Cross-Connection
Control Manual
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Office of Water (4606M)
EPA816-R-03-002
www.epa.gov/safewater
February 2003 Printed on Recycled Paper
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vvEPA Cross-Connection
Control Manual
United States
Environmental Protection Agency
Office of Water
Office of Ground Water and Drinking Water
First Printing 1973
Reprinted 1974, 1975
Revised 1989
Reprinted 1995
Technical Corrections 2003
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Preface
Thumbing cross-connections,
.[which are defined as actual
or potential connections
between a potable and non-
potable water supply, constitute
a serious public health hazard.
There are numerous, well-
documented cases where cross-
connections have been respon-
sible for contamination of
drinking water, and have
resulted in the spread of disease.
The problem is a dynamic one,
because piping systems are
continually being installed,
altered, or extended.
Control of cross-connec-
tions is possible, but only
through thorough knowledge
and vigilance. Education is
essential, for even those who are
experienced in piping installa-
tions fail to recognize cross-
connection possibilities and
dangers. All municipalities with
public water supply systems
should have cross-connection
control programs. Those
responsible for institutional or
private water supplies should
also be familiar with the
dangers of cross-connections
and should exercise careful
surveillance of their systems.
This Cross-Connection Control
Manual has been designed as a
tool for health officials, water-
works personnel, plumbers, and
any others involved directly or
indirectly in water supply
distribution systems. It is
intended to be used for educa-
tional, administrative, and
technical reference in conduct-
ing cross-connection control
programs. This manual is a
revision of an earlier book
entitled Water Supply and
Plumbing Cross-Connections (PHS
Publication Number 957),
which was produced under the
direction of Floyd B. Taylor by
Marvin T Skodje, who wrote
the text and designed the
illustrations.
Many of the original
illustrations and text have been
retained in this edition. Previ-
ous revisions were done by
Peter C. Karalekas, Jr. with
guidance from Roger D. Lee
incorporating suggestions made
by the staff of the EPA Water
Supply Division, other govern-
mental agencies, and interested
individuals.
This 3rd edition was
produced as a result of an
updated need for cross-
connection control reference
material reflecting an increase
in cross-connection control
activity throughout the United
States. It has been revised and
re-issued reflecting a demand
for its use, together with
requests for a document that
covers the broad spectrum of
cross-connection control from
both the basic hydraulic
concepts through the inclusion
of a sample program that can
be a guide for a program at the
municipal level. New backflow
devices have been included in
this revision that are now being
produced by manufacturers
reflecting the needs of the
market. Updated actual cross-
connection case histories have
been added containing graphic
schematic illustrations showing
how the incidents occurred and
how cross-connection control
practices could be applied to
eliminate future re-occurrence.
A more detailed explanation of
cross-connection control
"containment" practice has
been included together with the
use for "internal backflow
protective devices" and "fixture
outlet protection".
This 1989 edition was
prepared by Howard D.
Hendrickson, PE, vice president
of Water Service Consultants,
with assistance from Peter C.
Karalekas, Jr. of Region 1, EPA,
Boston.
This latest (2003) edition
has technical corrections
provided by Howard D.
Hendrickson, PE., showing
updates on pages iv, 18, 23, 30,
31, and 32.
CROSS-CONNECTION CONTROL MANUAL
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Contents
American Water Works Association Policy on Cross-Connections
Chapter
1. Purpose & Scope 1
2. Public Health Significance of Cross-Connections 2
3. Theory of Backflow and Backsiphonage 12
4. Methods and Devices for the Prevention of Backflow and
Backsiphonage 16
5. Testing Procedures for Backflow Preventers 25
6. Administration of a Cross-Connection Control Program 30
7. Cross-Connection Control Ordinance Provisions 33
Appendixes
A. Partial list of plumbing hazards 38
B. Illustrations of backsiphonage 38
C. Illustrations of backflow 40
D. Illustrations of air gaps 41
E. Illustrations of vacuum breakers 41
F. Glossary 42
G. Bibliography 43
H. Sample cross-connection survey form 44
I. Sample cross-connection test form 45
Illustrations
Human blood in the water system 2
Burned in the shower 3
Heating system anti-freeze into potable water 3
Salty drinks 4
Paraquat in the water system 4
Propane gas in the water mains 5
Chlordane and heptachlor at the Housing Authority 5
Boiler water enters high school drinking water 6
Pesticide in drinking water 6
Car wash water in the water main 7
Shipyard backflow contamination 7
Chlordane in the water main 8
Hexavalent chromium in drinking water 8
Employee health problems due to cross-connection 9
Dialysis machine contamination 10
Creosote in the water mains 11
Kool aid laced with chlordane 11
Figure
1 Pressure exerted by one foot of water at sea level ....
2 Pressure exerted by two feet of water at sea level ....
3 Pressure on the free surface of a liquid at sea level . . .
4 Effect of evacuating air from a column
5 Pressure relationships in a continuous fluid system at
the same elevation
6 Pressure relationships in a continuous fluid system at
different elevations
7 Backsiphonage in a plumbing system
8 Negative pressure created by constricted flow
9 Dynamically reduced pipe pressure(s)
... .12
...13
...13
...13
...13
...14
...14
... 14
.... 14
11 Valved connection between potable water and sanitary sewer 15
12 Air gap 16
13 Air gap in a piping system 16
14 Barometric loop 17
15 Atmospheric vacuum breaker 17
16 Atmospheric vacuum breaker typical installation 17
17 Atmospheric vacuum breaker in plumbing supply system 17
18 Hose bibb vacuum breaker 18
19 Typical installation of hose bibb vacuum breaker 18
20 Pressure vacuum breaker 18
21 Typical agricultural and industrial application of
pressure vacuum breaker 19
22 Double check valve with atmospheric vent 19
23 Residential use of double check with atmospheric vent 19
24 Double check valve 19
25 Double check valve detector check 20
26 Residential dual check 20
27 Residential installation 20
28 Copper horn 20
29a Reduced pressure zone backflow preventer 21
29b Reduced pressure zone backflow preventer 21
30 Reduced pressure zone backflow preventer principle of operation ... 22
31 Plating plant installation 22
32 Car wash installation 22
33 Typical by-pass configuration, reduced pressure principle devices ... 23
34 Typical installation, reduced pressure principle device,
horizontal illustration 23
3 5 Typical installation, reduced pressure principle device,
vertical installation 23
36 Typical installation, double check valve, horizontal and vertical
installation 24
37 Typical installation, residential dual check with straight
set and copper horn 24
38 Pressure vacuum breaker 26
39 Reduced pressure principle backflow preventer, Step 1 27
40 Reduced pressure principle backflow preventer, Step 2 27
41 Double check valve assemblies, Method 1 28
42 Double check valve assemblies, Method 2 29
43 Cross-connection protection, commercial, industrial and residential .30
44 Backsiphonage, Case 1 38
45 Backsiphonage, Case 2 38
46 Backsiphonage, Case 3 39
47 Backsiphonage, Case 4 39
48 Backsiphonage, Case 5 39
49 Backsiphonage, Case 6 39
50 Backflow Case 1 40
51 Backflow Case 2 40
52 Backflow Case 3 40
53 Backflow Case 4 40
54 Air gap to sewer subject to backpressure—force main 41
55 Air gap to sewer subject to backpressure—gravity drain 41
56 Fire system makeup tank for a dual water system 41
57 Vacuum breakers 41
58 Vacuum breaker arrangement for an outside hose hydrant 41
10 Valved connection between potable water and nonpotable fluid .... 15
TABLE OF CONTENTS
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AnAWWA
Statement of Policy
on Public Water Supply Matters.
