MONITORING THE SANITARY BACTERIOLOGICAL
QUALITY OF POTABLE WATER SUPPLIES
FEDERAL WATER QUALITY ADMINISTRATION
NORTHWEST REGION
ALASKA WATER LABORATORY
College, Alaska
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MONITORING THE SANITARY BACTERIOLOGICAL
QUALITY OF POTABLE WATER SUPPLIES
by
Ronald C. Gordon, Ph.D.
Research Microbiologist
Presented at the
Alaska Water Management Association Seminar
Fairbanks, Alaska, October 23, 1970
for the
FEDERAL WATER QUALITY ADMINISTRATION
DEPARTMENT'OF THE INTERIOR
ALASKA WATER LABORATORY
COLLEGE, ALASKA
Working Paper No. 10
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MONITORING THE SANITARY BACTERIOLOGICAL
QUALITY OF POTABLE WATER SUPPLIES
The available information indicates that many public water supplies
in Alaska do not comply with all the minimum public health standards
which ensure a safe water supply. There are supplies that comply with
none of the standards such as the use of raw water, and others that
perhaps comply with all of them. One of the most neglected areas of com-
pliance is adequate monitoring of the bacteriological quality.
Numerous pathogenic (disease causing) bacteria and viruses are
potentially present in water. None of these microorganisms are found
naturally in water and most of them enter the water as a result of the
activities of man or other warm blooded animals and birds both domestic
and wild (5). Fecal material, from individuals with an active disease or
from persons called carriers, is generally the source of water borne
pathogens. However, some pathogens such as leptospires may be shed only in
the urine. Carriers are usually persons who have recovered from the
disease but still harbor and excrete highly infective pathogens, such as
the bacterium causing typhoid fever. The numbers and even the very presence
of any specific pathogen in water varies with the geographic area, state of
community health, nature and degree of waste treatment and other factors (5),
Regardless of whether communities obtain their public water supply
from wells, surface water reservoirs or streams, they are potentially sus-
ceptable to fecal pollution. Wells may be contaminated from sources such
as septic tank effluents which seep into the water table or from surface
water runoff into the top or along the casing of poorly constructed or
damaged wells.
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Reservoirs and streams may be contaminated by surface pollution from
humans, birds or animals'within the watershed, seepage of contaminated
ground water, or from sewage effluents upstream. Water distribution
systems are also susceptable to contamination through cross connection
and/or loss of pressure within the system. These are not necessarily all
of the potential sources of contamination, but will serve to illustrate
the many ways that fecal material may enter a potable water supply. One
well documented case of a village having a polluted water supply
occurred in 1969 when it became necessary for the old village of
Minto to obtain its water supply from the Tanana River. A sampling
station for a fecal indicator bacteria survival study being conducted
at the Alaska Water Laboratory was located directly in front of the
village. The river water at this station was found to contain more
total coliconn bacteria than permitted in any water source to be used
for drinking purposes (an average of 2,200 total coliforms per 100 ml
throughout the two week period of the study).
The microorganisms which are significant from a public health view-
point are the pathogens. They may be present only sporadically or at
best in low numbers, and the methods for detecting the presence of many of
the pathogenic bacteria and all viruses are still in a rather primitive
state. However, the potential presence of pathogenic bacteria is
routinely determined using indicator bacteria. It was pointed out pre-
viously that most pathogens which may be found in water are of fecal
origin. Therefore, the bacteriological quality of water is determined
routinely only in relation to fecal pollution.
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The enteric (intestinal) bacteria which most nearly meet the require-
m^nts.as indicators of the potential presence of pathogenic bacteria are
divided into two general groups, total coliforms and enterococci. These
bacterias which are normal inhabitants of the intestinal tracts of warm
blooded animals, are present in fecal material in large numbers and their
presence is easily determined by routine examination of the water. These
groups can be divided into additional subgroups for specific studies, but
for routine monitoring no further division is used. Bacteria of the
coliform group are present in the largest numbers in the intestinal tract
of warm blooded animals, and are the easiest to work with for routine
monitoring of the bacterial quality of potable water supplies and sewage
treatment plant effluents.
