Customer complaints about water and sewerage companies rose by nearly one third in 2006/07, according to figures from the Consumer Council for Water (CCW).
The first ever national set of statistics released on water complaints show that the number of dissatisfied customers rose from 185,466 in 2005/06 to 240,799 in 2006/07, an increase of nearly 30 per cent.
Three companies Thames Water, Severn Trent and United Utilities were responsible for over three-quarters of the complaints, with most unhappy about billing and charges.
But nearly one in six concerned more fundamental service issues involving supply, pipes and water quality.
CCW national chairperson Yve Buckland said the figures showed consumers were becoming "increasingly demanding".
"They see water companies making good profits and expect service, if not improving, then at the very least delivered to a good, consistent and reliable standard. They also want complaints dealt with 'right first time'," she said.
"We will be pushing water companies to improve these figures and provide a much better level of customer service, comparable with the best in other service sectors."
Last month water watchdog Ofwat said Thames Water faced a £12.5 million fine for its poor customer service and failing to provide it with accurate information.
The final level of the fine is expected shortly after the completion of a four-week consultation period. Ofwat said "sub-standard processes and systems" resulted in customers receiving a sub-standard quality of service.