Cross Connections
dopted by the Board of
Directors Jan. 26, 1970,
revised June 24, 1979, reaf-
firmed June 10, 1984 and
revised Jan. 28, 1990 and Jan.
21,2001.
The American Water
Works Association (AWWA)
recognizes water purveyors
have the responsibility to
supply potable water to their
customers. In the exercise of
this responsibility, water
purveyors or other respon-
sible authorities must
implement, administer, and
maintain ongoing backflow
prevention and cross-
connection control programs
to protect public water
systems from the hazards
originating on the premises
of their customers and from
temporary connections that
may impair or alter the water
in the public water systems.
The return of any water to
the public water system after
the water has been used for
any purpose on the
customer's premises or
within the customer's piping
system is unacceptable and
opposed by AWWA.
The water purveyor shall
assure that effective backflow
prevention measures commen-
surate with the degree of
hazard, are implemented to
ensure continual protection of
the water in the public water
distribution system. Customers,
together with other authorities
are responsible for preventing
contamination of the private
plumbing system under their
control and the associated
protection of the public water
system.
If appropriate back-flow
prevention measures have not
been taken, the water purveyor
shall take or cause to be taken
necessary measures to ensure
that the public water distribu-
tion system is protected from
any actual or potential
backflow hazard. Such action
would include the testing,
installation, and continual
assurance of proper operation
and installation of backflow -
prevention assemblies, devices,
and methods commensurate
with the degree of hazard at the
service connection or at the
point of cross connection or
both. If these actions are not
taken, water service shall
ultimately be eliminated.
To reduce the risk private
plumbing systems pose to the
public water distribution
system, the water purveyor's
backflow prevention program
should include public education
regarding the hazards backflow
presents to the safety of
drinking water and should
include coordination with the
cross connection efforts of local
authorities, particularly health
and plumbing officials. In areas
lacking a health or plumbing
enforcement agency, the water
purveyor should additionally
promote the health and safety
of private plumbing systems to
protect its customers from the
hazards of backflow.
CROSS-CONNECTION CONTROL MANUAL
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Chapter One
Purpose
and Scope
Kblic health officials have
)ng been concerned
about cross-connections and
backflow connections in
plumbing systems and in public
drinking water supply distribu-
tion systems. Such cross-
connections, which make
possible the contamination of
potable water, are ever-present
dangers. One example of what
can happen is an epidemic that
occurred in Chicago in 1933.
Old, defective, and improperly
designed plumbing and fixtures
permitted the contamination of
drinking water. As a result.
1,409 persons contracted
amebic dysentery; there were
98 deaths. This epidemic, and
others resulting from contami-
nation introduced into a water
supply through improper
plumbing, made clear the
responsibility of public health
officials and water purveyors for
exercising control over public
water distribution systems and
all plumbing systems connected
to them. This responsibility
includes advising and instruct-
ing plumbing installers in the
recognition and elimination of
cross-connections.
Cross-connections are the
links through which it is
possible for contaminating
materials to enter a potable
water supply. The contaminant
enters the potable water system
when the pressure of the
polluted source exceeds the
pressure of the potable source.
The action may be called
backsiphonage or backflow.
Essentially it is reversal of the
hydraulic gradient that can be
produced by a variety of
circumstances.
It might be assumed that
steps for detecting and elimi-
nating cross-connections would
be elementary and obvious.
Actually, cross-connections may
appear in many subtle forms
and in unsuspected places.
Reversal of pressure in the
water may be freakish and
unpredictable. The probability
of contamination of drinking
water through a cross-
connection occurring within a
single plumbing system may
seem remote; but, considering
the multitude of similar
systems, the probability is
great.
Why do such
cross-connections
exist?
First, plumbing is frequently
installed by persons who are
unaware of the inherent
dangers of cross-connections.
Second, such connections are
made as a simple matter of
convenience without regard to
the dangerous situation that
might be created. And, third,
they are made with reliance on
inadequate protection such as a
single valve or other mechanical
device.
To combat the dangers of
cross-connections and backflow
connections, education in their
recognition and prevention is
needed. First, plumbing
installers must know that
hydraulic and pollutional
factors may combine to produce
a sanitary hazard if a cross-
connection is present. Second,
they must realize that there are
available reliable and simple
standard backflow prevention
devices and methods that may
be substituted for the conve-
nient but dangerous direct
connection. And third, it should
be made clear to all that the
hazards resulting from direct
connections greatly outweigh
the convenience gained. This
manual does not describe all the
cross-connections possible in
piping systems. It does attempt
to reduce the subject to a
statement of the principles
involved and to make it clear to
the reader that such installa-
tions are potentially dangerous.
The primary purpose is to
define, describe, and illustrate
typical cross-connections and to
suggest simple methods and
devices by which they may be
eliminated without interfering
with the functions of plumbing
or water supply distribution
systems.
CHAPTER ONE • 1
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Chapter Two
Human Blood in
the Water System
Public Health
Significance of
Cross-Con nections
Kblic health officials have
ang been aware of the
impact that cross-connections
play as a threat to the public
health. Because plumbing
defects are so frequent and
the opportunity for contami-
nants to invade the public
drinking water through cross-
connections are so general,
enteric illnesses caused by
drinking water may occur at
most any location and at any
time.
The following documented
cases of cross-connection
problems illustrate and
emphasize how actual cross-
connections have compromised
the water quality and the public
health.
Health Department officials
cut off the water supply to
a funeral home located in a
large southern city, after it was
determined that human blood
had contaminated the fresh
water supply. City water and
plumbing officials said that they
did not think that the blood
contamination had spread
beyond the building, however,
inspectors were sent into the
neighborhood to check for
possible contamination. The
chief plumbing inspector had
received a telephone call
advising that blood was coming
from drinking fountains within
the building. Plumbing and
county health department
inspectors went to the scene
and found evidence that the
blood had been circulating in
the water system within the
building. They immediately
ordered the building cut off
from the water system at the
meter.
Investigation revealed that
the funeral home had been
using a hydraulic aspirator to
drain fluids from the bodies of
human "remains" as part of the
embalming process. The
aspirator directly connected to
the water supply system at a
faucet outlet located on a sink
in the "preparation" (embalm-
ing) room. Water flow through
the aspirator created suction
that was utilized to draw body
fluids through a hose and
needle attached to the suction
side of the aspirator.
The contamination of the
funeral home potable water
supply was caused by a combi-
nation of low water pressure in
conjunction with the simulta-
neous use of the aspirator.
Instead of the body fluids
flowing into the sanitary drain,
they were drawn in the opposite
direction—into the potable
water supply of the funeral
home!
Normal operation
Positive supply pressure Potable water
Closed
Negative supply pressure
Reverse flow through
aspirator due to
backsiphonage
CROSS-CONNECTION CONTROL MANUAL
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Burned in the
Shower
A resident of a small town in
Alabama, jumped in the
shower at 5 a.m. one morning
in October, 1986, and when he
got out his body was covered
with tiny blisters. "The more I
rubbed it, the worse it got," the
60 year old resident said. "It
looked like someone took a
blow torch and singed me."
He and several other
residents received medical
treatment at the emergency
room of the local hospital after
the water system was contami-
nated with sodium hydroxide, a
strong caustic solution.
