• TABLE OF CONTENTS
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 Historic note
 Front Cover
 Table of Contents
 Main














Group Title: Circular - University of Florida Institute of Food and Agricultural Sciences ; 703
Title: Home water quality and safety
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00067073/00001
 Material Information
Title: Home water quality and safety
Series Title: Circular Florida Cooperative Extension Service
Physical Description: 12 p. : ill. ; 28 cm.
Language: English
Creator: Haman, Dorota Z
Bottcher, Adelbert Brace, 1949-
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville
Publication Date: 1986
 Subjects
Subject: Drinking water -- Contamination   ( lcsh )
Drinking water -- Contamination -- Florida   ( lcsh )
Drinking water -- Purification   ( lcsh )
Water quality -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 12.
Statement of Responsibility: Dorota Z. Haman and Del B. Bottcher.
General Note: Cover title.
General Note: "May 1986."
Funding: Circular (Florida Cooperative Extension Service) ;
 Record Information
Bibliographic ID: UF00067073
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 15235549

Table of Contents
    Historic note
        Historic note
    Front Cover
        Front cover
    Table of Contents
        Table of Contents
    Main
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
Full Text





HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida





bOCUITEXI'


Home Water Quality

and Safety
Dorota Z. Haman and Del B. Bottcher


r I HUME LIBRARY


DEC 11 1986


I.F.A.S. Univ. of Florida


Florida Cooperative Extension Service/Institute of Food and Agricultural Sciences/University of Florida/John T. Woeste, Dean


II I


Circular 703


4


May 1986


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Table of Contents
Introduction .......................................... .... ... ... ... ..... ...... ...... 1
Effect of Water Quality on Human Health .................. ......................... 1
Bacterial Contam nation ................ ............. ................... .. ................. 2
Nuisance Contamination
Water Hardness ............................. ....................... ... ........... 2
Iron and Manganese ............................................ ...................... 2
Turbidity ......................... ... .................... ................ .... 3
Color, Odor, and Taste ....................................... ........................ 3
Corrosion ..................................... ................................... 3
Metal Contamination
Metals and Their Importance to Organic Life ..... ....... ......................... ....... 3
Metals in a Water Supply and Their Toxic Effects ............................................ 4
Other Contamination
Chlorides ............ .... ..... ... ............................ 5
Fluorides .......................... ... .............................. 5
Nitrates .......... ..................... ....................... .............. 5
Organic Compounds ............... ................. ...... ........... ........... 5
Radionuclides ..................................... ... .......... ............. 6
Total Dissolved Solids ............ ............ .......... .......... ............. 6
Sulfates ............................................... ................ 6
Having the Water Tested
Testing for Individuals .......................... ..... ........................ ............ .. 6
Units of Measure Used to Express Test Results ..................... ....................... 6
Methods of Analysis for Mineral Content .............................................. 7
Methods for the Control and Elimination of Water Problems
Disinfection ................. .......................................... 7
Activated Carbon Filters .......................................................... 8
Reverse Osmosis ................................................................... 9
Water Softening ......................................... ........................ 9
Aeration and Other Methods for Removal of Dissolved Gases ..................................... 10
Coagulation, Flocculation, Sedimentation, and Filtration ......................................... 10
Iron and Manganese Removal ................................. .................... 10
Nitrate and Nitrite Control ............. ... ....... ......................................... 1
Volatile Organic Halide Removal .. . ............................................ 11
Trace Metal Removal ........................................ ............................ 11
Corrosion Control in Household Systems ................ ..................................... 11
Sum m ary ................ ................. ... .. ... ....... .. ..... .. .. ........... 11
References .................................................................... 12








Home Water Quality and Safety

Dorota Z. Haman and Del B. Bottcher*


Introduction
Water, an absolute essential for life on earth, is the
most widely distributed nongaseous substance in nature.
Because of water's importance, the pattern of human
settlement throughout history has often been deter-
mined by its availability. Fertile river valleys with abun-
dant water supplies were the centers for beginning civili-
zations; with growth, demand for water has increased
dramatically and its uses have become much more
varied. Per capital use in the U.S. is nearly 200 gallons
per day. This includes water used in agriculture, indus-
try, recreation, and noningested personal consumption.
Frequently, each of these uses requires a different level
of quality in order for the water to be considered
adequate.
Good quality drinking water may be consumed in any
desired amount without adverse effect on health. Such
water is called "potable." It is free from harmful levels
of impurities: bacteria, viruses, minerals, and organic
substances. It is also aesthetically acceptable, is free
of unpleasant impurities, such as objectionable taste,
color, and turbidity, and is free of odor.
Florida has plentiful sources of fresh water (usually
ground water) throughout most of the state. However,
some of this water has quality problems. Fortunately,
most can be corrected using proper equipment and
methods. The most common problems in household
water supplies may be attributed to hardness, iron, iron
bacteria, sulfides (sulfur), sodium chloride (salt), acidity
(low pH), and disease-producing pathogens, such as
bacteria and viruses. With intensive agriculture, the
leaching of nutrients and pesticides into the water supply
may cause additional problems. There is also a growing
concern of pollution caused by the leaching of industrial
wastes into the aquifers.
Properly located and constructed wells are usually the
best sources of water for domestic use. Such water is less
likely to be contaminated than water from surface
sources. Surface water from streams, lakes, and ponds is
almost always contaminated and requires proper treat-
ment for domestic use. The treatment of surface water
for human consumption is usually difficult and can be
very costly. However, the content of dissolved minerals
such as iron, manganese, and calcium is likely to be
much lower than in well water.
In view of the possible quality problems, a new water
supply should always be tested before use and old
sources should be periodically checked for changes.
Well water would not be expected to change rapidly,
so frequent monitoring would not be necessary. The
county health department is equipped to test for bac-


trial contamination. It determines whether the water is
safe for human consumption at the time of the test.
Periodic bacteriological tests are desirable thereafter. A
second test should be performed for mineral content in
order to classify other possible problems and to select
the methods and materials necessary for their correc-
tion.
The level of testing required by Florida law (Adm.
Code 17-22, Florida Department of Environmental
Regulations, FDER) varies according to the number of
persons supplied by the water system. An individual
water supply which serves only one household only re-
quires a bacterial test at time of installation. However, a
community water system which is a public water system
serving at least 15 year-round residents much be periodi-
cally tested. Because of this additional testing, commu-
nity supplies tend to be safer than individual systems.
The larger the number of people the greater the precau-
tions.
In fact, every system in Florida serving more than
1000 persons must be tested for a more extensive list of
contaminants, including volatile organic, effective June
1, 1985. Starting January 1, 1987 all community water
supplies will be required to increase their testing fre-
quency.


