The ecologist Anthony Allan of London King’s College has developed the concept of 'virtual water' for the total water quantity which is used during the manufacture a product.
Summarized is the quantity of clean water which evaporates, is consumed or contaminated at the production of a product - from watering the raw material plants to the cooling water of the machines used.
If the so-called 'water footprint' of various products is calculated, a by far higher water consumption results, than might be sought at first sight.