Inspectors in London have discovered that bottled mineral water sold there could be almost two years old by the time it is bought by consumers.
Supermarket shoppers who buy bottled water believing it is fresher than tap water are unaware that it may in fact have sat on a warehouse shelf for most of its use-by date.
Professor Jeni Colbourne, head of London's Drinking Water Inspectorate, said: "People have a perception that bottled water is fresh because it's been sealed in a bottle, unsullied by human hands. But in fact it has probably spent most of that time in hot warehouses and on hot supermarket shelves."
In one warehouse, water was discovered which had been bottled up to 23 months ago. Water companies insist the airtight seals used on bottles mean they are still safe to drink even after two years.