COMMON WATER PROBLEMS
HARDNESS - Calcium (Ca) and Magnesium (Mg)
The term hardness refers to the quantity of dissolved
calcium and magnesium in water. These minerals, which come
primarily from limestone type rock formations, are found to
some degree in almost all natural waters. Calcium and
magnesium cause problems for two principal reasons:
When the water is warmed, they precipitate out of solution
and form a hard, rock-like scale. This scale accelerates
corrosion, restricts flow, and reduces heat transfer in
water heaters and boilers.
When they combine with soap, they react to form a curd,
which interferes with cleaning, dries out skin, and leaves
deposits on plumbing and clothes (bathtub ring; ring around
Hardness is measured in parts per million (or the equivalent
mg/L) or in grains per gallon (gpg). Note: if the water
analysis is given in ppm as CaCO3 then 1 gpg = 17.1 ppm. A
common aspirin tablet weighs 5 grains). There is no
established limit for the acceptable level of hardness in
water, but is generally considered to become problematic at
around 3 gpg.
Levels of hardness are referred to as follows:
||0 - 1
grains per gallon (gpg)
Slightly Hard Water
3.5 grains per gallon (gpg)
Moderately Hard Water
7 grains per gallon (gpg)
10.5 grains per gallon (gpg)
10.5 grains per gallon (gpg)
Waters which naturally
contain very little hardness can also be problematic because
they may be corrosive in some applications (see acidity).
The only practical method for hardness removal above 15 gpg
in residential applications is through cation exchange
process employed by water softeners.
Water which contains excess acidity tends to act
aggressively towards plumbing and fixtures, causing
corrosion and staining (ie. blue-green stains on fixtures
from copper pipes). Relative acidity/alkalinity is measured
on the pH scale, raging from 0 - 1.4, where 7 is neutral,
numbers lower than 7 are progressively more acidic, and
numbers higher than seven are increasingly alkaline (basic).
The pH value refers not to the quantity of acidity, but
rather to the relative acidity/alkalinity of a particular
Alkalinity acts as a buffer to deactivate the acidity, a
process called neutralization. For example, limestone
(calcium carbonate) is often applied to soil to offset the
acidity which comes from acid rain and decaying organic
material. The accepatable range for water is 6.5 - 8.5.
Acidity cannot be removed from water. However, it can be
neutralized by raising the pH with alkalinity. This can be
done by injecting a highly basic (alkaline) solution with a
feed pump or by passing the water through a bed of processed
limestone or similar material.
The presence of Iron is a very common water quality problem,
particularly in water from deep wells. Water containing even
a significant quantity of iron may appear clear when drawn,
but will rapidly turn red upon exposure to air. This process
is called oxidation, and involves the conversion of ferrous
(dissolved) iron, which is highly soluble, to ferric
(precipitated) iron, which is largely insoluble. The ferric
iron then causes red/brown staining of clothes, fixtures,
Iron concentration is measured in ppm or mg/l (milligrams
per liter, where 1 ppm = 1mg/l). Staining usually becomes a
problem at concentrations greater than 0.3 ppm. Removal is
through ion exchange (water softener) or
Hydrogen Sulfide (H2S)
Hydrogen Sulfide is a gas which smells strongly like rotten
eggs. It results from the decay of organic matter with
organic sulfur and the presence of certain types of
bacteria. Even very low concentrations are offensive as well
as highly corrosive (silver tarnishes almost immediately
upon contact with H2S).
Because it is in a gaseous form, H2S cannot be collected in
a sample bottle for laboratory analysis. Therefore, its
presence must be reported when a sample is submitted for
treatment recommendation. Depending upon the test results,
it can be removed by oxidation/filtration, aeration, or well
Turbidity is a measure of suspended particles in water and
can range from large particles which settle out of solution
rapidly (such as sand), to extremely fine sediment which may
stay suspended in solution even after standing for hours.
Treatment depends upon size, which is measured in microns.
Tastes and Odors
Most tastes and odors are caused by the presence of organic
matter and chlorine. The vast majority of these can be
removed with activated carbon.
Total Dissolved Solids (TDS)
TDS is the sum of the mineral salts in water and if too high
can result in objectionable taste, cloudy ice, interference
with the flavor of foods and beverages and scale left behind
in cookware. Generally speaking, the lower the TDS the more
acceptable the drinking water. TDS of 1,000 ppm or more is
unacceptable for drinking water. Reverse Osmosis (RO)
process has proven itself as the most practical and cost
effective method of correcting problems caused by high TDS.