Effect of Water Quality on Human Health
The effect of toxic contaminants on human health can
be classified as either acute or chronic. The reaction to a
substance causing serious illness or death in an indi-
vidual within 48 hours after exposure is considered acute
toxicity. Chronic toxicity is a longer term effect on
health due to frequent exposure to small amounts of a
toxic substance. Chronic reactions to chemicals are dif-
ficult to study and our knowledge of the chronic toxic
effects of nearly all chemicals is very poor. Examples of
chronic health effects would be kidney and liver disease,
cancer, mental illness, etc.
Based on epidemiological evidence and experimenta-
tion on laboratory animals, the U.S. Public Health Ser-
vice has established maximum contaminant levels
(MCL) allowable in drinking water. Most of these levels
allow a sufficient margin of safety; however, one must
remember that acceptable contaminant levels vary
widely among individuals and population groups. For
example, high sodium, which may be harmless for many
people, can be dangerous for the elderly, hypertensives,
pregnant women, and people having difficulty in excret-
ing sodium. Specific symptoms of different contami-
nants are presented in more detail in later sections.


*Assistant and Associate Professors, respectively, Department of Agricultural Engineering, University of Florida, Gainesville, FL 32611.









Bacterial Contamination


The only required and routine test to be conducted on
drinking water from a private well is that for sanitation.
The main indicator of the sanitary quality of drinking
water is the coliform bacteria count (MCL = average of
1 or fewer per 100 ml). A high count of these bacteria is
an indication of contamination from a septic system or
other fecal pollution source. The presence of coliform
bacteria, which can be found in the feces of humans and
animals, indicates that there is a high probability of
other pathogenic organisms (disease germs) present.
When water is contaminated with a surface drainage,
noncoliform bacteria may also be present in large num-
bers. This type of contamination may not be harmful
since there is only a small probability that drainage
water contains pathogenic organisms. However, if the
count of noncoliform bacteria is more than 200 per
100 ml, water is also considered to be poor quality.
With recent improvements in the water supply in the
U.S., the transmission of illnesses by drinking water has
been infrequent. In Florida, only two cases related to
home water wells were recorded in 1984.
Superchlorination followed by dechlorination is the
most common solution for potential bacteria in the wa-
ter supply. Mineral and chemical problems found in an
individual home water supply are usually a more com-
mon concern than bacteria and often require other treat-
ment.

Nuisance Contamination
Water Hardness
Hardness is defined as the concentrations of calcium
and magnesium ions expressed in terms of calcium car-
bonate, which can be calculated by the following equa-
tion:
Hardness (mg/l) = 2.5 x conc. of Ca2+ (mg/l)
+ 4.1 x cone. of Mg2 (mg/1)
The most frequently used standard classifies water sup-
plies as follows:


Hardness Concentration
Soft water 0 to 1 grain/gallon (0-17.1 mg/l)
Slightly hard 1 to 3.5 grains/gallon (17.1-51.3 mg/1)
water
Moderately 3.5 to 7 grains/gallon (51.3-119.7 mg/l)
hard water
Hard water 7 to 10.5 grains/gallon (119.7-
179.55 mg/l)
Very hard Over 10.5 grains/gallon (over
water 179.55 mg/l)


These minerals in water can cause some everyday prob-
lems. They react with soap and produce a deposit called
"soap curd" that remains on the skin and clothes and,
because it is insoluble and sticky, cannot be removed by
rinsing. Soap curd changes the pH of the skin and may
cause infection and irritation. It also remains on the hair
making it dull and difficult to manage. Soap curd picks
up the dirt from laundry water and holds it on cloth,
contributing to a gray appearance of white clothes. It is
especially troublesome when wash water is allowed to
drain through the clothes. The use of synthetic deter-
gents may help a little, but the active ingredient in the
detergent is partially inactivated by hardness and more
detergent must be used for the same cleaning task. Some
detergents will produce soap during the reaction with oil
or grease on the surface being cleaned and as a result
they will also deposit soap curd. A ring around the
bathtub and spotting on glassware, chrome, and sinks
are constant problems in the presence of hard water.
They require additional rinsing and wiping, increasing
the time spent on everyday cleaning.
Cooking with hard water can also be difficult, produc-
ing scale on pots. Some vegetables cooked in hard water
lose color and flavor. Beans and peas become tough and
shriveled.
Hard water may also shorten the life of plumbing and
water heaters. When water containing calcium carbon-
ate is heated, a hard scale is formed that can plug pipes
and coat heating elements. Scale is also a poor heat
conductor. With increased deposits on the unit, heat is
not transmitted to the water fast enough and overheat-
ing of the metal causes failure. Build-up of deposits will
also reduce the efficiency of the heating unit, increasing
the cost of fuel.
Most natural water supplies contain at least some
hardness due to dissolved calcium and magnesium salts.
Other minerals, such as iron, may contribute to the
hardness of water, but in natural water, they are gener-
ally present in insignificant quantities. The total hard-
ness of water may range from trace amounts to hundreds
of milligrams per liter.
Iron and Manganese
The presence of iron and manganese in large quanti-
ties is very easy to notice because of the reddish brown
stain these minerals cause. The stain shows on laundry,
sinks, and every other object touched by water. Iron is
transported by water in a ferrous state forming a clear,
colorless solution until it comes into contact with ox-
ygen. Oxygen changes iron to the ferric state which
reacts with alkalinity in the water and forms an insoluble
brown ferric hydroxide precipitate called "yellow boy."
Iron and manganese occur naturally in ground water,
but some iron can be added to the water from corroded
pipes.









Iron and manganese in combination with natural or
man-made organic compounds will cause even more
staining problems. Organic compounds react with iron
and manganese to form very stable and difficult to re-
move darkly colored materials.
In addition to staining problems, large amounts of
these metals can influence the taste of water and cause
the development of iron and manganese bacteria, which
are not a health hazard but are very unpleasant. They
form masses of gelatinous and filamentous organic mat-
ter that traps the iron and manganese they use for
growth. A good indication of their presence in the sys-
tem is a brown slimy growth in the toilet flush tank.

Turbidity
Solid particles suspended in water absorb or reflect
light and cause the water to appear "cloudy." These
particles are undissolved inorganic minerals or organic
matter picked up over or under the ground. Since the
surface of the earth acts as an excellent filter, the water
from deep wells is usually clear without significant
amounts of turbidity. This problem is more common in
the water from surface supplies.
The major problem with turbidity is aesthetics, but in
some cases suspended matter can carry pathogens with
it. Large amounts of organic matter can also produce
stains on sinks, fixtures, and laundry. Much like iron,
organic matter in water may also produce colors, un-
pleasant tastes, and odors. These tastes and odors will
affect not only drinking water, but the foods and bever-
ages prepared with the water.