Other residents claimed
that, "It (the water) bubbled up
and looked like Alka Seltzer. I
stuck my hand under the faucet
and some blisters came up."
Chemical bulk storage and holding tanks
One neighbor's head was
covered with blisters after she
washed her hair and others
complained of burned throats
or mouths after drinking the
water.
The incident began after an
8-inch water main, that fed the
town, broke and was repaired.
While repairing the water
main, one workman suffered
leg burns from a chemical in
the water and required medical
treatment. Measurements of the
ph of the water were as high as
13 in some sections of the pipe.
Investigation into the cause
of the problem led to a possible
source of the contamination
from a nearby chemical
company that distributes
chemicals such as sodium
hydroxide. The sodium hydrox-
ide is brought to the plant in
liquid form in bulk tanker
trucks and is transferred to a
holding tank and then pumped
into 55 gallon drums. When
the water main broke, a truck
driver was adding the water
from the bottom of the tank
truck instead of the top, and
sodium hydroxide back-
siphoned into the water main.
Water main
break and
repair
Heating System
Anti-Freeze into
Potable Water
Bangor Maine Water
Department employees
discovered poisonous antifreeze
in a homeowner's heating
system and water supply in
November, 1981. The incident
occurred when they shut off
'the service line to the home to
make repairs. With the flow of
water to the house cut off,
pressure in the lines in the
house dropped and the anti-
freeze, placed in the heating
system to prevent freeze-up of
an unused hot water heating
system, drained out of the
heating system into house
water lines, and flowed out to
the street. If it had not been
noticed, it would have entered
the homeowner's drinking
water when the water pressure
was restored.
added to boiler water
Water main
Curb stop with stop
and waste drain
Burned in the shower"
CHAPTER TWO
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Salty Drinks
Paraquat in the
Water System
In January, 1981, a nationally
known fast food restaurant
located in southeastern United
States, complained to the water
department that all their soft
drinks were being rejected by
their customers as tasting
"salty" This included soda
fountain beverages, coffee,
orange juice, etc. An investiga-
tion revealed that an adjacent
water customer complained of
salty water occurring simulta-
neously with the restaurant
incident. This second complaint
came from a water front ship
repair facility that was also
being served by the same water
main lateral. The (investigation
centered on the ship repair
facility and revealed the
following:
• A backflow preventer
that had been installed on the
service line to the shipyard had
frozen and had been replaced
with a spool piece sleeve.
• The shipyard fire
protection system utilized sea
water that was pumped by both
electric and diesel driven
pumps.
• The pumps were primed
by potable city water.
With the potable priming
line left open and the pumps
maintaining pressure in the fire
lines, raw salt water was
pumped through the priming
lines, through the spool sleeve
piece, to the ship repair facility
and the restaurant.
Backflow preventer
replaced by spool piece
Salt water suction line
for fire protection
( <~\7"ellow gushy stuff"
i poured from some of
the faucets in a small town in
Maryland, and the State of
Maryland placed a ban on
drinking the water supply.
Residents were warned not to
use the water for cooking,
bathing, drinking or any other
purpose except for flushing
toilets.
The incident drew wide-
spread attention and made the
local newspapers. In addition to
being the lead story on the
ABC news affiliate in Washing-
ton, D.C. and virtually all the
Washington/Baltimore news-
papers that evening. The news
media contended that lethal
pesticides may have contami-
nated the water supply and
among the contaminants was
paraquat, a powerful agricul-
tural herbicide.
The investigation disclosed
that the water pressure in the
town water mains was tempo-
rarily reduced due to a water
pump failure in the town water
supply pumping system.
Coincidentally, a gate valve
between a herbicide chemical
holding tank and the town
water supply piping had been
left open. A lethal cross-
connection had been created
that permitted the herbicide to
flow into the potable water
supply system. Upon restora-
tion of water pressure, the
herbicides flowed into the many
faucets and outlets on the town
water distribution system.
This cross-connection
created a needless and costly
event that fortunately did not
result in serious illness or loss of
life. Door-to-door public
notification, extensive flushing,
water sample analysis, emer-
gency arrangements to provide
temporary potable water from
tanker trucks, all contributed to
an expensive and unnecessary
town burden.
Recommended installation of
backflow preventer
CROSS-CONNECTION CONTROL MANUAL
-------
Propane Gas in the
Water Mains
Hose used for
propane tank
purging cross
connected
to private
fire hydrant
Recommended
backflow
Water main
pressure
65 psi
Hundreds of people were
evacuated from their
homes and businesses on an
August afternoon in a town in
Connecticut in 1982 as a result
of propane entering the city
water supply system. Fires were
reported in two homes and the
town water supply was con-
taminated. One five-room
residence was gutted by a blaze
resulting from propane gas
"bubbling and hissing" from a
bathroom toilet and in another
home a washing machine
explosion blew a woman
against a wall. Residents
throughout the area reported
hissing, bubbling noises,
coming from washing
machines, sinks and toilets.
Faucets sputtered out small
streams of water mixed with
gas and residents in the area
were asked to evacuate their
homes.
This near-disaster occurred
in one, 30,000 gallon capacity
liquid propane tank when the
gas company initiated immedi-
Explosion
ate repair procedures. To
start the repair, the tank was
"purged" of residual propane
by using water from one of two
private fire hydrants located on
the property. Water purging
is the preferred method of
purging over the use of carbon
dioxide since it is more positive
and will float out any sludge as
well as any gas vapors. The
"purging" consisted of hooking
up a hose to one of the private
fire hydrants located on the
property and initiating flushing
procedures.
Since the vapor pressure of
the propane residual in the tank
was 85 to 90 psi., and the water
pressure was only 65 to 70 psi.,
propane gas backpressure
backflowed into the water
main. It was estimated that the
gas flowed into the water mains
for about 20 minutes and that
about 2,000 cubic feet of gas
was involved. This was approxi-
mately enough gas to fill one
mile of an 8-inch water main.
Chlordane and
Heptachlor at the
Housing Authority
'~T~the services to seventy five
_L apartments housing
approximately three hundred
people were contaminated with
chlordane and heptachlor in a
city in Pennsylvania, in Decem-
ber, 1980. The insecticides
entered the water supply
system while an exterminating
company was applying them as
a preventative measure against
termites. While the pesticide
contractor was mixing the
chemicals in a tank truck with
water from a garden hose
coming from one of the
apartments, a workman was
cutting into a 6-inch main line
to install a gate valve. The end
of the garden hose was sub-
merged in the tank containing
the pesticides, and at the same
time, the water to the area was
shut off and the lines being
drained prior to the installation
of the gate valve. When the
workman cut the 6-inch line,
water started to drain out of the
cut, thereby setting up a
backsiphonage condition. As a
result, the chemicals were
siphoned out of the truck,
through the garden hose, and
into the system, contaminating
the seventy five apartments.
Repeated efforts to clean
and flush the lines were not
satisfactory and it was finally
decided to replace the water
line and all the plumbing that
was affected. There were no
reports of illness, but residents
of the housing authority were
told not to use any tap water
for any purpose and they were
given water that was trucked
into the area by volunteer fire
department personnel. They
were without their normal
water supply for 27 days.
Recommended installation
of hose bibb vacuum breaker
*!{ backflow preventer
\
CHAPTER TWO
-------
Boiler Water
Enters High School
Drinking Water
High School
Recommended installation
of backflow preventer ^ Leaky check valves
Toxic rust inhibitor and
defoamant containing
sodium dichromate
Street
A high school in New
Mexico, was closed for
several days in June 1984 when
a home economics teacher
noticed the water in the potable
system was yellow. Qty
chemists determined that
samples taken contained levels
of chromium as high as 700
parts per million, "astronomi-
cally higher than the accepted
levels of .05 parts per million."
