Many complaints were about affordability, after customers saw steep hikes to bills.
The number of complaints made by households about water companies to the industry watchdog has risen by a record 84% in a year, driven by customer concern and confusion over rising bills.
The Consumer Council for Water (CCW) said the year-on-year increase was the highest in its 20-year history and showed "just how dissatisfied" many people were.
Water customers in England and Wales have been hit with steep price hikes in recent years. The regulator Ofwat has also allowed firms to put up bills by 36% between 2025 and 2030 .
Water UK, which represents firms, said it understood that higher bills was never welcome, but the money was needed "to fund vital upgrades".
The total number of complaints to the watchdog rose to 15,115 in 2025-26, from 8,235 in the previous year.
Meanwhile, complaints made by households directly to water companies, which is required before complaining to the CCW, rose by 56% to 321,347.
The top three subjects of complaints to the CCW were measured billing, affordability and billing admin.
Mike Keil, the chief executive of the CCW, said the figures "reflect just how dissatisfied many people still are with the state of the water sector".
He said customers are "impatient to see the benefits" of higher bills.
"Companies need to be clear and open with their customers about how they are investing people's money to deliver real improvements."
The CCW assessed each water company's performance on the number of complaints it received for every 10,000 households it serves, and the amount of effort customers have to put in to get their complaint resolved.
Thames Water and South West Water rated "poor" for both performance measures.
David Bird, retail director at Thames, apologised to customers who "have not received the service they should expect".
"We know bill clarity has been a particular source of frustration, which is why we have launched a programme to redesign them, so they are easier to understand," he said.
Bills for the average Thames customer rose by 31% in 2024, but were a lot smaller this year at 3.4%.
Reporting synthesized and verified under Nexvoro.tech editorial guidelines. Full primary records referenced via BBC Business.
OpenAI has formed a new independent mathematics advisory group hosted at the Institute for Advanced Study in Princeton following a surge in automated problem-solving. The move arrives amid mounting academic scrutiny regarding the rapid pace of artificial intelligence in advanced mathematical research.
As debate intensifies over the rapid acceleration of artificial intelligence, OpenAI has proposed a comprehensive framework for international safety standards, focusing heavily on alignment research and recursive self-improvement. The move follows recent high-profile departures and escalating concerns from industry insiders regarding humanity's long-term control over advanced frontier models.
As Washington fiercely debates artificial intelligence oversight, Nvidia CEO Jensen Huang has emerged as President Donald Trump's top confidant, successfully pushing back against growing regulatory pressures. While rival tech executives advocate for government slowdowns, the head of the world's most valuable chipmaker is charting a rapid course for American tech supremacy.
