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Historical
Note
As noted by Baker (1949), the quest for pure water began in prehistoric
times. Recorded knowledge of water treatment is found in Sanskrit
medical lore and in Egyptian inscriptions. Pictures of apparatus to clarify
liquids (both water and wine) have been found on Egyptian walls dating
back to the fifteenth century B.C. Boiling of water, the use of wick
siphons, filtration through porous vessels, and even filtration with sand
and gravel, as means to purify water, are methods that have been
prescribed for thousands of years. In his writings on public hygiene,
Hippocrates (460-354 B.C.) directed attention principally to the impor-
tance of water in the maintenance of health, but he also prescribed that
rain water should be boiled and strained. The cloth bag that he
recommended for straining became known in later times as "Hippoc-
rates' sleeve."
Public water supplies, already developed in- ancient times, assumed
added importance with the progressive increase in urbanization. But
though they were clearly beneficial in distributing water of uniform
quality, large numbers of people ran the risk of suffering adverse effects
when the water was unsafe to drink.
The first clear proof that public water supplies could be a source of
infection for humans was based on careful epidemiological studies of
cholera in the city of London by Dr. John Snow in 1854 (Snow, 1855~.
Adthough Snow's study of the contaminated Broad Street pump is the
most famous, his definitive work concerned the spread of cholera through
water supplied by the Southwark and Vauxhall Company and the
1
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2 DRINKING WATER AND H"LTH
Lambeth Company. The former obtained its water from the Thames at
Battersea, in the middle of London in an area almost certainly polluted
with sewage, whereas the Lambeth Company obtained its water
considerably upstream on the Thames, above the major sources of
pollution. In one particular area served by these two companies,
containing about 300,000 residents, the pipes of both companies were laid
in the streets, and houses were connected to one or the other sources of
supply. Snow's examination of the statistics of cholera deaths gave
striking results. Those houses served by the Lambeth Company had a low
incidence of cholera, lower than the average for the population of
London as a whole, whereas those served by the Southwark and Vauxhall
Company had a very high incidence. As the socioeconomic conditions,
climate, soil, and all other factors were identical for the populations
served by the two companies, Snow concluded that the water supply was
transmitting the cholera agent. Snow's study, a classic in the field of
epidemiology, is even more impressive when it is realized that at the time
he was working, the germ theory of disease had not yet been established.
During the seventeenth to the early nineteenth centuries, a number of
improvements in water supply were made, most of them related to
improvements in filtration to remove the turbidity of waters. During this
same period, the germ theory of disease became firmly established as a
result of research by Louis Pasteur, Robert Koch, and others, and in 1884
Koch isolated the causal agent of cholera, Vibrio cholera.
Importance of Water Filtration
In 1892, a study of cholera by Koch in the German cities of Hamburg
and Altona provided some of the best evidence of the importance of
water filtration for protection against this disease (Koch, 18941. The cities
of Hamburg and Altona both received their drinking water from the Elbe
River, but Altona used filtration, since its water was taken from the Elbe
below the city of Hamburg and hence was more grossly contaminated.
Hamburg-and Altona are contiguous cities, and in some places the border
between the two follows a contorted course. Koch traced the incidence of
cholera in the 1892 epidemic through these two cities, with special
attention directed to the contiguous areas. In such areas it was assumed
that climate, soil, and other factors would be identical, the principal
variable being the source of water. The results of this study were clear-
cut: Altona, even with an inferior water source, had a markedly lower
incidence of cholera than Hamburg. Since by this time it was well
established that cholera was caused by intestinal bacteria excreted in
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Historical Note 3
large numbers in the feces, it was concluded that the role of filtration was
to remove the contaminating bacteria from the water.
In the United States, cholera was not a problem after the mid-
nineteenth century; the waterborne disease of particular concern was
typhoid fever. In England, William Budd had shown by the mid-
nineteenth century that typhoid fever was a contagious disease, and the
causal agent was isolated and identified by Eberth in 1880 and Cranky in
1884 (Wilson and Miles, 1957~. Although the causal agent, now called
Salmonella Delhi, is transmitted in a variety of ways, one of the most
significant is by drinking water.