The head chemist said that it
was miraculous that no one was
seriously injured or killed by the
high levels of chromium. The
chemical was identified as
sodium dichromate, a toxic
form of chromium used in
heating system boilers to inhibit
corrosion of the metal parts.
High school boilers
No students or faculty
were known to have consumed
any of the water; however, area
physicians and hospitals advised
that if anyone had consumed
those high levels of chromium,
the symptoms would be nausea,
diarrhea, and burning of the
mouth and throat. Fortunately,
the home economics teacher,
who first saw the discolored
water before school started,
immediately covered all water
fountains with towels so that
no one would drink the water.
Investigation disclosed
that chromium used in the
heating system boilers to inhibit
corrosion of metal parts entered
the potable water supply
system as a result of backflow
through leaking check valves
on the boiler feed lines.
Pesticide in
Drinking Water
A pesticide contaminated a
North Carolina water
system in April, 1986, prompt-
ing the town to warn residents
of 23 households not to drink
the water. The residents in the
affected area were supplied
drinking water from a tank
truck parked in the parking lot
of a downtown office building
until the condition could be
cleared up. Residents com-
plained of foul smelling water
but there were no reports of
illness from ingesting the water
that had been contaminated
with a pesticide containing
chlordane and heptachlor.
Authorities stated that the
problem occurred when a water
main broke at the same time
that a pest control service was
filling a pesticide truck with
water. The reduction in pressure
caused the pesticide from inside
the tank to be sucked into the
building's water main. The
pesticide contaminated the
potable water supply of the
office building and neighbor-
hood area.
Car Wash Water
in the Water Main
Street
Tiis car wash cross-
connection and back-
pressure incident, which
occurred in February, 1979,
in the state of Washington,
resulted in backflow chemical
contamination of approximately
100 square blocks of water
mains. Prompt response by the
water department prevented a
potentially hazardous water
quality degradation problem
without a recorded case of
illness.
Numerous complaints of
grey-green and "slippery" water
were received by the water
department coming from the
same general area of town. A
sample brought to the water
department by a customer
confirmed the reported problem
and preliminary analysis
indicated contamination with
what appeared to be a deter-
gent solution. While emergency
crews initiated flushing opera-
tions, further investigation
within the contaminated area
signaled the problem was
probably caused by a car wash,
Recommended installation
of hose bibb vacuum breaker
backflow preventer
CROSS-CONNECTION CONTROL MANUAL
-------
or laundry, based upon the
soapy nature of the contami-
nant. The source was quickly
narrowed down to a car wash
and the proprietor was ex-
tremely cooperative in admit-
ting to the problem and
explaining how it had occurred.
The circumstances leading up
to the incident were as follows:
• On Saturday, February
10, 1979, a high pressure pump
broke down at the car wash.
This pump recycled reclaimed
wash and rinse water and
pumped it to the initial
scrubbers of the car wash. No
potable plumbing connection
is normally made to the car
wash's scrubber system.
• After the pump broke
down, the car wash owner
was able to continue operation
by connecting a 2-inch hose
section temporarily between the
potable supply within the car
wash, and the scrubber cycle
piping.
• On Monday, February
12, 1979, the owner repaired
the high pressure pump and
resumed normal car wash
operations. The 2-inch hose
connection (cross-connection)
was not removed!
• Because of the cross-
connection, the newly repaired
high pressure pump promptly
pumped a large quantity of
the reclaimed wash/rinse water
out of the car wash and into a
12-inch water main in the
street. This in turn was deliv-
ered to the many residences
and commercial establishments
connected to the water main.
Within 24 hours of the
incident, the owner of the car
wash had installed a 2-inch
reduced pressure principle
backflow preventer on his
water service and all car wash
establishments in Seattle that
used a wash water reclaim
system were notified of the
state requirement for backflow
prevention.
Wax injectors
Soap injectors
Shipyard
Backflow
Contamination
Shipboard
raw water
pumping
system
Cafeteria drinking fountains
and sanitation water
* Reduced pressure principle backflow
preventers should have been installed
at dockside outlets and other locations
Recirculating
pump
Reclaim tanks
backflow preventer
To restrooms
Water fountains at an East
Coast Shipyard were
posted "No Drinking" as
workers flushed the water lines
to eliminate raw river water
that had entered the shipyard
following contamination from
incorrectly connected water
lines between ships at the pier
and the shipyard. Some third
shift employees drank the
water before the pollution
was discovered and later
complained of stomach cramps
and diarrhea.
The cause of the problem
was a direct cross-connection
between the on-board salt
water fire protection water
system and the fresh water
connected to one of the ships at
the dock. While the shipyard
had been aware of the need
for backflow protection at the
dockside tie up area, the device
had not been delivered and
installed prior to the time of the
incident. As a result, the salt
water on-board fire protection
system, being at a greater
pressure than the potable
supply, forced the salt water,
through backpressure, into the
shipyard potable supply.
Fortunately, a small
demand for potable water at
the time of the incident
prevented widespread pollution
in the shipyard and the sur-
rounding areas.
Potable
water supply
CHAPTER TWO
-------
Chlordane in the
Water Main
Tn October, 1979, approxi-
JLmately three gallons of
chlordane, a highly toxic
insecticide, was sucked back
(back-siphoned) into the water
system of a residential area of
a good sized eastern city.
Residents complained that the
water "looked milky, felt greasy,
foamed and smelled," and as
one woman put it, "It was
similar to a combination of
kerosene and Black Flag
pesticide."
The problem developed
while water department
personnel were repairing a
water main. A professional
exterminator, meanwhile, was
treating a nearby home with
chlordane for termite elimina-
tion. The workman for the
exterminator company left one
end of a garden hose that was
connected to an outside hose
bibb tap in a barrel of diluted
pesticide. During the water
service interruption, the
chlordane solution was back-
siphoned from the barrel
through the house and into the
water mains.
Following numerous
complaints, the water depart-
ment undertook an extensive
program of flushing of the
water mains and hand delivered
letters telling residents to flush
their lines for four hours before
using the water. Until the water
lines were clear of the contami-
nant, water was hand-hauled
into homes, and people went
out of their homes for showers,
meals and every other activity
involving potable water.
Fortunately, due to the obvious
bad taste, odor and color of the
contaminated water, no one
consumed a sufficient quantity
to endanger health.
Hexavalent
Chromium in
Drinking Water
In July, 1982, a well meaning
maintenance mechanic, in
attempting to correct a fogging
lens in an overcooled laser
machine, installed a tempering
valve in the laser cooling line,
and inadvertently set the stage
for a backpressure backflow
incident that resulted in
hexavalent chromium contami-
nating the potable water of a
large electronic manufacturing
company in Massachusetts
employing 9,000 people.
Quantities of 50 parts per
million hexavalent chromium
were found in the drinking
water which is sufficient to
cause severe vomiting, diarrhea,
Hexavalent
chromium
added to
chilled water
and intestinal sickness.
Maintenance crews working
during the plant shutdown
were able to eliminate the cross-
connection and thoroughly
flush the potable water system,
thereby preventing a serious
health hazard from occurring.
