Frozen food companies could be in line for windfalls of up to a million pounds after the British Frozen Food Federation vowed to help stop water suppliers mischarging.

The BFFF has joined ­forces with Water Audit Services, who provide a free service to help companies reduce their water charges. WAS will carry out an appraisal of a company's charges over the previous 12 months, then step in to make savings, or potentially obtain refunds from suppliers. Companies can review bills going back six years.

"One in two businesses is incorrectly charged by their water supplier and one in four is seriously overcharged," said Gareth Vaughan, senior business development manager at WAS. "Our audits have produced refunds and savings from a few thousand pounds to over £300k."

"Water is an ever-increasing cost for producers, wholesalers and retailers," added Brian Young, director general of the British Frozen Food Federation.

Meanwhile, the BFFF also announced its intention to change to a limited by guarantee legal entity and has commenced voting on the issue. It said the change was because "when banks and creditors look at BFFF's activities they see us as something akin to a tennis club."