The definition of the total coliform group is as follows: "The
coliform group includes all aerobic and facultative anaerobic, gram-
negative, nonsporeforming rod-shaped bacteria which ferment lactose with
gas formation within 48 hours at 35° C" (3). This definition encompasses
a large group of closely related bacteria most of which are normal in-
habitants of the intestinal tract of warm blooded animals. The few members
which are considered vegetative types (not of fecal origin) do not detract
from the usefulness of this group of bacteria for monitoring the sanitary
condition of water.
It should be obvious that the sanitary bacteriological quality of
potable water requires regular monitoring if a safe public water supply
is to be maintained. However, bacteriological quality is not the only
consideration. The Alaska Administrative Code (4) sets forth two require-
ments for public water supplies:
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(1) (A) "Such water shall be obtained from a source which is
- properly located, constructed and adequately protected
against contamination."
(B) "Such water shall be properly and adequately purified."
(2) "All such water shall not show upon analysis a chemical
content deleterious to the public health, as specified by
the Alaska Drinking Water Standards."
If the source does not meet the physical requirements of location, con-
struction and protection, the supply can not be considered safe even
though analyses indicate that the water quality requirements are met (6,
7).
After the best possible water source has been selected and found to
meet the chemical standards, either naturally or by treatments then the
sanitary bacteriological quality is considered. The density of total
coliforms is used to establish the bacteriological quality of water for
public health purposes. Total coliform density is reported as the
number of total coliforms per 100 ml of water. Two coliform levels
for raw water to be treated for public consumption are recognized by
the State of Alaska Water Quality Standards (1). The first level is
raw water which averages less than 50 total coliforms per 100 ml in
any month. This water can be used after simple disinfection and removal
of naturally occurring impurities. The second level is raw water which
averages less than 2000 total coliforms per 100 ml. This water requires
adequate treatment equal to coagulation, sedimentation, filtration, disin-
fection, and any additional treatment necessary to remove naturally present
impurities.
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Untreated (raw) water is used extensively for drinking purposes
in Alaska. It should be noted that there is no provision in the Water
Quality Standards which establishes the quality of water to be used
without any form of treatment.
The 1962 Public Health Service Drinking Water Standards (6) are used
by the State of Alaska to establish the minimum quality for public water
supplies. These standards state that samples for bacteriological examin-
ation shall be collected at representative points throughout the distri-
bution system. The frequency of sampling and the location of sampling
points shall be established jointly by the reporting agency and the
certifying authority after investigation of the source, method of treat-
ment and protection of the water concerned. The presence of coliform
bacteria in the samples of treated water shall not exceed the following
limits when the membrane filter technique is used:
"The arithmetic mean coliform density of all standard samples
examined per month shall not exceed one per 100 ml. Coliform colonies
per standard sample shall not exceed 3 per 50 ml, 4 per 100 ml, 7 per
200 ml or 13 per 500 ml in
(a) two consecutive samples;
(b) more than one standard sample when less than 20 are examined
per month;
or (c) more than five percent of the standard samples when 20 or more
are examined per month.
When coliform colonies in a single standard sample exceed the above
values, daily samples from the same sampling point shall be collected
promptly and examined until the results obtained from at least two con-
secutive samples show the water to be of satisfactory quality."
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Samples for water quality analysis (from both public and private water
supplies) are examined in laboratories maintained in Fairbanks, Anchorage
and Juneau by the Alaska Department of Health and Welfare. The procedure
for submitting samples for analysis is quite straight-forward and details
can be obtained by contacting one of these offices. The personnel in
these laboratories can provide satisfactory analyses only if the local
operator submits valid samples. Valid samples are collected using proper
sampling techniques, from representative locations in the system at pre-
established intervals, and reach the laboratory promptly for analysis.