Color, Odor, and Taste
It was already mentioned that iron and manganese
will produce reddish brown stains. However, the color
in water is most often caused by dissolved matter from
decaying organic materials. Some color is almost always
present in surface water, but it can occur in well water
also.
Color makes water unpleasant for drinking and cook-
ing and, like iron and manganese, causes staining. Or-
ganic matter very often contributes to tastes and odors.
Even very small amounts of it can result in a musty odor
and an "off" taste. A major cause of taste and odor
problems is metabolites produced by actinomycetes,
algae, or other microorganisms.
If water has a distinctive "rotten egg" odor, hydrogen
sulfide gas is present in the water supply. Even very low
concentrations will result in strong obnoxious odors. In
addition to this, the water rapidly tarnishes silver and is
corrosive to plumbing metals.
For a pleasant taste, water should have some dis-
solved minerals. Distilled water without minerals tastes
"flat." However, high concentrations of minerals make
water taste salty or metallic, and the taste can easily be


detected in foods and beverages prepared with highly
mineralized water. The presence of dissolved oxygen
can improve taste. Faucet aerators will put oxygen in the
water and can help remove obnoxious gases.

Corrosion
Corrosion is a natural process involving chemical/
electrical degradation of metals in contact with water.
The rate of corrosion will vary depending on the acidity
of the water, its electrical conductivity, oxygen concen-
tration, and temperature. Acidic water with pH values
in the range of 6 to 7 is more corrosive to the metals used
in plumbing systems than alkaline water. Both ground
and surface water can be acidic.
Common causes for acidic surface water are acid rain-
fall due to atmospheric carbon dioxide and other air-
borne pollutants, runoff from mining spoils, and decom-
position of plant materials. Acidic ground water can also
be caused by the above factors but is mostly controlled
naturally by the equilibrium relationship with surround-
ing minerals. For example, most ground water in Florida
is alkaline with pH in the range of 7 to 10 because of the
geological formation of the aquifer, which is composed
of calcium carbonate (limestone).
Alkaline water does not eliminate corrosion if it has
high electrical conductivity. When two different metals
such as steel and brass are in contact with a solution
which will conduct electricity, a galvanic cell is estab-
lished. One of the metals will corrode in proportion to
the electricity generated. If plumbing is installed using
different metals (copper, steel, brass, zinc, and various
alloys) corrosion will occur.
Oxygen dissolved in water will also enhance the pro-
cess of corrosion. Deep well water is usually free of
dissolved oxygen, but it is present in surface water. The
temperature of water is a significant factor in the rate of
corrosion. Above 140F the rate of corrosion of steel
doubles with every 20F increase in temperature.


Metal Contamination
Metals and Their Importance to Organic Life
Several metal ions such as sodium, potassium, magne-
sium, and calcium are essential to sustain biological life.
At least six additional metals, chiefly transition metals,
are also essential for optimal growth, development, and
reproduction, i.e. manganese, iron, cobalt, copper,
zinc, and molybdenum.
An element which is required in amounts smaller than
0.01% of the mass of the organism is called a trace
element. The table on the next page shows that the
average person weighing 154 lbs (70 kg) requires the
following amounts of metals in the body to maintain
good health:









Major Metal Ions
Sodium (Na)
Magnesium (Mg)
Potassium (K)
Calcium (Ca)
Trace Metals
Manganese (Mn)
Iron (Fe)
Cobalt (Co)
Copper (Cu)
Zinc (Zn)
Molybdenum (Mo)


grams
70
40
250
1700

0.03
7
0.001
0.150
3
0.005


Only the last six ions are in small enough quantities to be
considered trace elements. Trace metals function mostly
as catalysts for enzymatic activity in human bodies.
However, all essential trace metals become toxic when
their concentration becomes excessive. Usually this
happens when the levels exceed by 40- to 200-fold those
required for correct nutritional response.
Drinking water containing the above trace metals in
very small quantities may actually reduce the possibility
of deficiencies of trace elements in the diet. However, in
some cases, if the metal is present in the water supply,
there is a danger of overdose and toxic effect.
In addition to the metals essential for human life,
water may contain toxic metals like mercury, lead, cad-
mium, chromium, silver, selenium, aluminum, arsenic,
and barium. These metals can cause chronic or acute
poisoning and should be eliminated from the drinking
water if possible.

Metals in a Water Supply and Their Toxic Effects
The reader is cautioned not to be overly concerned
about the symptoms and toxic reactions presented here
because it is extremely rare for concentrations of these
metals in Florida drinking water to exceed the standards
presented. Also, many of these metals would cause a
change in water taste before dangerous levels are
reached. However, if industrial contamination is sus-
pected, then more concern is in order.
Aluminum (no MCL established; 0.2 mg/l considered a
safe maximum). High aluminum levels are associated
with premature senile dementia (Alzheimer's dis-
ease) and two other types of dementia as well.
Arsenic (MCL = 0.05 mg/l). Minor symptoms of
chronic arsenic poisoning are similar to those of many
common ailments, making actual arsenic poisoning
difficult to diagnose. This type of poisoning can make
people tired, lethargic, and depressed. Other symp-
toms are white lines across the toenails and finger-
nails, weight loss, nausea and diarrhea alternating
with constipation, and loss of hair. Arsenic is highly
toxic and unfortunately widespread in the environ-


ment due to its natural occurrence and former exten-
sive use in pesticides.
Barium (MCL = 1.0 mg/1). Since there are few data on
the chronic effects of barium, the MCL includes a
large safety factor. High levels of barium can have
severe toxic effects on the heart, blood vessels, and
nerves. It is capable of causing nerve blocks at high
doses. 550 to 600 mg is a fatal dose for humans.
Cadmium (MCL = 0.01 mg/l). Acute cadmium poison-
ing symptoms are similar to those of food poisoning.
Up to 325 mg of cadmium is not fatal but toxic symp-
toms occur at 10 mg. It is associated with kidney 0
disease and linked to hypertension. There is also some
evidence that cadmium can cause mutations.
Calcium (MCL not established). Low calcium intake
can be related to hypertension and cardiovascular
disorders. There is a link between low calcium intake
and osteoporosis. With a low level of calcium in the
diet, drinking water may provide a significant portion
of the daily calcium requirement.
Chromium (MCL = 0.05 mg/1). It has been shown that
freshwater and saltwater aquatic life can be adversely
affected by the presence of chromium. The effect of
chromium in drinking water has not been thoroughly
investigated. However, chromium is known to pro-
duce lung tumors when inhaled.
Copper (MCL = 1 mg/1). Studies show that U.S. diets
are often deficient in copper. Its deficiency causes
anemia, loss of hair pigment, growth inhibition, and
loss of arterial elasticity. High levels of vitamin C
inhibit good copper absorption. However, water con-
taining amounts higher than 1 mg/1 is likely to supply
too much of this metal. One milligram per liter is also
a taste threshold for the majority of people. Copper is
highly toxic and very dangerous to infants and to
people with certain metabolic disorders. Uptake of
copper is also influenced by zinc, silver, cadmium, and
sulfate in the diet.
Iron (MCL = 0.3 mg/l). The presence of iron in drink-
ing water may increase the hazard of pathogenic
organisms, since most of these organisms need iron to
grow. The bioavailability of iron in drinking water has
not been well researched. It is known that iron in-
fluences the uptake of copper and lead.

