The Ingenieur Vol 57 January-March 2014 The Ingenieur Vol 57 January-March 2014 | Seite 30

INGENIEUR
resources by importing waterintensive goods, rather than
using scarce indigenous water
supplies to produce goods with
high-embedded water content.
The World Bank subsequently
started to refer to this idea as
the ‘water, food and trade’ nexus
in the mid-1990s.
DPI views virtual water as
a measure of the total water
consumed in producing and
delivering a good or service.
Virtual water is referred to
as ‘embedded water” as its
represents the water used in
the whole production chain
embedded in the end-products
rather than the actual water
content of the finished product.
The total amount of water
required to produce a particular
quantity of output will depend
on the prevailing production
conditions, including place and
time of production and efficiency
of water usage.
To further illustrate the
amount of water it takes to
produce various foodstuffs,
David Pimentel, Laura Westra
and Reed F. Noss produced the
following table in their paper,
Ecological Integrity:
Potatoes: 547 litres a kg
Wheat: 986 litres a kg
Corn: 1,534 litres a kg
Rice : 2091 litres a kg
Soybeans: 2,191 litres a kg
Beef: 109,671 litres a kg
The UN recommendation of the
annual requirement of water per
person is between 5,000 gallons
and 10,000 gallons. Although
water is a renewable resource,
the number of fresh water
sources remains a constant.
However, from the demand side,

6
28

Water stress region is only suitable for less water intensive product

VOL 57 JANUARY-MARCH 2014
VOL 55 JUNE 2013