A body representing the customers of water companies says complaints have risen by almost a third because concerns are not being addressed.
The Consumer Council for Water (CCW) says it has handled 7,977 complaints in the last year from people who had “exhausted” their company’s complaint process.
It found Thames Water to be the worst performer, with Yorkshire Water and Cambridge Water also poor.
Thames Water and Yorkshire Water say they are working with CCW to make changes. Cambridge Water has been contacted for comment.
According to CCW, there has been a 29% rise in complaints compared to the previous year, with households making 222,956 complaints to water companies in England and Wales during 2023-24.
Billing disputes made up more than half of complaints, though concerns about environmental performance, such as spills from storm overflows and pollution, increased by 217%. Complaints relating to water meters also rose.
Chief executive Dr Mike Keil said: “Households are having to waste far too much time and energy resolving complaints, which water companies should be getting right first time.
“Trust in the water sector is already badly fractured and the poor handling of complaints will only compound people’s frustration.
“We’re particularly concerned to see a significant rise in complaints from customers with water meters who are questioning the accuracy of their bill.
“More companies are planning to roll out smart meters over the next few years, so they must listen and act on people’s concerns now or risk further damaging customer trust.”
CCW compared the performance of water companies on the number of complaints received per 10,000 household connections, and also assessed how well they were handled. Thames Water, Yorkshire Water and Cambridge Water rated as poor on both counts.
However, Wessex Water and Portsmouth Water received top marks on the same metrics.
David Bird, retail director at Thames Water, said: “CCW have recognised the collaborative approach we have taken and that the improvements we are making are showing promise. However, we recognise we have more to do.
“Our turnaround plan is focused on resolving customer complaints and improving the quality of their interaction with our business, from first contact through to resolution.”
He said the company had an “ambitious business plan” based on customer feedback and insight.
“Our customers told us to focus on delivering safe and resilient water supplies, address concerns over our overall performance including on customer service, and deal more effectively with wastewater,” he said.
“Our aim is to always deliver excellent customer service, and we’re determined to do better.”
Imran Patel, group customer experience director at Yorkshire Water, said: “We work really hard to make sure we do the right thing for our customers and we’re continuing to invest in new systems, training for our customer experience teams and our reporting to ensure we improve the service our customers receive.
“We have worked closely with CCW to audit our complaints process and have received positive feedback for our customer-focused culture and the speed and effectiveness of complaints resolution.”
He said the company had a series of investments lined up to improve the customer experience, and that it was committed to “improving Yorkshire’s environment and ensuring no household or business should be without reliable, safe, clean water”.
Water UK, the trade association for the water industry, said companies were working hard to “provide the drinking water that is independently rated the joint-highest standard in the world”.
It said a rise in customer complaints should be examined, but “not all complaints are necessarily evidence of poor service”.
It added: “A better measure is the number of complaints sent by the CCW to adjudication, which fell 37%, from 153 late last year to 57 for the equivalent period this year.”
It said firms were also being affected by funding cuts from water regulator Ofwat, which needed to “enable companies to provide [customers] with the service they rightly expect”.
Water companies have put forward plans for bill increases, although Ofwat has made proposals to cap them. It is due to make a final decision in December.