Even if the local operator obtains valid samples, the time loss
between sample collection and laboratory analysis leaves room for con-
siderable doubt concerning the value of the results. A.P.M.A. Recom-
mended Procedures for the Examination of Seawater and Shellfish (2)
states that bacteriological analysis should be started within one hour
after .sample collection. However, if a delay is necessary the samples
should be kept at a temperature below 10° C, but not frozen, until examined,
and samples should not be held more than 30 hours. Less than 30 hour
delivery of any mailed parcel from a remote area is highly improbable
and temperature control is even less likely. Extensive delays in analysis
may result in the death of coliform bacteria in the samples and thus give
a false indication of the water quality. In the event that a water supply
has become contaminated, there is a minimum two day lapse between sampling
and return of results to the operator, and the time span may well be much
longer. If contamination of a water supply had occurred, an outbreak
of a v/ater-borne disease could occur during this delay if the operator
waits for the results before initiating corrective action.
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It is possible to shorten the elapsed time between sampling and
receiving of results to 24 hours. The methodology and equipment are
available and the basic procedure is quite simple. However, the persons
responsible for providing and maintaining public water supplies must show
a continuing interest before the details of the procedure can be worked
out in a useable form. The essence of the procedure is for the operator
to conduct routine bacteriological analyses on site. This requires a
small outlay of funds for equipment and operator training.
The membrane filter procedure has received wide acceptance for
analyzing the bacteriological quality of water. This procedure is rela-
tively simple and produces reliable results in the hands of an operator
who has acquired the minimum but essential training. The Federal Water
Quality Administration has the capability of providing the necessary training.
A five day course, offered periodically throughout the country, is open
to attendance by all interested persons. If there is sufficient demand,
the course can be scheduled for presentation in Alaska, preferably at
the Alaska Water Laboratory in Fairbanks where laboratory space and
equipment are available. Perhaps, when the details of the operational
procedure are established, it may be found that the requirements for
training differ sufficiently from the existing course to warrant the
development of a three or four day course specifically for the Alaska
need. The FWQA is available to help fill the need on request.
The equipment for bacteriological analysis of water can be obtained
for a fairly low initial investment. A great deal of money can be in-
vested in equipment, but this isjiot necessary unless extensive studies,
where a large number of samples must be handled in a short time, are
planned. In addition to on site requirements, there is a very important
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role for a central support laboratory. This role includes logistic sup-
^p'ortf and, probably the most important, technical advice for the local
operator in maintaining the quality of his work, finding the source and
eliminating contamination when it occurs, and other support which may be
desirable or appropriate.
The author feels strongly that the bacteriological monitoring of
water supplies must be improved. It is hoped that this paper will stimu-
late further discussions and that a workable system can be developed with
the participation of all concerned groups.
Of course, along with maintaining and improving the water supply,
another means of reducing the potential hazard of contamination is to
improve sewage collection, treatment, and disposal systems.
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References
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1. Alaska Department of Health and Welfare, Water Quality Standards for
Interstate Waters Within the State of Alaska and a Plan for Imple-
mentation and Enforcement of the Criteria (1967).
t
2, American Public Health Association, Inc., Recommended Procedures for
the Examination of Sea Water and Shellfish, 4th Edition (1970).
3. American Public Health Association, American Water Works Association,
and Water Pollution Control Federation, Standard Methods for the
Examination of Water and Wastewater, 12th Edition, American Public
Health Association, Inc. (1965).
4. Division of Public Health, Alaska Department of Health and Welfare,
"Sanitation and Engineering," Administrative Code, Title 7 - Division
1, Chapter 2.
5, Federal Water Pollution Control Administration Training Program,
Current Practices in Water Microbiology, U.S. Dept. of the Interior
"___
6. Public Health Service, Public Health Service Drinking Water Standards,
1J)6JU P.H.S. Publication No. 956, U.S. Dept. of Health, Education and
Welfare (1962).
7. Public Health Service, Manual for Evaluating Public Drinking Water
Supplies. P.H.S. Publication No. 1820, U.S. Dept. of Health, Education
arid Welfare (1969),
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