Lead (MCL = 0.05 mg/1). Lead can occur naturally, or
result from industrial contamination, or be leached
from lead pipes in some water systems. If the plumb-
ing contains lead, higher levels will be detectable in
the morning after water has been standing in pipes
throughout the night. Lead is a cumulative poison.
Lead poisoning is difficult to distinguish in its early
stages from minor illness. Early reversible symptoms









include abdominal pains, decreased appetite, con-
stipation, fatigue, sleep disturbance, and decreased
physical fitness. Long term exposure to lead may
cause kidney damage, anemia, and nerve damage
including brain damage and finally death.
Magnesium (MCL not established). An average adult
ingests as much as 480 mg of magnesium daily. Any
excess amounts are quickly expelled by the body. No
upper limit has been set for this metal in drinking
water. It can, however, create a problem for people
with kidney disease. They may develop toxic reac-
tions to high levels of magnesium, including muscle
weakness, coma, hypertension, and confusion.
Manganese (MCL = 0.05 mg/l). Excess manganese in a
diet prevents the use of iron in the regeneration of
blood hemoglobin. Large doses of manganese cause
apathy, irritability, headaches, insomnia, and weak-
ness of the legs. Psychological symptoms may also
develop including impulsive acts, absent-mindedness,
hallucinations, aggressiveness, and unaccountable
laughter. Finally, a condition similar to Parkinson's
\disease may develop.
-,Mercury (MCL = 0.002 mg/1). Mercury poisoning
symptoms include weakness, loss of appetite, insom-
nia, indigestion, diarrhea, inflammation of the gums,
black lines on the gums, loosening of teeth, irritabil-
ity, loss of memory, and tremors of fingers, eyelids,
lips, and tongue. At higher levels, mercury produces
hallucinations, manic-depressive psychosis, gingivi-
tis, sialorrhea, increased irritability, muscular trem-
ors, and irreversible brain damage.
Selenium (MCL = 0.01 m/1). One recognized effect of
selenium poisoning is growth inhibition. There is
some evidence that selenium is related to skin discol-
oration, bad teeth, and some psychological and gas-
trointestinal problems. On the other hand, a small
amount of selenium has been found to be protective
against other heavy metals like mercury, cadmium,
silver, and thallium.
Silver (MCL = 0.05 mg/1). The'first evidence of excess
silver intake is a permanent blue-gray discoloration of
the skin, iucous membranes, and eyes. Large doses
of silver can be fatal.
Sodium (MCL = 160 mg/l). The fact that some patients
with heart disease have difficulty in excreting sodium
and are put on a low sodium diet has led to the idea
that sodium is bad for the heart. However, studies
show no correlation between sodium concentration
and cardiovascular disease mortality. On the con-
trary, beneficial correlations for sodium have been
reported. Areas where water is hard, highly mineral-
ized, and also high in sodium tend to have lower
cardiovascular death rates. This does not contradict


the fact that in some individuals the lowering of
sodium in a diet is effective in lowering the blood
pressure. Depending on age, general health, and sex,
sodium may present a problem in drinking water. If
the sodium in water exceeds 20 mg/l, it is advisable to
contact the family physician for an opinion.

Other Contamination
Chlorides (MCL = 250 mg/l). Chlorides are normally
associated with salty water. Sodium chloride is com-
mon table salt and also is the salt found in seawater.
High chloride levels can cause human illness and also
can affect plant growth at levels in excess of 1000 mg/1.
Taste threshold is about 250 mg/l for most people.
Fluorides (MCL = 1.4 to 2.4 mg/l, function of climate).
The optimum level of fluorides in water for reducing
dental cavities is about 1 mg/1. Higher levels could
cause mottling of the teeth. For the Florida climate
the MCL will be between 1.4 and 1.6 mg/l. Reduced
MCL values in a hot climate are justified by increased
daily intake of drinking water in warm weather. Con-
troversy over negative and positive effects of adding
even small amounts of fluorine to drinking water
make it very difficult to accurately summarize its
Effect on the human body.
itrates (MCL = 10 mg/1 as N). Nitrates are present in
water particularly in regions where agricultural fertil-
ization or organic waste disposal may be polluting
water sources. The nitrate level in drinking waters
extremely important with infants, because of their
high intake of water with respect to body weight.
Nitrates in the infant are converted by the body to
n---itrites that oxidize blood hemoglobin to methemo-
globin. The altered blood cells can no longer carry
oxygen, which can result in brain damage or suffoca-
tion. The upper limit for nitrates in drinking water is
10 mg/l as nitrogen. This is about 45 mg/1 of the nitrate
ion. Epidemiological studies show a correlation be-
tween high nitrate levels and gastric and stomach
cancers in humans.
Organic compounds (variable MCL). Organic com-
pounds include a wide range of substances, all of
which contain carbon. The common types of indus-
trial organic substances found in water are petroleum
products, solvents, pesticides, and halomethanes.
These are generally referred to as either hydrocar-
bons or organic halides (usually chlorinated hydrocar-
bons). Most organic halides, especially the man-made
compounds, have been found to be toxic-acutely at
high concentration and chronically at very low con-
centrations. These types of organic compounds run
from methylene chloride (CH2C12) to DDT (1,1,1-
trichloro-2,2-bis(p-chlorophenyl)ethane). Most vola-
tile (or purgeable) chlorinated organic chemicals can









cause cancer. High concentration symptoms include
nausea, dizziness, tremors, and blindness. Florida is
about to require testing for all 75 halogenated or-
ganics in community water systems. The testing
methods for these chemicals are very complex, expen-
sive, and time consuming. Usually gas chromatog-
raphy with mass spectroscopy and a computer search
involving expensive equipment and highly trained
operators are required. As a result, the average
homeowner cannot afford this complete test.
Radionuclides: radium-226 and radium-228 (MCL =
5 pCi/1); tritium (hydrogen-3, MCL = 20,000 pCi/1);
strontium-90 (MCL = 8 pCi/1). These doses are based
on not exceeding 4 millirem/year (rem stands for
roentgen-equivalent-man, a radiation dosage unit) of
net a, p, and photon radioactivity. Excessive levels
could cause radiation sickness or bone disease. The
presence of radium in drinking water is not of great
concern because it is not retained in the body.
Total dissolved solids (TDS, MCL = 500 mg/l). TDS
represent mostly the total mineral content of the wa-
ter (what's left after evaporation of a water sample),
primarily salts, carbonates, and metals. Organic com-
pounds may also be dissolved solids. A high concen-
tration of TDS is an indicator of possibly high volume
contamination and further investigation may be rec-
ommended.
Sulfates (MCL = 250 mg/1). Sulfates are associated
with gypsum formations and are common in several
areas of Florida. High sulfate water can cause di-
arrhea, and in fact was commercially sold as a laxative
in the past.

