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In the Malvern hills water from the Primeswell Spring is delivered through steel pipes to the processing plant a few miles away in Colwall, Worcestershire.

A team of 23 employees at the Coca-Cola Enterprises factory oversee the distribution of water from tanks into polyethylene terephthalate (PET) bottles, which, the environmentalists will be unhappy to hear, are delivered from a factory in Barnsley.

They are then film-wrapped into crates of 24. About 1.3 million such cases will be produced every year. Ian Hall, the former chairman of the Natural Mineral Waters Association, estimates that every bottle produced releases the equivalent of 120-180 grams of carbon dioxide. That’s 156 million grams from the small Colwall plant alone.

On top of this where do the bottles end up when they are empty? Although PET bottles weigh 30 per cent less than they did 15 years ago, recent government figures show that more than a third of the plastic collected by local authorities, supermarkets and businesses – 200,000 tonnes a year – are being transported to China.

These shipments, often illegal, are sorted by hand in cities such as Taizhou in Zhejiang province by families so poor they are eager to earn just a few dozen yuan (a couple of pounds) a week sifting through the detritus.

Not such pure mineral water after all, say the critics.

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