The incident occurred as
follows:
• Laser machine lenses
were kept cool by circulating
chilled water that came from a
large refrigeration chiller. The
water used in the chiller was
treated with hexavalent
chromium, a chemical additive
used as an anticorrosive agent
and an algicide. As a result, the
chilled water presented a toxic,
non-potable substance unfit for
human consumption but very
Temporary
chiller
feed pump J
Hot water
heater
Recommended installation of
backflow preventer —.
/'To plant vending machines
Recommended installation of hose bibb
vacuum breaker backflow preventer
8 • CROSS-CONNECTION CONTROL MANUAL
-------
acceptable for industrial process
water. No health hazard was
present as long as the piping
was identified, kept separate
from potable drinking water
lines, and not cross-connected
to the potable water supply.
• A maintenance
mechanic correctly reasoned
that by adding a tempering
valve to the chilled water line,
he could heat up the water a bit
and eliminate fogging of the
laser lenses resulting from the
chilled water being too cold.
The problem with the installa-
tion of the tempering valve was
that a direct cross-connection
had been inadvertently made
between the toxic chilled water
and the potable drinking water
line!
• Periodic maintenance
to the chiller system was
performed in the summer,
requiring that an alternate
chiller feed pump be tempo-
rarily installed. This replace-
ment pump had an outlet
pressure of 150 psi, and
promptly established an
imbalance of pressure at the
tempering valve, thereby over-
pressurizing the 60 psi, potable
supply. Backpressure backflow
resulted and pushed the toxic
chilled water from the water
heater and then into the plant's
potable drinking water supply.
"Yellowish green water started
pouring out of the drinking
fountains, the washroom, and
all potable outlets.
Employee Health
Problems due to
Cross-Connection
A cross-connection incident
occurring in a modern
seven-story office building
located in a large city in New
Hampshire, in March, 1980,
resulted in numerous cases of
nausea, diarrhea, loss of time
and employee complaints as to
the poor quality of the water.
On Saturday, March 1,
1980, a large fire occurred two
blocks away from a seven-story
office building in this large
New Hampshire city. On
Sunday, March 2, 1980, the
maintenance crew of the office
building arrived to perform the
weekly cleaning, and after
drinking the water from the
drinking fountains, and
sampling the coffee from the
coffee machines, noticed that
the water smelled rubbery and
had a strong bitter taste. Upon
notifying the Manchester Water
Company, water samples were
taken and preliminary analysis
disclosed that the contaminants
found were not the typical
contaminants associated with
fire line disturbances. Investi-
gating teams suspected that
either the nearby fire could
have siphoned contaminants
from adjacent buildings into the
water mains, or the contamina-
tion could have been caused by
a plumbing deficiency occurring
within the seven story building
itself.
Water ph levels of the
building water indicated that
an injection of chemicals had
probably taken place within the
seven-story building. Tracing of
the water lines within the
building pinpointed a 10,000
gallon hot-water storage tank
that was used for heat storage
in the solar heating system. It
did not have any backflow
protection on the make-up
supply line! As the storage tank
pressure increased above the
supply pressure, as a result of
thermal expansion, the poten-
tial for backpressure backflow
was present. Normally, this
would not occur because a
boost pump in the supply line
would keep the supply pressure
to the storage tank always
greater than the highest tank
pressure. The addition of rust
inhibiting chemicals to this
tank greatly increased the
degree of hazard of the liquid.
Unfortunately, at the same time
that the fire took place, the
pressure in the water mains was
reduced to a dangerously low
pressure and the low pressure
cutoff switches simultaneously
shut off the storage tank
booster pumps. This combina-
tion allowed the boiler water,
together with its chemical
contaminants, the opportunity
to enter the potable water
supply within the building.
When normal pressure was
reestablished in the water
mains, the booster pumps
kicked in, and the contami-
nated water was delivered
throughout the building.
Roof mounted solar panels
Water i
main
Recommended installation
of backflow preventers
Backpressure
backflow
CHAPTER TWO
-------
Dialysis Machine
Contamination
Creosote in the
Water Mains
Ethylene glycol, an anti-
freeze additive to air
conditioning cooling tower
water, inadvertently entered the
potable water supply system in
a medical center in Illinois in
September, 1982, and two of
six dialysis patients succumbed
as a direct or indirect result of
the contamination.
The glycol was added to
the air conditioning water, and
the glycol/water mix was stored
in a holding tank that was an
integral part of the medical
center's air conditioning cooling
system. Pressurized make-up
water to the holding tank was
supplied by a medical center
Air conditioning units
potable supply line and fed
through a manually operated
control valve. With this valve
open, or partially open, potable
make-up water flowed slowly
into the glycol/water mixture in
the holding tank until it filled
to the point where the pressure
in the closed tank equaled the
pressure in the potable water
supply feed line. As long as the
potable feed line pressure was at
least equal to, or greater than,
the holding tank pressure, no
backflow could occur. The stage
was set for disaster, however.
It was theorized that
someone in the medical center
flushed a toilet or turned on a
Glycol/water
pressurized
holding tank
Submerged inlet
cross-connection
Slightly
open
manual
valve
Recommneded installation
of backflow preventer
faucet, which in turn dropped
the pressure in the potable
supply line to the air condition-
ing holding tank. Since the
manually operated fill valve was
partially open, this allowed the
glycol/water mixture to enter
the medical center potable
pipelines and flow into the
dialysis equipment. The dialysis
filtration system takes out trace
chemicals such as those used in
the city water treatment plant,
but the system could not
handle the heavy load of
chemicals that it was suddenly
subjected to.
The effect upon the dialysis
patients was dramatic: patients
became drowsy, confused and
fell unconscious, and were
promptly removed to intensive
care where blood samples were
taken. The blood samples
revealed a build-up of acid and
the medical director stated that,
"Something has happened in
dialysis." Dialysis was repeated
on the patients a second and
third time.
Tests of the water supply to
the filtration system quickly
determined the presence of "an
undesirable chemical in the
water purification system." The
partially open fill valve was
then found that it had permit-
ted the glycol water mix to
drain from the air conditioning
holding tank into the medical
center's potable supply lines
and then into the dialysis
filtration system equipment.
Backpressure backflow
Main water
supply
Cosote entered the water
[istribution system of a
southeastern county water
authority in Georgia, in
November, 1984, as a result of
cross-connection between a
%-inch hose that was being
used as a priming line between
a fire service connection and the
suction side of a creosote pump.
The hose continually supplied
water to the pump to ensure
the pump was primed at all
times. However, while repairs
were being made to a private
fire hydrant, the creosote back-
siphoned into the water mains
and contaminated a section of
the water distribution system.
Detailed investigation of
the cause of the incident
disclosed that the wood
preservative company, as part of
their operation, pumped
creosote from collective pits to
other parts of their operation.
The creosote pump would
automatically shut off when the
creosote in the pit was lowered
to a predetermined level. After
the creosote returned to a
higher level, the pump would
restart. This pump would lose
its prime quite often prior to
the pit refilling, and to prevent
the loss of prime, the wood
preservative company would
connect a hose from a %-inch
hose bibb, located on the fire
service line, to the suction side
of the pump. The hose bibb
remained open at all times in an
effort to continuously keep the
pump primed.
Recommended installation
of backflow preventer
10 • CROSS-CONNECTION CONTROL MANUAL
-------
Kool-Aid Laced
With Chlordane
Street main Private shut-off (7^ Recommended installation
/ /} of backflow preventers
Creosote pump Process ~
water
Recommended installation /..
of backflow preventers
Creosote
contaminated flow
Repairs were necessary to
one of the private fire hydrants
on the wood preservative
company property, necessitating
the shutting down of one of two
service lines and removal of the
damaged fire hydrant for repair.