Having the Water Tested
Water Testing for Individuals
The only way to know what is in your water is to have
it tested. Generally the only required test for individual
supplies is that for bacteria contamination, conducted
by the local health department. Upon special request
and indicated need the local health department or the
Florida Department of Environmental Regulation can
run additional tests. If a homeowner is simply curious or
has personal concern, private testing sources will have to
be used. This testing may become quite expensive.
The first step for any test is getting a reliable, repre-
sentative sample. The need for careful sampling tech-
niques varies according to the constituent being tested,
i.e. bacteria and volatile organic are very sensitive to
sample collection procedure while hardness and salts are
fairly insensitive to sampling technique. Storage proce-
dures before analysis and time between sampling and
analysis are also very important but again vary substan-
tially for each substance.


A general procedure for taking a sample is given
below and would be sufficient for many problems includ-
ing bacteria. In any cases where there is doubt, the
laboratory performing the test should be contacted for
instructions and a sampling bottle. In fact, in some cases
the laboratory may want to take the sample. The follow-
ing procedures should be followed for general sampling:
1. The sampling bottle should be clean and sterile
with nothing except the water to be sampled com-
ing in contact with the inside or cap of the bottle.
2. A faucet without leaks around the handle should
be selected for sampling. It must be cleaned and
dried.
3. The water should run for an ample period of time
to ensure fresh water from the well before collect-
ing a sample. The water should not make contact
with any object before running into the bottle. The
sample should be capped immediately to preserve
volatile compounds in the water and prevent
atmospheric contamination.
4. The sample should be analyzed within 24 hours to
give accurate results. For best results, on-site test-
ing of water is suggested if possible.
In making a decision whether to test for organic com-
pounds, the following should be considered. First, are
there any industrial disposal sites, pesticide users,
machine shops, automotive garages, or other industries
close enough to contaminate the aquifer? Second, is
there any source of chlorine near the aquifer? Chlori-
nated water can have elevated organic halide levels,
commonly trihalomethanes (MCL = 0.1 mg/1). Re-
search is currently being conducted to modify the treat-
ment process to keep these substances from drinking
water. However, for now, chlorination must continue to
be used to kill infectious organisms in water.

Units of Measure Used to Express Test Results
Most analyses for contaminants provide results in
terms of concentration,, which are usually expressed in
units of either parts per million (ppm) or milligrams per
liter (mg/1). These two units are used interchangeably by
most persons, but are technically different. For the
range of concentrations found in most water supplies,
the difference is negligible. However, for uniformity in
reporting milligrams per liter is used. Concentrations
greater than 10,000 mg/1 are commonly expressed in
percentage by weight.
In the domestic water treatment industry, water hard-
ness is often reported in grains per gallon. One grain per
gallon is equal to 17.1 mg/1.
"Acidity" of water is expressed in pH units. It is the
logarithm of the reciprocal of the hydrogen ion concen-
tration [H ] in the solution. For pure water the hydro-
gen concentration is 1 x 10-7 moles per liter and the









solution can be characterized as pH 7. The pH can range
from 0 to 14, but most potable water will range from 6.5
to 8.5. Any solution with a pH below 7 is acidic; any
solution with a pH above 7 is alkaline.
If you have your water tested for a broad range of
substances, do not be surprised if a lot of things are
found and reported. Compare results with accepted
standards and nuisance levels discussed previously be-
fore becoming concerned. If a problem is found or con-
fusion as to the meaning of the results develops, then a
water quality treatment expert should be consulted.
Your local health department or Florida Department of
Environmental Regulation office should be notified if a
standard MCL is exceeded. These agencies as well as
private water treatment companies can be contacted for
specific treatment recommendations.

Methods of Analysis for Mineral Content
The most common techniques for analyzing water for
easily detected factors are colorimetric and titrametric
testing methods. Colorimetric testing methods are
based on matching color reactions with simulated color
standards that represent known values. Titrametric test-
ing methods are the procedures requiring the gradual
addition of an accurately standardized solution known
as a titrant to the test sample until a color change occurs.
Field test kits using these techniques are readily avail-
able for the detection of several minerals.
There are other analytical techniques used mostly for
analysis of trace elements and organic contaminants.


KITCHEN OR BATHROOM
COLD FAUCET
TASTE a ODOR
TANK FILTER
(USUALLY ACTIVATED
i \ 1 CARBON )


WATER AUTO
SOFTENER IRON
REMOVAL
TANK
FILTER


These include atomic absorption spectroscopy, acti-
vation analysis, chromatography, mass spectroscopy,
emission spectroscopy, and others. These techniques
are usually expensive and require sophisticated labora-
tory equipment. Specific analytical techniques are listed
in FDER Rules and Regulations (Adm. Code 17-21 and
17-22).

Methods for the Control and Elimination
of Water Problems
With properly installed and maintained treatment sys-
tems, most water can be made safe and pleasant to
drink. Treatment systems should be checked routinely
to detect possible problems. The following paragraphs
review specific methods of water treatment and what
they are used for. Before getting into the individual
treatment processes it will be important to know the
general order in which these treatment steps should
occur. Multiple treatments are common but if initiated
in the wrong sequence, one treatment may negate
another. Figure 1 shows this sequence for a very com-
plete system, all of whose parts will not be required in
most cases.

Disinfection
Disinfection is defined as an integrated system of
treatment processes that reliably reduces the population
of viable pathogenic microorganisms to levels deemed
to be safe by public health standards.



HARD WATER TO
OUTSIDE FAUCETS
REALIZINGG
; FILTER --CITY WATER SUPPLY

+OR

SLWELL WATER SUPPLY
I f' PRESSURE (LARGER IF ALSO
nf T TANK RESIDENCE TANK)
InrrMFMT PUMP


j FILTER IN
AUT (OPTIONAL WELL
AUTO LOCATION )
CLARIFYING LO ) WATER
TANK SOLUTION
FILTER DISPENSING SYSTEM
(SAND FILTER) (DISINFECTANT OR OXIDANT )


Figure 1. Order of Installation of water treatment equipment. Only sequence is shown; all items are seldom needed.








