Although covering some 70% of the Earth's surface,
most water is saline. Freshwater is available in
almost all populated areas of the earth, although it
may be expensive and the supply may not always be
sustainable. Sources where water may be obtained
sources such as groundwater, hyporheic zones and
precipitation which includes
rain, hail, snow, fog, etc.
surface water such as rivers,
biological sources such as
the sea through desalination
Water supply network
Spring water, a natural resource from which much
bottled water comes, generally contains minerals. Tap
water, delivered by domestic water systems in
developed nations, refers to water piped to homes
through a tap. All of these forms of water are
commonly drunk, often purified through filtration.
The most efficient way to transport and deliver
potable water is through pipes. Plumbing can require
significant capital investment. Some systems suffer
high operating costs. The cost to replace the
deteriorating water and sanitation infrastructure of
industrialized countries may be as high as $200
billion a year. Leakage of untreated and treated water
from pipes reduces access to water. Leakage rates of
50% are not uncommon in urban systems.
Because of the high initial investments, many less
wealthy nations cannot afford to develop or sustain
appropriate infrastructure, and as a consequence
people in these areas may spend a correspondingly
higher fraction of their income on water. 2003
statistics from El Salvador, for example, indicate
that the poorest 20% of households spend more than 10%
of their total income on water. In the United Kingdom
authorities define spending of more than 3% of one's
income on water as a hardship.
The Millennium Development Goal of halving the
proportion of people without access to safe drinking
water between 1990 and 2015 will probably be reached.
Some countries though still face enormous challenges.
Rural communities are the furthest from meeting the
2015 MDGs drinking water target. Globally only 27% of
the rural population has water piped directly to their
home and 24% rely on unimproved sources. Of the
884 million people without access to an improved water
source, 746 million people (84%) live in rural areas.
Sub-Saharan Africa has made the least progress in
improved water sources since 1990, improving only 9%
to 2006. In contrast, the Eastern Asian region saw a
dramatic drop from 45% to 9% reliance on unimproved
water in the same time period.