Experiments on water filtration were carried out in the United States
during the late 1880's and early 1890's, notably by the Massachusetts State
Board of Health experiment station established in 1887 at the city of
Lawrence. At this station the treatment of water as well as sewage was
considered by an interdisciplinary group that included engineers,
chemists, and biologists. A leader in this work was W. T. Sedgwick, a
professor at the Massachusetts Institute of Technology (MID], and MIT's
influence on water-supply research remained strong throughout the first
quarter of the twentieth century. Much of the history of this work has
been reviewed by Whipple (1921) and in the two editions of Hazen's book
(1907, 1914~; the technical aspects are discussed and clearly illustrated by
Johnson (1913~. One important technological advance that made water
filtration adaptable even to rather turbid sources of water was the use of
chemical-coagulation filtration processes, patented about 1884 by the
brothers J. W. and I. S. Hyatt.
While the Lawerence experiments were going on, an epidemic of
typhoid swept through the city, hitting especially hard at those parts that
were using the Merrimac River as its.water supply. As a result, the city of
Lawrence built a sand filter, and its use led a marked reduction in the
typhoid fever incidence. As reported by Hazen (1907), the death rate from
typhoid fever in Lawrence dropped 79% when the 5-yr periods before and
after the introduction of the filter were compared. Of additional interest
was a reduction in the general death rate (all causes) of 10%, from 22.4 to
19.9 per 1,000 living.
Another major series of filtration experiments were made in 1895-1897
at Louisville, Ky., where the source of water was the muddy and polluted
Ohio River. These experiments were successful, and from an engineering
point of view were of importance because they showed that it was
possible to treat source waters of a rather poor quality (the Merrimac
River at Lawrence may have been polluted, but at least it was a clear
water, making filtration rather easier.) The success of the Louisville
experiments and the other studies led to rapid establishment of filters as a
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4 DRINKING WATER AND H"LTH
means of water purification; by 1907 Hazen could list 33 cities in the
United States, some of comparatively large size, which were using
mechanical filters, and 13 cities that were using slow sand filters. As
discussed by Hazen, filtration led to an elimination of turbidity and color
from the water, and to a removal of about 99% of the bacteria present. At
that time these conditions were considered as a standard by which the
quality of a treated water should be judged. As Hazen states: "There is no
final reason for such standards. They have been adopted by consent
because they represent a purification that is reasonably satisfactory and
that can be reached at a cost which is not burdensome to those who have
to pay for it ... . There is no evidence that the germs (characteristic of
sewage pollution) so left in the water are in any way injurious. Certainly if
injurious influence is exercised it is too small to be determined or
measured by any methods now at our disposal." This last statement is of
considerable importance when considered in the light of the important
advance in water purification practice yet to come, chlorination.
An excellent overview of the relationship between water quality and
typhoid fever incidence was published at about this time by Fuertes
(18971. He gathered typhoid fever statistics for a large number of cities in
North America and Europe and grouped the data by type of source water
and water treatment.
Chlorination, The Most Significant Advance in Water Treatment
Although a reading of Hazen's 1907 book might lead one to conclude that
excellent water quality had been well established by filtration, the most
important technological advance in water treatment was yet to come. The
introduction of chlorination after 1908 provided a cheap, reproducible
method of ensuring the bacteriological quality of water. Chlorination has
come down to us today as one of the major factors ensuring safety of our
drinking water.
Calcium hypochlorite was manufactured industrially for use as a
bleaching powder and was used in paper mills and textile industries. It
was a cheap chemical, and hence readily adaptable to use on the large
scale necessary for drinking water. The first practical demonstration in
the United States of its use in water supply was at the filter plant of the
Chicago Stock Yards, where it was introduced by Johnson in the fall of
1908 (Johnson, 1913~.
The use of chlorination in an urban water supply was introduced in
Jersey City, N.J., in the latter part of 1908. The circumstances surround-
ing the Jersey City case are of some interest from a historical point of
view and will be briefly reviewed. Jersey City received its water from a
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Historical Note 5
private company that used a large reservoir at Boonton, an impoundment
of the Rockaway River. The water was supplied to the city unfiltered,
although some settling took place in the reservoir. Several years before
1908 the city raised the contention that the water being supplied was not
at all times pure and wholesome for drinking, as was required by the
terms of its contract with the private company. At certain times of the
year, the water in the reservoir became polluted as a result of sewage
influx from communities on the river above the reservoir. Rather than
undergo the expense of a filtration plant, or attempt to control the sewage
influx from the various communities, the private company chose to
introduce a chlorination system. The results were dramatic. A marked
drop in total bacterial count was obtained, and at a cost far lower than
any other procedure. After many months of operation, further testimony
before the court was held, to determine whether the company, was
meeting its contract, and the court decided that the evidence was
favorable to the company. As stated by the court examiner: "I do
therefore find and report that this device [chlorination] is capable of
rendering the water delivered to Jersey City pure and wholesome for the
purposes for which it is intended and is effective in removing from the
water those dangerous germs which were deemed by the decree to
possibly exist therein at certain times."