The use of chlorine and its compounds is the most
common disinfection method in private water supply
systems in the U.S. It is inexpensive, readily available in
several forms, and effective against bacteria. Its effec-
tiveness is easy to test by measuring the chlorine residue
in a system. However, in a small system the time be-
tween adding chlorine and using water is so short that
relatively high concentrations are required. Larger re-
tention tanks can increase contact time before use and
reduce required concentration. Research findings indi-
cate that carcinogenic and mutagenic halogenated or-
ganic compounds (halomethanes) can actually be
formed during chlorine disinfection when organic sub-
stances are present. With this discovery, activated car-
bon filtration or reverse osmosis units should become a
part of all up-to-date home chlorination systems.
Small amounts of water can be disinfected by boiling
for 15 minutes. However, the process is energy intensive
and may even increase the concentration of other con-
taminants due to evaporation.
There are other methods of water disinfection. Most
of them are still too complex or too expensive for home
water supply. They are discussed here for a few reasons.
These methods are effective and they are being con-
stantly improved. With the development of new tech-
nology they may quickly become a good, feasible solu-
tion for water disinfection in individual water supplies.
They include ultraviolet radiation, ozonation, iodina-
tion, and distillation.
Ultraviolet radiation, in order to be effective, must
pass through every particle of water. The water there-
fore cannot have any turbidity, suspended soil particles,
or organic matter. Ultraviolet radiation adds nothing to
the water and does not produce any taste or odor. It is
very effective on pathogens but not on protozoan cysts
such as those responsible for giardiasis. Because of the
possible presence of protozoan cysts, a 5-pjm filter must
be added to the system. Ultraviolet radiation disinfec-
tion also requires a safety system, where a photoelectric
cell activates an alarm system and/or stops the water
pump if the ultraviolet radiation intensity is not suf-
ficient for safe disinfection. The major problems with
such a system are cost, fouling of the chamber, collec-
tion of sediment, and growth of algae. In the latest
ultraviolet radiation systems, Teflon tubes are used in-
stead of quartz tubes and seem to decrease these prob-
lems.
Ozone is a very strong oxidizing gas and is very effec-
tive in killing bacteria even with short exposure times. In
water, ozone (03) breaks down to 02 and 0- and
combines with organisms and chemicals. It also does not
leave any taste or residue, and is therefore very difficult
to detect to determine its effectiveness. With new de-
velopments in electronic technology, detection of the
short lived residual ozone in the water may become


economical in home water purification systems, but for
the present it is not a practical solution.
Addition of iodine into drinking water is a relatively
new approach to home water disinfection though the
technique has been around for years. It is very effective
on a wide variety of bacteria and does not affect the
water taste any more than chlorine. However, iodine is
not readily available and the cost is relatively high. It is
less reactive than chlorine and has less tendency to form
halogenated organic. Physiological effects of pro-
longed use of iodine, especially on children, are un-
known. However, in a newly developed system (the
resin-sequestered iodine system) the iodine remains
attached to the resin particles. It contacts the organisms
in the water and kills them. It does not move beyond the
filter or alter the taste of the disinfected water.
Distillation is an effective method for the removal of
microorganisms as well as many inorganic chemicals
from water. However, distillation alone is usually in-
effective in removing purgeable organic from the water
since some are carried into the distillate with water
vapor. Small units, producing 10 to 15 gallons per day,
for drinking and cooking are available for less than $300.
One must also remember a considerable amount of
energy is needed for the distillation process.

Activated Carbon Filters
Many people have turned to point-of-use activated
carbon filtration devices to improve their drinking wa-
ter. Installation of these filters is usually done for the
removal of offensive tastes and odors, color, chlorine,
and organic including halogenated organic compounds.
There are some water problems which are not cor-
rected by activated carbon filtration. If the water con-
tains large amounts of magnesium and calcium (hard
water), softening is still necessary because an activated
carbon unit will not remove hardness. It will not remove
dissolved metals such as iron, lead, manganese, and
copper or chlorides, nitrates, and fluorides. Small acti-
vated carbon units can remove only small portions of
hydrogen sulfide.
These filters are not effective against bacteria. In fact,
they may promote bacterial growth especially when not
used for a few days or when not changed at proper
intervals. Some manufacturers claim that filters contain-
ing silver discourage the growth of bacteria within the
filter. However, research shows that silver-impregnated
carbon units do not significantly reduce bacteria prob-
lems and may increase the silver content in drinking
water up to 0.028 mg/1.
Even with these limitations, activated carbon filters
can significantly improve water quality. Carbon filtra-
tion can remove more than 90% of cadmium, chro-
mium, manganese, mercury, silver, and tin. It removes
many objectionable tastes and odors. It is effective on









turbidity, but more economical sand or fiber filters
should be used if this is the only problem. But most of all
it is very effective for removal of chlorine and potentially
dangerous and carcinogenic organic compounds, which
may be present in a water system as a result of chlorina-
tion or industrial pollution.
High reduction efficiencies for halogenated organic
are reported by American Water Works Association
and will be discussed in the section on volatile organic
halide removal.
The efficiency of any activated carbon filter is depen-
dent on the "useful flow rate" of the filter and estimated
filter lifetime, which are governed largely by the size of
the filter and the amount of carbon it contains. There are
two basic types of carbon filters: sink-mounted, which
are attached to the faucet outlet, and in-line models
connected to the cold water supply line to the house or
just beneath the sink depending on the degree of the
problem. Quite often the effective lifetime of a carbon
filter can be short, which requires the filters to be re-
placed frequently. To determine the lifetime of a unit
requires knowledge of mean and peak flow rate, resi-
dence volume of unit, carbon surface area to volume
ratio, and the concentration of the various contaminants
in the water. This will require professional help by
trained water quality experts or a continuous testing
program for the water, which is usually cost prohibitive.
Some filters use powdered activated carbon embedded
in a felt-like pad and others use granular activated car-
bon. It has been found that powdered carbon has a
tendency to "unload" certain chemicals after it becomes
saturated and, therefore, units containing granular acti-
vated carbon are recommended.