Since the hydrant was at a
significantly lower level than
the creosote pit, the creosote
back-siphoned through a %-
inch pump priming hose
connecting the creosote pit to
the fire service line.
After the repairs were
made to the hydrant, and the
water service restored, the
creosote, now in the fire lines,
was forced into the main water
distribution system.
In August, 1978, a profes-
sional exterminator was
treating a church located in a
small town in South Carolina,
for termite and pest control.
The highly toxic insecticide
chlordane was being mixed
with water in small buckets,
and garden hoses were left
submerged in the buckets while
the mixing was being accom-
plished. At the same time,
water department personnel
came by to disconnect the
parsonage's water line from the
church to install a separate
water meter for the parsonage.
In the process, the water was
shut off in the area of the
church building. Since the
church was located on a steep
hill, and as the remaining water
in the lines was used by
residents in the area, the church
was among the first places to
experience a negative pressure.
The chlordane was quickly
siphoned into the water lines
within the church and became
mixed with the Kool-Aid being
prepared by women for the
vacation bible school. Approxi-
mately a dozen children and
three adults experienced
dizziness and nausea. Fortu-
nately, none required hospital-
ization or medical attention.
Recommended installation
of hose bibb vacuum
breaker backflow preventer
CHAPTER TWO • 11
-------
Chapter Three
Theory of Backflow
and Backsiphonage
A cross-connection1 is the
link or channel connecting
a source of pollution with a
potable water supply. The
polluting substance, in most
cases a liquid, tends to enter the
potable supply if the net force
acting upon the liquid acts in
the direction of the potable
supply. Two factors are therefore
essential for backflow. First,
there must be a link between
the two systems. Second, the
resultant force must be toward
the potable supply.
An understanding of the
principles of backflow and
backsiphonage requires an
understanding of the terms
frequently used in their
discussion. Force, unless com-
pletely resisted, will produce
motion. Weight is a type of
force resulting from the earth's
gravitational attraction.
Pressure (P) is a force-per-unit
area, such as pounds per square
inch (psi). Atmospheric pressure is
the pressure exerted by the
weight of the atmosphere above
the earth.
Pressure may be referred to
using an absolute scale, pounds
per square inch absolute (psia),
or gage scale, pounds per
square inch gage (psig).
Absolute pressure and gage
pressure are related. Absolute
pressure is equal to the gage
pressure plus the atmospheric
pressure. At sea level the
atmospheric pressure is 14.7
psia. Thus,
p = p -1-1
*- absolute *- gage ' ^
or
Pgage = Pabsolute ~ 14.7 pSl
In essence then, absolute
pressure is the total pressure.
Gage pressure is simply the
pressure read on a gage. If there
is no pressure on the gage other
than atmospheric, the gage
would read zero. Then the
absolute pressure would be
equal to 14.7 psi which is the
atmospheric pressure.
The term vacuum indicates
that the absolute pressure is less
than the atmospheric pressure
and that the gage pressure is
negative. A complete or total
vacuum would mean a pressure
of 0 psia or -14.7 psig. Since it
is impossible to produce a total
vacuum, the term vacuum, as
used in the text, will mean all
degrees of partial vacuum. In a
partial vacuum, the pressure
would range from slightly less
than 14.7 psia (0 psig) to
slightly greater than 0 psia
(-14.7 psig).
Backsiphonage1 results in
fluid flow in an undesirable or
reverse direction. It is caused by
atmospheric pressure exerted on
a pollutant liquid forcing it
toward a potable water supply
system that is under a vacuum.
Backflow, although literally
meaning any type of reversed
flow, refers to the flow produced
by the differential pressure
existing between two systems
both of which are at pressures
greater than atmospheric.
Water Pressure
For an understanding of the
nature of pressure and its
relationship to water depth,
consider the pressure exerted on
the base of a cubic foot of water
at sea level. (See Fig. 1) The
average weight of a cubic foot
of water is 62.4 pounds per
square foot gage. The base may
be subdivided into 144-square
inches with each subdivision
being subjected to a pressure of
0.433 psig.
Suppose another cubic foot
of water were placed directly
on top of the first (See Fig. 2).
The pressure on the top surface
of the first cube which was
originally atmospheric, or
0 psig, would now be 0.433
psig as a result of the super-
imposed cubic foot of water.
The pressure of the base of
the first cube would also be
increased by the same amount
of 0.866 psig, or two times the
original pressure.
FIGURE 1.
Pressure exerted by 1 foot of
water at sea level.
i
/
12"-
/•
62.4#/f
^-
'/////
'//?//,>
Y'
/12"
/
'/// ^
W^
I
^
0.433 psig
1See formal definition in the glossary of
the appendix
12 • CROSS-CONNECTION CONTROL MANUAL
-------
If this process were
repeated with a third cubic foot
of water, the pressures at the
base of each cube would be
1,299 psig, 0.866 psig, and
0.433 psig, respectively. It is
evident that pressure varies
with depth below a free water
surface; in general each foot of
elevation change, within a
liquid, changes the pressure by
an amount equal to the weight-
per-unit area of 1 foot of the
liquid. The rate of increase for
water is 0.433 psi per foot of
depth.
Frequently water pressure
is referred to using the terms
"pressure head" or just "head,"
and is expressed in units of feet
of water. One foot of head
would be equivalent to the
pressure produced at the base
of a column of water 1 foot in
depth. One foot of head or
1 foot of water is equal to 0.433
psig. One hundred feet of head
is equal to 43.3 psig.
Siphon Theory
Figure 3 depicts the atmo-
spheric pressure on a water
surface at sea level. An open
tube is inserted vertically into
the water; atmospheric pres-
sure, which is 14.7 psia, acts
equally on the surface of the
water within the tube and on
the outside of the tube.
FIGURES.
Pressure on the free surface of a
liquid at sea level.
14. 7 psia
sea level
/•
/%
/I
^
14.7
psia
level exactly balances the
weight of a column of water
33.9 feet in height. The
absolute pressure within the
column of water in Figure 4 at
a height of 11.5 feet is equal to
9-7 psia. This is a partial
vacuum with an equivalent
gage pressure of-5.0 psig.
As a practical example,
assume the water pressure at a
closed faucet on the top of a
100-foot high building to be 20
psig; the pressure on the
ground floor would then be
63.3 psig. If the pressure at the
ground were to drop suddenly
due to a heavy fire demand in
the area to 33.3 psig, the
pressure at the top would be
reduced to -10 psig. If the
building water system were
airtight, the water would
remain at the level of the faucet
FIGURE 4.
Effect of evacuating air from a
column.
because of the partial vacuum
created by the drop in pressure.
If the faucet were opened,
however, the vacuum would be
broken and the water level
would drop to a height of 77
feet above the ground. Thus,
the atmosphere was supporting
a column of water 23 feet high.
Figure 5 is a diagram of an
inverted U-tube that has been
filled with water and placed in
two open containers at sea level.
If the open containers are
placed so that the liquid levels
in each container are at the
same height, a static state will
exist; and the pressure at any
specified level in either leg of
the U-tube will be the same.
The equilibrium condition
is altered by raising one of the
containers so that the liquid
level in one container is 5 feet
FIGURE 5.
Pressure relationships in a
continuous fluid system at the
same elevation.
FIGURE 2.
Pressure exerted by 2 feet of
water at sea level.
