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Water
Quality Basics
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water
quality
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Water
is a basic requirement for survival whether it is for humans, other animals,
or plant life. To be usable by most living things, water has to be relatively
free of harmful substances such as pollutants and other contaminants. The
degree to which the water is free of undesirable substances is a measure
of its quality. The highest quality water is free of all harmful and undesirable
substances. |
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pure
water
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Absolutely
pure water contains no other substances of any kind other than water molecules.
Practically speaking, absolutely pure water represents an unattainable
standard: there will always be stuff other than water molecules in the
water we use. However, when people speak of pure water, they're generally
referring to high quality water that may or may not contain some innocuous
(not harmful) substances. Water that is billed as pure may actually
infer that the water contains an additional (supposedly) healthy component
that has, for example, some curative power.
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fresh
water
salt
water
pollutants
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Fresh
water refers to water that has probably been derived from the water cycle.
Fresh water's distinguishing characteristic is that it is very low in dissolved
salts, unlike ocean water whose high salt content makes it unsuitable for
a variety of uses including human consumption. Water having a high salt
content is known variously as saltwater, seawater, and saline. Fresh
water should not be assumed to be safe for human consumption just because
it is classified as fresh. It's entirely possible that fresh water,
say from a river, contains harmful pollutants. Additionally water may appear
to be crystal clear and odor free and still contain harmful bacteria. Therefore,
drinking water directly from untreated or untested sources is generally
not a good idea. |
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Treatment
is typically required to produce potable water.
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The
term describing water fit for human consumption is potable. (Pronounced
po-tah-bul.) Potable water is safe for drinking and cooking. Our tap
water is assumed to be potable; federal laws require that minimum quality
standards be met. Fresh water from environmental sources is typically treated
to remove or neutralize undesirable compounds so that it becomes potable.
But it's possible for potable water to contain substances that don't taste
or smell very good or even be cloudy or slightly muddy looking. Although
the water quality is acceptable from a safety standpoint, it may lack the
virtues of higher quality water of being clear, odorless, and tasteless. |
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sources
of fresh water
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Our
major source of fresh water comes from surface sources such as rivers and
lakes accounting for about 80% of the water used by people in the United
States. Underground sources contribute the remaining 20% of the water we
use. In America, especially in the eastern United States and other areas
where adequate rainfall occurs, we tend to take for granted an abundance
of good fresh water. |
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Treatment
makes water safe.
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Technology,
in the form of water treatment facilities, has largely made potable water
just another commodity we have available on demand. Just turn on a faucet
and there it is… in seemingly any quantity we want. It's good. It's cheap.
It's always available. Typically water is treated in a variety of ways
at municipal water treatment plants before humans are permitted to use
it.
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Treatment
varies depending on initial water quality.
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Contaminants
may be removed and other chemicals may be added. Bacteria are killed.
The particular treatment depends largely on the quality of the water source.
If the water is relatively pure to begin with, its treatment is minimal
and the cost of providing potable water is modest. On the other hand,
if the water source suffers from high levels of contaminants, treatment
can be more involved and more costly.
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Fresh
water is not limitless.
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Although
water seems like it might be limitless, it's not. As our population grows
and we find more and more uses for water, we've come to realize that water
is much more precious and limited than our casual thinking might suggest.
As we become more environmentally conscious, we appreciate the need to protect
our environmental sources of water from becoming overexploited and damaged
by pollution. In areas where the demand for fresh water exceeds the supply,
hard decisions regarding the rationing of the resource are required which
wind up making many people very unhappy. As the overall demand for fresh
water increases, expect to see many more instances of unhappy people who
aren't able to obtain water in the quantities they desire. |
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Converting
salt water to freshwater is usually prohibitively expensive.
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In
coastal regions, virtually unlimited ocean or sea water is available. Unfortunately,
this water is saline, meaning that it contains a great deal of compounds
known as salts. Common table salt (sodium chloride or NaCl) is an example
of a salt present in sea water. If you've ever tasted sea water, you have
an idea how extremely salty it is. You cannot safely drink sea water; it
is not fit for human consumption. Furthermore, treating sea water to remove
the salts to make it potable is extremely expensive. Only in extreme cases
where no other source of water is available are desalination plants built
to remove salt from sea water to produce potable water. Improvements in
technology may someday make desalination less expensive. |
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Good
quality water has many uses.
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Although
providing adequate supplies of potable water for human consumption is extremely
important, good quality water is equally important in other ways. Living
things, in general, depend on water for survival. Many plants and animals
can only thrive when clean, unpolluted water is part of their environment.
Agriculture falls in this category. So does much wildlife. Many industries
need large quantities of good quality water. Many recreational activities
are desirable only with good, clean water. |
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In
short, a good healthy environment is dependent on plentiful good, clean
water. It is in each of our best interests to each do our part in protecting
our water resources. |
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