Underperforming web sites could be costing UK councils £11m a month collectively as people turn to costly offline channels for information, according to local government IT body Socitm.

Data collected in September by Socitm Insight’s Website Takeup service showed that 42 per cent of visitors to council web sites did not find everything they were looking for, with half of these not finding anything they were looking for.

On average this means 20,000 unsatisfied visitors per month for single tier and county council sites and up to 5,000 for shire district councils with a total of nearly 4.4 million enquiry "failures" in one month, according to the body.

Assuming each of these web failures led to a subsequent phone call to the council, which cost an average of £2.50 each, the total cost of these failures is £11m per month, said Martin Greenwood, programme director for Socitm Insight.

"We have been drawing attention to the level and consequences of local authority web enquiry failures for some time," he said.

"With the coming cuts in public spending, councils must invest in their web channel to save money through self-service, rather than adding uneccessary cost because customers can’t actually do what they want to online."

The survey also found the web is the most important customer access channel by volume of enquiries. In the same month 70 per cent of initial customer interactions came from the web site, 17 per cent from the telephone and 13 per cent were face-to-face.

But the online channel is also the least satisfactory - 42 per cent of visitors rated it as poor, compared with 21 per cent when rating face-to-face contact and two per cent when rating phone contact.

And the failure of people to find the information they need on the web is getting worse, increasing by 10 per cent in the past 12 months, with net visitor satisfaction falling nearly 14 per cent.

Socitm is running a Customer Access Improvement Service that enables councils to measure and benchmark their performance on customer satisfaction and value for money across a range of communication channels.