Many of the complaints are down to billing and charges

More than 240,000 complaints were made during the financial year of 2006/07 - an increase of 30% compared with the previous year.

The Consumer Council for Water said most came from customers of three firms - Thames Water, United Utilities and Severn Trent.

Almost half of the complaints were about bills and charges.

Five companies - South East, Southern, Mid Kent, Sutton and East Surrey and Hartlepool reported more than 100% increase in customer complaints in the report, called Complaint Handling in the Water Industry in England and Wales 2006/07.

The Consumer Council for Water said water customers were becoming "increasingly demanding of their companies" and also wanted complaints correctly dealt with "first time".

Billing problems

Council chief executive Tony Smith told the BBC customers have already had "pretty high price increases".

He said: "They see companies making good profits and they expect to see the service go with that.

Last year, one of the top complaints was about not being able to get through to us on the phone Martin Kane, Severn Trent

"It's mainly to do with the poor performance of three or four companies, particularly on billing and putting new billing systems in place."

Mr Smith added that the complaints were only a small proportion of the "millions" of customers the water companies served.

"There are some very good performers in there, it's not to say the industry as a whole is failing.

"But the problem is, particularly with companies who have introduced new systems for working out the bills for customers and sending those bills out, including Severn Trent, South East Water and Southern, their complaints are actually up by several times over the previous year and they stand out as the poor performers."

Mr Smith also said the "perpetuating problem" was that customers received bills they did not understand or that were wrong, attempted to call to resolve the issue but found call centres blocked because of the high volume of people contacting the company.

Severn Trent says it is confident that "real progress has been made" to reduce the numbers of customer complaints.

Customer Relations Director Martin Kane said: "We are aiming for a 30% reduction in total complaints by next year and are confident that our focus on better training and recruitment of skilled staff is having a direct impact.

"Last year, one of the top complaints was about not being able to get through to us on the phone - that accounted for almost one third of all complaints.