0.433 psig
0.866 psig
24"
1See formal definition in the glossary of
the appendix
If, as shown in Figure 4,
the tube is slightly capped and
a vacuum pump is used to
evacuate all the air from the
sealed tube, a vacuum with a
pressure of 0 psia is created
within the tube. Because the
pressure at any point in a static
fluid is dependent upon the
height of that point above a
reference line, such as sea level,
it follows that the pressure
within the tube at sea level
must still be 14.7 psia. This is
equivalent to the pressure at the
base of a column of water 33.9
feet high and with the column
open at the base, water would
rise to fill the column to a depth
of 33.9 feet. In other words, the
weight of the atmosphere at sea
"Zero" Absolute
Pressure
a
^
oi
CO
t
LO
I
Sea level
0.0
psia
or
-14.7
psig
9.7
psia
14.7
psia
:^u
SQ
Vacui
or -5.0 psig
14.7 psia or
0.0 psig
14.7
psia
10.3 psia
4.7 psia
14.7
psia
CHAPTER THREE
13
-------
above the level of the other. (See
Fig. 6.) Since both containers
are open to the atmosphere, the
pressure on the liquid surfaces
in each container will remain at
14.7 psia.
If it is assumed that a static
state exists, momentarily,
within the system shown in
Figure 6, the pressure in the left
tube at any height above the
free surface in the left container
can be calculated. The pressure
at the corresponding level in the
right tube above the free surface
in the right container may also
be calculated.
As shown in Figure 6, the
pressure at all levels in the left
tube would be less than at
corresponding levels in the right
tube. In this case, a static
condition cannot exist because
fluid will flow from the higher
pressure to the lower pressure;
the flow would be from the
right tank to the left tank. This
arrangement will be recognized
as a siphon. The crest of a
siphon cannot be higher than
33.9 feet above the upper liquid
FIGURE 6.
Pressure relationships in a
continuous fluid system at
different elevations.
8.2 psia
10.3 psia
level, since atmosphere cannot
support a column of water
greater in height than 33.9 feet.
Figure 7 illustrates how
this siphon principle can be
hazardous in a plumbing
system. If the supply valve is
closed, the pressure in the line
supplying the faucet is less than
the pressure in the supply line
to the bathtub. Flow will occur,
therefore, through siphonage,
from the bathtub to the open
faucet.
FIGURE 7.
Backsiphonage in a plumbing
system.
Valve open
E
Submerged inlet
Valve open
Closed supply
The siphon actions cited
have been produced by reduced
pressures resulting from a
difference in the water levels at
two separated points within a
continuous fluid system.
Reduced pressure may also
be created within a fluid system
as a result of fluid motion. One
of the basic principles of fluid
mechanics is the principle of
conservation of energy. Based
upon this principle, it may be
shown that as a fluid acceler-
ates, as shown in Figure 8, the
pressure is reduced. As water
flows through a constriction
such as a converging section of
pipe, the velocity of the water
increases; as a result, the
pressure is reduced. Under such
conditions, negative pressures
may be developed in a pipe.
The simple aspirator is based
upon this principle. If this
point of reduced pressure is
linked to a source of pollution,
backsiphonage of the pollutant
can occur.
FIGURE 8.
Negative pressure created by
constricted flow.
+30 psig
+30 psig
One of the common
occurrences of dynamically
reduced pipe pressures is found
on the suction side of a pump.
In many cases similar to the one
illustrated in Figure 9, the line
supplying the booster pump is
undersized or does not have
sufficient pressure to deliver
water at the rate at which the
pump normally operates. The
rate of flow in the pipe may be
increased by a further reduction
in pressure at the pump intake.
This often results in the creation
of negative pressure at the
pump intake. This often results
in the creation of negative
pressure. This negative pressure
may become low enough in
some cases to cause vaporization
of the water in the line. Actu-
ally, in the illustration shown,
FIGURE 9.
Dynamically reduced pipe
pressures.
From pollution To fixture
source
Booster pump
flow from the source of pollu-
tion would occur when pressure
on the suction side of the pump
is less than pressure of the
pollution source; but this is
backflaw, which will be discussed
below.
The preceding discussion
has described some of the
means by which negative
pressures may be created and
which frequently occur to
produce backsiphonage. In
addition to the negative
pressure or reversed force
necessary to cause
backsiphonage and backflow,
there must also be the cross-
connection or connecting link
between the potable water
supply and the source of
pollution. Two basic types of
connections may be created in
piping systems. These are the
solid pipe with valved connec-
tion and the.
14 • CROSS-CONNECTION CONTROL MANUAL
-------
Figures 10 and 11 illustrate
solid connections. This type of
connection is often installed
where it is necessary to supply
an auxiliary piping system from
the potable source. It is a direct
connection of one pipe to
another pipe or receptacle.
Solid pipe connections are
often made to continuous or
intermittent waste lines where
it is assumed that the flow will
be in one direction only. An
example of this would be used
cooling water from a water
jacket or condenser as shown in
Figure 11. This type of connec-
tion is usually detectable but
creating a concern on the part
FIGURE 10.
Valved connections between
potable water and nonpotable
fluid.
Non potable
Potable
FIGURE 11
Valved connection between
potable water and sanitary sewer.
of the installer about the
possibility of reversed flow is
often more difficult. Upon
questioning, however, many
installers will agree that the
solid connection was made
because the sewer is occasion-
ally subjected to backpressure.
Submerged inlets are found
on many common plumbing
fixtures and are sometimes
necessary features of the fixtures
if they are to function properly.
Examples of this type of design
are siphon-jet urinals or water
closets, flushing rim slop sinks,
and dental cuspidors. Oldstyle
bathtubs and lavatories had
supply inlets below the flood
level rims, but modern sanitary
design has minimized or
eliminated this hazard in new
fixtures. Chemical and indus-
trial process vats sometimes
have submerged inlets where
the water pressure is used as an
aid in diffusion, dispersion and
agitation of the vat contents.
Even though the supply pipe
may come from the floor above
the vat, backsiphonage can
occur as it has been shown that
the siphon action can raise a
liquid such as water almost 34
feet. Some submerged inlets
City supply
Condenser
(c
difficult to control are those
which are not apparent until a
significant change in water level
occurs or where a supply may
be conveniently extended below
the liquid surface by means of a
hose or auxiliary piping. A
submerged inlet may be created
in numerous ways, and its
detection in some of these
subtle forms may be difficult.
The illustrations included
in part B of the appendix are
intended to describe typical
examples of backsiphonage,
showing in each case the nature
of the link or cross-connection,
and the cause of the negative
pressure.
Backflow
Backflow1, as described in this
manual, refers to reversed flow
due to backpressure other than
siphonic action. Any intercon-
nected fluid systems in which
the pressure of one exceeds the
pressure of the other may have
flow from one to the other as a
result of the pressure differen-
tial. The flow will occur from
the zone of higher pressure to
the zone of lower pressure. This
type of backflow is of concern in
buildings where two or more
piping systems are maintained.
The potable water supply is
usually under pressure directly
from the city water main.
Occasionally, a booster pump is
used. The auxiliary system is
often pressurized by a centrifical
pump, although backpressure
may be caused by gas or steam
pressure from a boiler. A
reversal in differential pressure
may occur when pressure in the
potable system drops, for some
reason, to a pressure lower than
that in the system to which the
potable water is connected.
The most positive method
of avoiding this type of
backflow is the total or com-
plete separation of the two
systems. Other methods used
involve the installation of
mechanical devices. All meth-
ods require routine inspection
and maintenance.