The dramatic effect that chlorination had on water-supply problems is
well illustrated by comparing the first and second editions of Hazen's
book (1907 and 19141. In the first edition, barely any mention of
disinfection is made (merely a remark about ozone being too expensive),
but in the second edition Hazen waxes enthusiastic about the advantages
of chlorination. As he says, chlorination could be used "at a cost so low
that it could be used in any public waterworks plant where it was required
.
tar ariv~nt~a`~ When the advantages to be obtained by this
~ ~'.'~t)-~ Be . . . . .... ..
simple and inexpensive treatment became realized, as a result of the
n'~hlicitv given bv the JerseY Citv experience, the use of the process
rim ~ ~ , , ,
. . ... ~ ~ ~ - 1-, ~.-1 _~ ~ ~ ~ {llilAN
extended with unprecedented raplulty, until al Ine present slyly' ills
greater part of the water supplied in cities in the United States is treated
in this way or by some substitute and equivalent method."
Interestingly from the point of view of the present report, the
introduction of chlorination also changed markedly the established ideas
about water-quality standards: "The use of methods of disinfection has
changed these standards radically. By their use it has been found possible
to remove most of the remaining bacteria so that the water supplied can
be as easily and certainly held within one-tenth of one percent of those in
the raw water, as it formerly could be held within one percent ....
Even today the limit has not been reached. It may be admitted that the
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6 DRINKING WATER AND H"LTH
time will come when a still higher degree of bacterial efficiency will be
required. Present conditions do not seem to demand it, but we must
expect that in some time in the future conditions will arise which will
make it necessary. When additional purification is required it can be
furnished." (Hazer, 1914~.
The importance of Hazen's book is that Hazen was a major consulting
engineer for a wide variety of water works, and was very influential in
recommending treatment methods. Chlorination was introduced at about
the time that adequate methods of bacteriological examination of water
had developed, permitting an objective evaluation of the efficiency of
treatment. This evaluation was not based on the incidence of typhoid
fever directly, but was based on an indirect evaluation using bacterial or
coliform counts.
Soon after chlorination was introduced, it was possible to obtain firm
epidemiological evidence that cities chlorinating water had lowered
incidences of typhoid fever (G. C. Whipple, 1921~. Filtration was
introduced in 1906 and chlorination in 1908, and both led to marked
reductions in the incidence of typhoid fever. Another dramatic example
derives from observations at Wheeling, W.Va., in 1917-1918 (Gainey and
Lord, 1952~. The incidence of typhoid fever in Wheeling was 155-200 per
100,000 during these years. Chlorination was introduced in the latter part
of 1918, with the result that during the first 3 months of 1919 only seven
cases were recorded. For 3 weeks during April 1919 chlorination was
discontinued, with the result that the number of cases increased to 21, or a
300% increase. Chlorination was continued thereafter, and only 11 cases
were recorded for the last 6 months of the year. Other examples of this
sort could be cited (Gainey and Lord, 1952~.
Summary
We thus see that by the beginning of World War I the essential features of
water purification techniques were known, and their worth }lad been well
established. Since that time there have been many refinements made at an
engieering level, but no changes in the basic concepts. It is clear that the
prime motivation for the development and introduction of purification
methods has been to protect the public health, with special concern for
controlling the spread of typhoid fever. An ancillary consideration has
been esthetics, showing concern for the appearance, taste, and odor of the
water.
One point worth emphasizing is that the availability of adequate
treatment methods has influenced the standards for drinking water. This
point was implied in the books by Hazen (1907 and 1914), but is most
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Historical Note 7
clearly seen in the preamble to the 1925 Federal Standards, which
superseded the brief 1914 Standards (see Standard Methods, 7th edition,
1933, p. 136, for the complete 1925 Standards). The following quote is
relevant:
The first step toward the establishment of standards which will insure the safety of
water supplies conforming to them is to agree upon some criterion of safety. This
is necessary because "safety" in water supplies, as they are actually produced, is
relative and quantitative, not absolute. Thus, to state that a water supply is 'safe'
does not necessarily signufy that absolutely no risk is ever incurred in drinking it.
