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Aesthetic Water Quality
Problems
"Aesthetic water problems
have easily applied and proven solutions. Don't settle for unappealing
water."
There are several things in life that we take
for granted. Water is very often one of them. Each of us uses this vital
liquid, the most common substance on earth, everyday. And we rarely think
twice about it.
However, the water we use for cooking, drinking,
and countless other domestic tasks will quickly catch our attention when
there is some sort of problem.
Fortunately, some of the most obvious water
problems are also the easiest to solve. The problems
in this report are aesthetic. Although they are not considered harmful
to health, they do affect the look and taste of the water, and may cause
it to be undrinkable by some people's standards. Addressing these water
quality problems is therefore important. Issues such as taste
and odor,
color, and turbidity (cloudiness)
are all aesthetic water problems, and all have relatively simple solutions.
This report will discuss each of these problems in turn, EPA standards
regarding aesthetic problems, and finally present treatment
technologies to solve them.
In order to treat these problems, we must
first look at their source. Water is known as the universal solvent.
Before it reaches a consumer's tap, it comes into contact with many different
substances, such as gases, minerals, and organic matter. Water picks up
traces of these substances, and unfortunately, some of them may cause taste,
odor, color, or turbidity problems for the consumer.
Turbidity: Cloudy Water
At one time or another, most consumers have encountered
water that appears cloudy or foggy. This characteristic is due to turbidity:
the presence of finely divided solid particles in water. These particles
may be inorganic mineral matter which does not dissolve, or organic matter
that has been picked up as the water flows over and through the ground.
The particles cause the scattering and absorption of light rays, which
gives the water a cloudy appearance.
Whether turbidity is due to suspended organic
or inorganic matter, it can cause staining of sinks and fixtures, and the
discoloration of laundered fabrics. Inorganic turbidity can have an abrasive
effect on plumbing systems and may cause physical wear or erosion on pipes
and fittings. Turbidity is most commonly found at taps whose source is
surface water from lakes, streams, or ponds.
Taste and Odor
Another set of problems that will quickly catch
a consumer's attention is objectionable tastes or odors present in water.
These two senses appear to work in unison, which makes it difficult to
separate taste and odor.
A common characteristic of water from public
systems is the chlorine taste and odor, which is often quite noticeable.
Many public water systems treat water with chlorine to disinfect it. Although
this is an important step in the treatment of water because it destroys
disease-producing bacteria and other harmful organisms that may be in present
in water, there is no doubt that excess chlorine from the disinfection
treatment step can make the water objectionable.
In other cases, water with a high mineral
concentration may have an unpleasant soda or salty taste, and a metallic
taste may be produced by the presence of iron or manganese in water.
Many people have also encountered water that
contains hydrogen sulfide gas, which creates an objectionable odor. So-called
"sulfur water" not only produces the obnoxious "rotten egg" odor, but is
also corrosive to plumbing and can cause the rapid tarnishing of silver.
Even very low concentrations of hydrogen sulfide are detectable because
of the strong odor.
Various taste and odor conditions are caused
by the presence of organic matter in water. Even when the amount of organic
matter is very low, unusual tastes and odors such as musty, fishy, or earthy
smells may be found.
It is important to note that tastes and odors
affect drinking water as well as the foods and beverages prepared with
the water.
Color
Another very noticeable water problem is unusual
color, which can make the water unappealing to drink, and may cause the
staining of surfaces and materials touched by the water.
In some home water supplies, a yellowish coloration
may be present. This color condition is organic in nature, but presents
no health hazard. It is caused by the presence of microscopic suspended
particles.
This coloration occurs in regions where the
water passes through marshlands and has percolated down through peaty soils.
It is most likely to be found in the Southeast, Northwest, New England
and Great Lakes regions of the United States; and is more common in surface
water supplies and shallow wells than in deep wells.
Humic acids, often referred to as tannins,
are the real cause of the color condition. Often the color is not highly
visible in a glass of water, but can frequently be noticed when water is
drawn for a bath. The white porcelain background of the tub can highlight
even the slightest discoloration.
A more severe color condition may be caused
by the presence of iron in the water. Depending on the type and state of
the iron, the water may or may not be clear when it is first drawn. Water
with dissolved iron may appear clear when it is first drawn, but may turn
a brown-red color when it stands exposed to air or when it is heated. Water
with precipitated iron may have a reddish color or red particles when it
is first drawn.
