Water, water, everywhere .... except when it bottles it.

The rising global demand for water is pushing this essential human requirement higher up the list of critical resource exploitation issues. A number of concepts are being applied to water that in previous generations viewed the resource as ubiquitous, renewable and led to its squander.

Water stress: when there is insufficient water for all the uses to which it may be put. It is generally regarded as being between 1000-1700 cu.litres of water available per person per year. Less than 1000 cu. litres - and the situation is one of water scarcity.

Water security: having access to a sufficient volume of clean, potable water for the domestic, industrial, commercial and agricultural needs of an area. Water security may be placed under threat if the demand rises significantly, if there is physical reduction in replenishment - such as reduced precipitation, or if a neighbouring user upstream increases extraction or pollutes the water that flows into a region.

Cross-boundary water transfer: usually involves a large-scale engineering project in re-directing water from one region or country into another neighbouring one. The implications for natural ecosystems can be significant.

Water footprint: similar to a carbon footprint - it quantifies the total amount of water used and put beyond further use in a consumption area or specific activity. The water footprint of a city is not just the water domestically consumed, but used in industry, commerce, agriculture plus the effect of effluent that exits the city and contaminates other fresh water sources - either surface or groundwater supplies.

The Virtual Water Trade: the concept of 'virtual water' is a relatively new one. It considers the total water used in the production of a commodity (peaches) or product (a car), and if those items are then exported abroad, they take their 'virtual water' component with them. It's a concept that questions whether regions that experience water stress (southern Spain) should produce and export high-water-content produce such as salad crops to wetter countries such as the UK as they are trading large volumes of 'virtual water' in the process.

See how many of these concepts are applicable to this article in 'The Economist' on the water demands of the bottled-water industry, and how China is quenching its thirst for additional water supplies.