What is usually meant, and all that can be asserted from any evidence at hand, is
that the danger, if any, is so small that it cannot be discovered by available means
of observation. Nevertheless, while it is impossible to demonstrate the absolute
safety of a water supply, it is well established that the water supplies of many of
our large cities are safe In the sense stated above, since the large populations using
them continuously have, In recent years, suffered only a minimal incidence of
typhoid fever and other potentially waterborne infections. Whether or not these
water supplies have had any part whatsoever in the conveyance of such infections
during the period referred to is a question that cannot be answered with full
certainty; but the total incidence of the diseases has been so low that even though
the water supplies be charged with responsibility for the maximum share which
may reasonably be suggested, the risk of infection through them is still very small
compared to the ordinary hazards of everyday life.
At present other considerations make it necessary [for us] to be less
confident than was the 1925 Committee on Standards. Typhoid fever and
Cholera are dramatic diseases whose causal agents are transmitted by the
water route. Typhoid fever statistics have provided some of the best
evidence of the efficacy of treatment systems, but it should be kept in
mind that other diseases, not so easily diagnosed, might also be kept
under control at the same time. The so-called Mills-Reincke theorem held
that, for every death from waterborne typhoid, there were several deaths
from other diseases for which the causal agents were transmitted by water
(Shipple, 1921~. At present, the incidence of typhoid fever in the United
States is so low that no useful information on the electiveness of recent
changes in water-purification practices can be obtained from an
examination of the statistics. During the years 1946-1970, there were 53
outbreaks of waterborne infectious disease due to typhoid, but there were
297 outbreaks due to other bacterial or viral agents, including 178
outbreaks of gastroenteritis of undetermined etiology (Craun and
McCabe, 1973~. Of the outbreaks, 71 percent resulted from contamination
of private water systems, but most of the illness (echo) was associated with
community water systems. During the period 1946-1960 there were 70
outbreaks of waterborne disease in communities served by public utilities
(Weibel et al., 1964), of which only 6 were typhoid fever. When data
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~ DRINKING WATER AND H"LTH
during this period for the number of outbreaks are examined, the
incidence of typhoid is even lower 103 cases out of a total of 19,928 (for a
percentage of O.5~o). Even considering that typhoid is more likely to be
fatal than infectious hepatitis or gastroenteritis of unknown etiology, the
Mills-Reincke theorem does seem to have considerable merit. Thus, the
rationale that has been used in devising standards for microbiological
contaminants (see quotation above from the 1925 Standards) does not
necessarily hold up on careful examination. The coliform standards may
have ensured freedom from typhoid fever, but we do not have the same
assuredness that they have guaranteed freedom from other infections.
Even granted that most of the outbreaks reported have occurred because
of breakdowns in the proper functioning of water systems, the results
show that intestinal infections other than typhoid are common and,
because of their often ill-defined nature, may be improperly diagnosed.
Finally, only "outbreaks" find their way into public health statistics,
whereas sporadic, random cases of gastroenter~tis generally go unreport-
ed. The epidem~ological significance of the present microbiological
standards warrants continuing investigation to bring about further
refinements in meeting the goal of maximum protection of public health.
REFERENCES
Baker, M.N. 1949. The Quest for Pure Water. Am. Water Works Assoc., New York.
Craun, G.F., and L. J. McCabe. 1973. Review of the causes of waterborne-disease outbreaks.
J. Am. Water Works Assoc. 65 :74.
Fuertes, J.H. 1897. Water and public health. John Wiley, New York.
Gainey, P.L., and T.H. Lord. 1952. Microbiology of water and sewage. Prentice-Hall, Inc.,
New York.
Hazen, A. 1907. Clean water and how to get it, 1st ed. John Wiley, New York.
Hazen, A. 1914. Clean water and how to get it, 2d ed. John Wiley, New York.
Johnson, G.A. 1913. The purification of public water supplies. U.S. Geol. Surv. Water-
Supply Paper 315.
Koch, R. 1894. Professor Koch on the Bacteriological Diagnosis of Cholera, Water-filtration
and Cholera, and the Cholera in Germany during the Winter of 1892-93. Translated by G.
Duncan David Douglas, publisher, Edinburough.
Snow, J. 1855. A reprint of two papers by John Snow, M.D., 1936. The Commonwealth
Fund, New York.
Weibel, S. R., F. R. Dixon, R. B. Weidner, and L.J. McCabe. 1964. Waterborne-disease
outbreaks, 1946-60. J. Am. Water Works Assoc. 56:947-958.
Whipple, G.C. 1921. Fifty years of water purification. In M.P. Ravenel, ed. A Half Century of
Public Health, pp. 161-180. American Public Health Association, New York. (Reprinted
1970 by the Arno Press and the New York Times.)
Representative terms from entire chapter:
drinking water
