Groundwater-Related Risk Assessment - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 758

groundwater is a very important protection target. Moreover, water is used in several
other domestic applications, for example, for dish and clothes washing, showering
and toilet flushing. Although the water quality requirements for these applications
are much less demanding, in most countries the same water supply is used for these
as is used for drinking water. Only a few countries in the world - Singapore and
Hong Kong, for example - have separate water supplies for toilet flushing. Anderson
( 2003 ) illustrated that water reuse in agriculture, urban areas, industry and water
resource supplementation has substantial environmental benefits for Australia, such
as in reducing the impact of wastewater discharges on environmental water quality.
The authors also demonstrated how water reuse has economic benefits.
Groundwater bodies represent a huge reservoir for domestic water supply. In
the European Union, for example, circa 70% of the piped water supply is provided
from groundwater (Foster and Chilton 2003 ). Worldwide, this percentage equals at
least 50% (Zektser and Everett 2004 ). In fact, with a global withdrawal rate of 600-
700 km 3 /year, groundwater is the world's most extracted raw material (Zektser and
Everett 2004 ).
Using groundwater as a resource for domestic water supply has many advantages.
Firstly, in most inhabited parts of the world there is a large amount of groundwater.
In spite of the huge volumes withdrawn, subtracted water volumes often are readily
supplemented. The second advantage of groundwater as a source for domestic water,
and most certainly for drinking water, is that the upper soil layers function as a
filter, physically, chemically and biologically (for the latter, see Section 13.4.3.5 on
the ecological cleaning function). This natural cleaning function is effective and
cost-efficient. Thirdly, groundwater use often brings great economic benefits per
unit volume compared with surface water because of ready local availability, high
drought reliability and a generally good quality requiring only minimal treatment
(Burke and Moench 2000 ).
Groundwater is also used for agriculture and industrial purposes, in much larger
quantities, in fact, than the domestic use of groundwater. Groundwater volumes used
for recreational purposes (including golf courses) is relatively limited but growing.
Worldwide, clean water resources have come under increasing pressure. Since
the 1960s, the worldwide demand for water has increased significantly. Gradually,
more humans are requiring more domestic water per individual. Industrial and agri-
cultural demands have also increased during the last few decades. In contrast, the
amounts of clean groundwater have slowly decreased due to desiccation, salin-
isation, acidification, and, last but not least, groundwater contamination (due to
excess nutrients from diffusely contaminated sites, and (predominantly mobile) met-
als and organic contaminants from point sources). To be specific, in dry regions,
over-exploration of groundwater resources has resulted in severe problems of sub-
sidence of land, and destruction of vegetation and soil life, due to the effects from
extreme drought in the soil upper layers. In many inhabited regions of the world,
clean groundwater is becoming scarce due to soil contamination. An interesting
indicator for the increased value that clean water has is the fact that financial insti-
tutions in many countries now offer possibilities for financial investment in clean
water.