As much as eight per cent of business data storage costs may be incurred through archiving non-business related material, a new study has claimed.

Of the 630 IT directors surveyed by Hitachi Data Systems, a quarter reported that emails now account for more than 20 per cent of their companies' entire data storage capacity.

Some firms now believe that emails account for up to 40 per cent of data storage costs, with an estimated one in five defined as non-business related.

Personal emails are contributing to the rising cost of data storage as firms move towards retaining all emails to be sure of complying with regulations such as the US Sarbanes-Oxley Act.

"Since most companies are reluctant to place draconian email restrictions on their staff, they need to look at ways of storing email content more efficiently," said Nick Howe, services director at Hitachi Data Systems, in a statement.