Buying in bulk can cost a packet

Supermarket shoppers who buy in bulk to save money can often end up paying more, an investigation has found.

Stores have been found charging up to 30 per cent extra for multi-packs than for the same product bought in smaller quantities or individually.

In some cases it is cheaper to buy six individual bottles of water than a six-pack, or two 500g bags of rice than a 1kg pack.

While retailers insisted that this was not deliberate, experts said yesterday that the practice takes advantage of the assumption that buying multi-packs or large containers is more economical.

Safeway and Tesco were the biggest culprits among the 30 supermarkets surveyed. In total, around 10 per cent of bulk products checked offered either no discount or actually proved more expensive.

Analysts accused the supermarkets of incompetence at best. They said that the practice would have cost shoppers thousands of pounds and warned them to check every price.

'It's not treating the customer with much respect,' said Richard Perks, director of retail research at Mintel.

'Most people assume bulk buying is going to be cheaper and don't check.'

Prices were studied at shops in London, Manchester, Glasgow, Birmingham and Bristol, as well as smaller towns including Bury St Edmunds, Suffolk, and Taunton, Somerset. At a Tesco in central Birmingham, a six-pack of 1.5-litre Vittel water cost £3.49. However, six separate bottles cost £3.24.

At Safeway in Harborne High Street, Birmingham, a pack of two, two-litre bottles of Coca-Cola cost £2.93. Buying two bottles individually cost £2.56.

Although the problem was less pronounced at Sainsbury's, the biggest single mark-up was found at its store in Vauxhall, South London, where 540g tins of carrots cost 28 per cent more per kilo than 300g tins. Tins of potatoes showed a similar price difference.

The next biggest mark-up was for Branston pickle at Tesco, which cost 19 per cent more when bought in bulk.

At Waitrose, bulk buying could normally be relied on to offer a discount. However, some products such as Stella Artois lager were still found to be cheaper when bought in smaller pack sizes.

The supermarkets said the problem was rare and the prices would be corrected within days.

Sainsbury's said: 'There are always a few that run slightly behind if there is a price change - it can take a while to catch up.'

Tesco said: 'Fierce price competition means prices are going down all the time. The handful of products identified have taken a little longer to fall into line.'