The disadvantages of water containing significant
amounts of iron are obvious. It can leave brown-red stains on fixtures
and dishes, as well as discolor laundry. It is also unappealing for drinking.
Standards
The U.S. Environmental Protection Agency (EPA)
sets federal guidelines for contaminants that may adversely affect the
aesthetic quality of drinking water. These Secondary Maximum Contaminant
Levels (SMCL's) apply to any contaminant in drinking water which may adversely
affect the odor or appearance of the water, and consequently may cause
people to discontinue its use in favor of another supply, or otherwise
adversely affect "public welfare."
SMCL's differ from national primary (health
related) maximum contaminant levels (MCL's) in that they are not federally
enforceable. Instead, the SMCL's offer guidance to water quality based
on odor, aesthetics, or appearance; the primary MCL's are established by
the EPA based upon potential adverse health effects.
Treatment
If the water in a consumer's home has these problems
with turbidity, taste, odor, or color, what can be done? Fortunately, there
are several products available that can be directly installed in the home
to treat these problems. Point-of-Use (POU) and Point-of-Entry (POE) technologies
can treat water in the home and reduce these problems.
A process that is effective in reducing most
of these aesthetic problems is the use of an activated carbon filter.
These filters are specially designed for the removal of solid particles
from the water. Activated carbon is a unique material known for its ability
to adsorb (bind to its surface) soluble organic compounds and certain gases.
This quality makes it specially suited for use in water treatment and allows
it to act as a fine screen which traps solid particles, but allows the
water to pass through. Activated carbon filters are available in three
forms: solid block, precoat, and granular.
Carbon filters may either attach directly
to the faucet, or may be installed under the sink; filters for the whole
house may also be used to treat staining and odor problems.
Most taste and odor problems can be reduced
with the use of an activated carbon filter. To combat the taste and odor
problem of excess amounts of chlorine, for example, many consumers install
a filter at the kitchen tap. The filter adsorbs the excess chlorine, and
produces a tasty, clean water for cooking and drinking.
Turbidity may also be removed with an activated
carbon filter, or a particulate filter. The particulate filter will
trap the fine particles that cause a cloudy appearance, and its use will
result in a clear, clean appearance.
The problem of hydrogen sulfide in water is
more complex than many other odor problems. If the concentration of hydrogen
sulfide is very low, then an activated carbon filter may be used. For greater
concentrations, an iron removal filter should be effective in correcting
the problem. For high concentrations of hydrogen sulfide, a chlorination
system with activated carbon filtration would likely be the best solution.
Chlorine is potentially harmful, and must be handled carefully. Consult
a professional.
(RO)
Another treatment technique commonly used
in the home is a process called reverse osmosis (RO). In this process,
the water to be treated is forced against a semipermeable membrane, which
rejects contaminants suspended in the water. The membrane permits the new
water to pass to a holding tank where it is then available for use. RO
is effective in treating water that has a metallic taste, as well as reducing
numerous other health contaminants. It is also often paired with an activated
carbon filter.
Distillation is also often used for water
treatment. A distillation system raises the water temperature to
boiling. The water turns to vapor, leaving behind contaminants that have
been dissolved in it, as well as microscopic solids, microorganisms, and
organic materials. The clean water vapor enters a condenser where it is
cooled, and returned to its liquid state. This process produces a clean,
clear water with a distinctive clarity.
To treat water that is colored as a result
of humic acids, an anion exchange resin may be used. The resin adsorbs
the the organic bodies that cause the discoloration, and will leave behind
clear water.
For color problems that are due to low or
moderate levels of dissolved iron, a household water softener may
remove the impurity. The soluble iron is removed from the water by ion
exchange, in the same way that hardness is removed by a water softener.
If much of the iron is already precipitated,
or the iron concentration is too high for a water softener, an iron
removal filter should be used. The filter forms a barrier that prevents
the continued passage in the water.
Whether a water problem involves turbidity,
taste, odor, or color, the first step to its treatment is to have the water
tested. Testing determines the precise cause of the problem so the ideal
treatment may be applied.
When the safety of the water is in question,
it should be tested by a state certified, EPA certified, or other reputable
laboratory. Testing for turbidity, taste, odor, or color problems may be
performed in the home by a professional water treatment dealer.
Before purchasing a product, become an educated
consumer. Determine what water problems the proposed product reduces, and
to what level. Check the product's performance capabilities, maintenance
provisions, and warranty.
Aesthetic water
problems have easily applied and proven solutions. Don't settle for unappealing
water.
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