Reverse Osmosis
Osmosis occurs when solutions of different concentra-
tions are separated by a semipermeable membrane. The
tendency to reach a state of equilibrium between the two
solutions (the second law of thermodynamics) causes
pressure to exist across the membrane, called osmotic
pressure. For example, if salty water and fresh water are
separated by a membrane, there is a pressure exerted by
the dissolved salt to pass through to the less salty solu-
tion, the fresh water, and there is a pressure exerted by
the fresh water to flow to the lower water concentration
existing in the salty water. If the membrane is permeable
to water molecules but not to salt, water will flow
through to dilute the salt water. If sufficient external
pressure is applied to the salty water solution, the flow of
water will be reversed. This process, called "reverse
osmosis" (RO), is slowly becoming technologically,
commercially, and economically feasible for the produc-
tion of high quality water from alkaline, brackish, or
colored water.
The rate of water flow is proportional to the pressure


applied to the higher concentration solution. This pres-
sure is called the feed pressure and its normal range is
100 to 600 lbs per square inch (p.s.i.); however, some
new home units run at 40 to 90 p.s.i. Since a semiperme-
able membrane acts in the system as a filter, its quality
and properties are of major importance. The membrane
should remove high percentages of dissolved solids,
have good chemical and bacteriological resistance, and
be able to operate under wide pH and temperature
ranges. Most membranes are subject to fouling by hard
water, making softening a required pretreatment. The
two most commonly used membranes are cellulose ace-
tate and nylon.
Research in North Dakota on the feasibility of reverse
osmosis systems in rural homes indicates that it is still a
costly process and should be considered for individual
houses only under extreme conditions. The quality and
useful life of membranes are being constantly improved
and this treatment may become cost-effective for indi-
vidual houses in the near future.
Supplying good quality drinking water to some of the
more rapidly growing coastal communities in Florida
has become a major problem. In several areas, desali-
nization is a feasible way of using brackish ground water
for potable supplies. The most common water treatment
technique used for these conditions is reverse osmosis,
which has been installed in more than 150 treatment
plants. Water treated by reverse osmosis may be desali-
nized to a degree that it can be blended with softened
brackish water to lower the cost of treatment, still meet-
ing the standards for potable water.
One of the major problems with the reverse osmosis
process is the disposal of the reject water, a high salt
concentration solution. If this water contains high levels
of toxic materials, special provisions for its disposal must
be made. Most reverse osmosis systems operate at a 50
to 75% conversion rate for brackish water and a 20 to
30% conversion rate for seawater. This means that, at a
75% conversion rate, 75 gallons of desalinized water will
be produced from 100 gallons of feed water and 25
gallons will be reject water. As a result, the total use of
water will be higher.
Water Softening
Hard water may be very troublesome in household
water supplies. Fortunately, there is a simple solution to
hard water problems. A water softener can be installed
in the cold water line that serves the house. Water for
the lawn, garden and other nonhousehold uses normally
bypasses the softener. Softened water is desirable in the
bathtub, lavatory, kitchen sink, and laundry room but is
undesirable as drinking water. For total household use,
the average family will need about 35 gallons per day of
softened water per person.
Water softeners usually consist of a tank containing an









ion-exchange material such as zeolite or resin beads.
When water passes through, calcium and magnesium
ions are exchanged for sodium ions. Water-softening
capacity must be regenerated at intervals depending on
the hardness of water and the capacity of softener. Wa-
ter softener capacity is given in terms of the number of
grains of hardness it will remove between successive
regenerations. It is recommended that a softener have
enough capacity to last at least three days between re-
generations. The choice will depend on water require-
ments for the household and the peak flow rate. Regen-
eration of the water softener is accomplished by flushing
brine (common salt solution) through the exchange
material to replace collected calcium and magnesium
ions with sodium ions. The flush brine is a waste and
must be disposed of properly.
Many softeners are fully automatic and require only a
periodic resupply of salt. They will automatically back-
wash before regenerating to flush out accumulated sedi-
ment and oxidized iron. The sodium content of the
softened water supply is directly related to the original
hardness. In harder water, more calcium and magne-
sium ions must be substituted with sodium during the
softening process. Some people may be concerned with
the increase of sodium in their diet; however, the quan-
tity of sodium obtained from the water will be relatively
small. For example, suppose that the hard water con-
tains 10 grains of calcium and magnesium. If we assume
that the daily consumption of water is one-half gallon
(2 liters) per person and one-third of the hardness is due
to magnesium salts and two-thirds to calcium salts, then
the increase in sodium in the daily diet is 0.3 g (this
assumes 100% efficiency of the exchange process). This
can be a significant amount for people limited to 0.5 g or
less of sodium per day.

Aeration and Other Methods for Removal
of Dissolved Gases
The process of aeration is used to improve the physi-
cal and chemical characteristics of water for domestic
use. The more important functions of this process are
the removal of dissolved gases, such as carbon dioxide,
methane, and hydrogen sulfide, and the addition of
oxygen necessary for the precipitation of iron and man-
ganese. However, oxygen entering the water may in-
crease its corrosiveness. If organic matter is not present,
aeration alone is sufficient to cause precipitation of iron
and manganese. Aeration can also partially remove
volatile substances causing problems with odor and
taste. However, since some substances are not suf-
ficiently volatile, aeration is not always efficient in the
removal of odor and taste. The use of aeration should
not be considered if water would be subjected to air-
borne contamination.
Other methods of oxidation can be used for removal


of dissolved gases like hydrogen sulfide. Oxidation is
necessary for conversion of the gas to forms which can
precipitate and therefore be filtered. It can be done
using oxidizing filters (green sand filters), chlorination,
or treatment with hydrogen peroxide, which has been
tested lately for this purpose.

Coagulation, Flocculation, Sedimentation,
and Filtration
A large portion of particles suspended in water can be
sufficiently small that their removal by sedimentation or
filtration is not practicable. Most of these small particles
are negatively charged which is the major cause of the
stability of suspended soil particles. Particles which
might otherwise settle are mutually repelled by these
charges and remain in suspension. Coagulation is a
chemical technique directed toward destabilization of
particle suspension. The most commonly used coagulant
is alum (aluminum sulfate). Coagulation is usually fol-
lowed by flocculation, which is a slow mixing technique
promoting the aggregation of the destabilized (coagu-
lated) particles. Coagulation followed by flocculation as
an aid to sedimentation and filtration has been practiced
for centuries. It is by far the most widely used process for
the removal of substances producing turbidity in water.
If water has high turbidity, flocculation followed by
sedimentation is often used to reduce the quantity of
material prior to entering the filter.
Filters for suspended particle removal can be made of
graded sand, granular synthetic material, screens of var-
ious materials, and fabrics. The most widely used are
rapid-sand filters in tanks. In these units, gravity holds
the material in place and the flow is downwards. The
filter is periodically cleaned by a reversal of flow and the
discharge of backflushed water into a drain. Cartridge
filters made of fabric, paper, or plastic material are also
common and are often much smaller and cheaper and
are disposable. Filters are available in several ratings
depending on the size of particles to be removed. Acti-
vated carbon filters, described earlier, will also remove
turbidity, but would not be recommended for that pur-
pose only.

