issue, after which they can escalate it to CCW for review.
CCW named Thames Water, Yorkshire Water, South West Water, Affinity Water and SES Water as the poorest performing firms based on complaints it received over the last year.
However, Wessex Water, Portsmouth Water and Bristol Water topped the rankings.
Billing problems accounted for the majority of grievances, representing 63 per cent of complaints made to water companies and 66 per cent of those escalated to CCW.
Among those lodged with CCW was a 138 per cent rise in complaints about the scale of bill increases, while the number of people saying they could not afford the higher charges jumped by 39 per cent.
The spike follows the largest single-year increase in household water charges since privatisation, announced in January, which increased the average household water and sewerage bill from under £500 to more than £600 a year.
However, households have been hit particularly hard since April with an average hike of £86 or 20 per cent front-loaded into the coming year, with smaller percentage increases in each of the next four years.
Factoring in inflation, which is added to bills each year, the 2025-26 increase in the average bill is £123, or 26 per cent.
In return, the sector has pledged to deliver a record five-year package of investment to improve services and clean up rivers, streams and seas.
CCW also reported a significant rise in complaints about poor experiences with smart meter installations – up 48 per cent on the previous year.
While complaints handled by CCW about environmental issues fell 31 per cent, they remained well above previous levels amid continuing anger over pollution from storm overflows.
“Although it’s encouraging to see complaints to water companies falling, more households are turning to CCW for help than at any point in the last nine years, CCW chief executive Mike Keil said.
“Bills remain the top concern for households, and we can see April’s unprecedented price rises are already hurting a lot of people.
“Clearer communication from companies could prevent many of these complaints by helping customers understand how their money is being spent and what support is available if they are struggling.
“Seeing is believing: if people are paying more for their water, they need to see real improvements in the services they receive.”
A spokesperson for Water UK, which represents firms, said: “The fall in complaints, including an 8 per cent overall reduction, more resolved at the first attempt and 31 per cent fewer pollution-related cases, shows companies are making progress for customers.
“Escalations to the Consumer Council for Water this year reflect concerns with higher bills, which are necessary to secure our water supplies, end sewage entering our rivers and seas and support economic growth.
“We understand that bill increases are never welcome and recognise they are difficult for many households. That’s why water companies are more than doubling the help available, with £4.1 billion in financial support put forward over the next five years.
“The industry remains committed to improving communication with customers and showing clearly how their money is being used to deliver the improvements they expect.”
The latest complaints figures follow regulator Ofwat reporting that two UK water firms will have to pay out more than £86 million worth of enforcement packages over failures linked to wastewater spills.
Ofwat said failures by Anglian Water and South West Water in maintaining storm overflows and their sewage networks were “unacceptable”.