Iron and Manganese Removal
If the amount of iron and manganese in water is not
very significant, it can be removed by most water soft-
eners along with water hardness. When the water soft-
ener is regenerated, iron and manganese ions will be
flushed out the same way as calcium and magnesium
ions. However, with larger amounts of iron in the water
(more than 0.1 mg/1), precipitated iron residue may
build up on the softening material regardless of back-
flushing and slowly decrease the efficiency of the soft-
ener. This can sometimes be controlled by special clean-
ing products mixed with the salt used for regeneration of









the softeners.
If the iron and manganese concentrations are above
0.1 mg/l (combination of both ions) an iron filter should
be used. The medium in this type of filter oxidizes iron
and manganese and removes precipitated matter. The
most common type is called a green sand filter. These
filters also must be flushed periodically and regenerated
with potassium permanganate to restore oxidizing
power.
The softener and iron filter are effective only if the
iron or manganese is not bound to organic matter and
there are no iron or manganese bacteria in the water.
The oxidizing media of the iron filters are not strong
enough to break these materials down. Where iron and
manganese are bound to organic matter, or concentra-
tions of these two metals are very high, or iron or man-
ganese bacteria are present, a strong oxidizing substance
must be applied before filtration. The most commonly
used chemical in these systems is household bleach
(hypochloride) injected ahead of the pressure tank. This
procedure disinfects the water and at the same time
oxidizes iron, manganese, and organic matter, which
will then precipitate. Sedimentation and/or filtration is
then needed to remove the precipitants. Chlorine solu-
tions tend to lose their strength and require weekly
addition to be effective. Activated carbon units or re-
verse osmosis units should then be used to remove the
remaining chlorine and possible halogenated hydrocar-
bons created from organic. It should be noted that acid
prevents the complete oxidation of iron in water and
acitity should be neutralized for effective removal of
iron. Final choice of the method will depend on iron and
manganese concentrations, pH of water, and the pres-
ence of the bacteria.
An alternative to iron removal is stabilization with
polyphosphates. The application of the polyphosphate
must take place before the iron is oxidized with aeration
or chlorination. This process is also called sequestration.
It does not work well where the concentration of iron is
over 1 mg/1. Also, heat will convert polyphosphate to
orthophosphate which causes it to lose its dispersing
properties. The use of phosphates may stimulate the
growth of bacteria so chlorination may still be required.
As a result, chlorine might as well be used for iron and
manganese removal in the first place.

Nitrate and Nitrite Control
Often the best solution for nitrate and nitrite pollution
is relocation of the well or drilling the well deeper into an
uncontaminated aquifer. The only effective methods of
treatment are distillation and reverse osmosis but these
will often not be economically feasible. Activated car-
bon filters will not remove nitrates or nitrites.
Volatile Organic Halide Removal
The only effective methods for removing volatile


organic halides are activated carbon filtration and re-
verse osmosis. Reverse osmosis would be feasible only if
other problems required its use. Studies done by The
American Water Works Association show that the re-
duction efficiency for halogenated organic by activated
carbon filters ranges from 76% for a faucet-mounted
unit to 99% for several larger in-line units. However,
one must keep in mind that the reduction is dependent
on flow rate, contact time, and cleanliness of the unit as
discussed in the section on these filters.

Trace Metals Removal
Methods for the removal of trace amounts of toxic
metals include distillation, ion exchange, reverse osmo-
sis, and activated carbon filtration. All systems are quite
expensive and are usually installed on drinking water
lines only. The ion-exchange resins must be selected
very carefully with regard to the metals needing removal
and other metals present in the water which may interact
with the process. The other three methods, distillation,
reverse osmosis, and activated carbon filtration, and
their limitations were described earlier.

Corrosion Control in Household Systems
If the main cause of water corrosiveness is low pH
(acidity), the water can be neutralized using special
filters containing such materials as calcium carbonate
(calcite) or magnesium oxide (magnesia). These filters
serve also as mechanical filters and therefore must be
backwashed periodically with some additional active
material added. Another method of neutralization re-
quires the addition of sodium carbonate (soda ash) into
the system. This should be injected ahead of the pres-
sure tank. If chlorination is used, this solution can be
mixed with the chlorine solution.
One has to keep in mind that addition of soda ash may
slightly increase sodium level in the drinking water, and
calcium carbonate filters will increase hardness and
alkalinity.
A different approach to the control of corrosion is the
injection of certain chemicals, such as polyphosphates
and silicates, to create protective films on plumbing
components. Selection of noncorrosive plumbing mate-
rials, like plastic or polyvinyl chloride, will help. Since
corrosion increases with elevated temperatures, water
heaters should be set only as high as necessary and
temperatures above 1400F are not recommended.
Corrosion associated with other chemicals like hydro-
gen sulfide and dissolved oxygen must be handled dif-
ferently. For example, hydrogen sulfide can be treated
by activated carbon filtration or chlorination.

Summary
People are becoming increasingly concerned about
the safety of their water. Current improvements in









analytical methods allow for detection of impurities at
very low concentrations in water. Consequently, water
supplies once considered to be pure are found to contain
various contaminants, very often from natural sources,
and usually below harmful concentrations. Water can
dissolve thousands of substances, some of which do not
dissolve and form a suspension in water. Therefore, we
must not expect pure water, but we want to be sure of
safe water.
Water systems in Florida that serve more than 1000
residents are periodically tested for many kinds of con-
tamination. In the near future this type of testing will be
required for every community water supply (more than
15 residents). The only people who may have a reason
for testing their water are the owners of individual water
supplies that have some indication of a problem, such as
odor or taste. The presence of nearby pollutant sources
also may be a good reason for a water test.
This circular should be considered an introduction to
some specific water problems one might encounter in
Florida, and how one should go about identifying and
solving them. For more specific information contact
your local county extension office.

References
American Society of Agricultural Engineers. 1979.
Quality Water for the Home and Farm: Proceedings of
the Third Domestic Water Quality Symposium. Publi-
cation 1-79. St. Joseph, MI 49085-9659.
American Water Works Association. 1971. Water
Quality and Treatment: a Handbook of Public Water
Supplies. McGraw-Hill Book Company, New York.


Bell, F.A. Jr., D.L. Perry, J.K. Smith and S.C.
Lynch. 1984. Studies on home water treatment systems.
J. Am. Water Works Assoc. 76:126-130.
Dykes, G.M. 1983. Desalting water in Florida. J. Am.
Water Works Assoc. 75:104-107.
Environmental Protection Agency. 1979. Methods of
Chemical Analysis of Water and Waste. US-EPA-600/
4-79-020. Washington, D.C.
Fair, G.M., J.C. Geyer and D.A. Okun. 1968. Water
and Wastewater Engineering. Vol. 1 and 2. John Wiley
and Sons, Inc., New York.
Florida Department of Environmental Regulation.
1982. Florida Administrative Code Title 17, Chaps. 21-
22. Tallahassee, FL.
Forstner U., and G.T.W. Wittmann. 1979. Metal
Pollution in the Aquatic Environment. Springer-
Verlag, Berlin.
Freeze, K.A., and L.A. Cherry. 1979. Groundwater.
Prentice-Hall, Englewood Cliffs, NJ.
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This publication was produced at a cost of $4285, or 30.6 per copy, to increase knowledge of home
water quality and safety and to discuss possible treatments of contamination. 7-14M-86


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