Dual piping systems are
often installed for extra protec-
tion in the event of an emer-
gency or possible mechanical
failure of one of the systems.
Fire protection systems are an
example. Another example is
the use of dual water connec-
tions to boilers. These installa-
tions are sometimes inter-
connected, thus creating a
health hazard.
The illustrations in part C
of the appendix depict installa-
tions where backflow under
pressure can occur, describing
the cross-connection and the
cause of the reversed flow.
Sanitary sewer
1See formal definition in the glossary of
the appendix
CHAPTER THREE • 15
-------
Chapter Four
Methods and Devices
for the Prevention of
Backflow and
Back-Si phonage
A wide choice of devices
exists that can be used to
prevent backsiphonage and
backpressure from adding
contaminated fluids or gases
into a potable water supply
system. Generally, the selection
of the proper device to use is
based upon the degree of hazard
posed by the cross-connection.
Additional considerations are
based upon piping size, location,
and the potential need to
periodically test the devices to
insure proper operation.
There are six basic types of
devices that can be used to
correct cross-connections: air
gaps, barometric loops, vacuum
breakers—both atmospheric
and pressure type, double check
with intermediate atmospheric
vent, double check valve
assemblies, and reduced pressure
principle devices. In general, all
manufacturers of these devices,
with the exception of the
barometric loop, produce them
to one or more of three basic
standards, thus insuring the
public that dependable devices
are being utilized and marketed.
The major standards in the
industry are: American Society
of Sanitary Engineers ASSE),
American Water Works Associa-
tion (AWWA), and the Univer-
sity of California Foundation for
Cross-Connection Control and
Hydraulic Research.
Air Gap
Air gaps are non-mechanical
backflow preventers that are
very effective devices to be used
where either backsiphonage or
backpressure conditions may
exist. Their use is as old as
piping and plumbing itself, but
only relatively recently have
standards been issued that
standardize their design. In
general, the air gap must be
twice the supply pipe diameter
but never less than one inch.
See Figure 12.
FIGURE 12.
Air gap.
Diameter
"D" -
An air gap, although an
extremely effective backflow
preventer when used to prevent
backsiphonage and backpres-
sure conditions, does interrupt
the piping flow with corre-
sponding loss of pressure for
subsequent use. Consequently,
air gaps are primarily used at
end of the line service where
reservoirs or storage tanks are
desired. When contemplating
the use of an air gap, some
other considerations are:
(1) In a continuous piping
system, each air gap requires
the added expense of reservoirs
and secondary pumping
systems.
(2) The air gap may be easily
defeated in the event that the
"2D" requirement was purposely
or inadvertently compromised.
Excessive splash may be encoun-
tered in the event that higher
than anticipated pressures or
flows occur. The splash may be a
cosmetic or true potential
hazard—the simple solution
being to reduce the "2D"
dimension by thrusting the
supply pipe into the receiving
funnel. By so doing, the air gap
is defeated.
(3) At an air gap, we expose the
water to the surrounding air
with its inherent bacteria, dust
particles, and other airborne
pollutants or contaminants. In
addition, the aspiration effect of
the flowing water can drag down
surrounding pollutants into the
reservoir or holding tank.
(4) Free chlorine can come out of
treated water as a result of the air
gap and the resulting splash and
churning effect as the water
enters the holding tanks. This
reduces the ability of the water
to withstand bacteria contamina-
tion during long term storage.
(5) For the above reasons, air
gaps must be inspected as
frequently as mechanical
backflow preventers. They are
not exempt from an in-depth
cross-connection control pro-
gram requiring periodic inspec-
tion of all backflow devices.
Air gaps may be fabricated
from commercially available
plumbing components or
purchased as separate units and
integrated into plumbing and
piping systems. An example of
the use of an air gap is shown in
Figure 13.
16 • CROSS-CONNECTION CONTROL MANUAL
-------
FIGURE 13.
Air gap in a piping system.
Supply piping
r
i
l
7777777^,
jt
-Td
Tank or reservoir
Barometric Loop
The barometric loop consists of
a continuous section of supply
piping that abruptly rises to a
height of approximately 35 feet
and then returns back down to
the originating level. It is a loop
in the piping system that
effectively protects against
backsiphonage. It may not be
used to protect against back-
pressure.
Its operation, in the
protection against back-
siphonage, is based upon the
principle that a water column,
at sea level pressure, will not
rise above 33.9 feet (Ref.
Chapter 3, Fig. 4 Page 13).
In general, barometric
loops are locally fabricated, and
are 35 feet high.
FIGURE 14.
Barometric loop.
Atmospheric Vacuum
Breaker
These devices are among the
simplest and least expensive
mechanical types of backflow
preventers and, when installed
properly, can provide excellent
protection against back-
siphonage. They must not be
utilized to protect against
backpressure conditions.
Construction consists usually of
a polyethylene float which is
free to travel on a shaft and seal
in the uppermost position
against atmosphere with an
elastomeric disc. Water flow
lifts the float, which then causes
the disc to seal. Water pressure
keeps the float in the upward
sealed position. Termination of
the water supply will cause the
disc to drop down venting the
unit to atmosphere and thereby
opening downstream piping to
atmospheric pressure, thus
preventing backsiphonage.
Figure 15 shows a typical
atmospheric breaker.
In general, these devices
are available in V^-inch through
3-inch size and must be
installed vertically, must not
have shutoffs downstream,
and must be installed at least
6-inches higher than the final
outlet. They cannot be tested
once they are installed in the
plumbing system, but are, for
the most part, dependable,
trouble-free devices for
backsiphonage protection.
FIGURE 15.
Atmospheric vacuum breaker.
FIGURE 16.
Atmospheric vacuum breaker
typical installation.
FIGURE 17.
Atmospheric vacuum breaker in
plumbing supply system.
Non flow condition
Figure 16 shows the
generally accepted installation
requirements—note that no
shutoff valve is downstream
of the device that would
otherwise keep the atmospheric
vacuum breaker under constant
pressure.
Figure 17 shows a typical
installation of an atmospheric
vacuum breaker in a plumbing
supply system.
CHAPTER FOUR • 17
-------
Hose Bibb
Vacuum Breakers
These small devices are a
specialized application of the
atmospheric vacuum breaker.
They are generally attached to
sill cocks and in turn are
connected to hose supplied
outlets such as garden hoses,
slop sink hoses, spray outlets,
etc. They consist of a spring
loaded check valve that seals
against an atmospheric outlet
when water supply pressure is
turned on. Typical construction
is shown in Figure 18.
When the water supply is
turned off, the device vents to
atmosphere, thus protecting
against backsiphonage condi-
tions. They should not be used
as backpressure devices. Manual
drain options are available,
together with tamper-proof
versions. A typical installation is
shown in Figure 19-
FIGURE 18.
Hose bibb vacuum breaker.
FIGURE 19.
Typical installation of hose bibb
vacuum breaker.
Pressure
Vacuum Breakers
This device is an outgrowth of
the atmospheric vacuum
breaker and evolved in response
to a need to have an atmospher-
ic vacuum breaker that could be
utilized under constant pressure
and that could be tested in line.
A spring on top of the disc and
float assembly, two added gate
valves, test cocks, and an
additional first check, provided
the answer to achieve this
device. See Figure 20.
These units are available in
the general configurations as
shown in Figure 20 in sizes
V2-inch through 10-inch and
have broad usage in the
agriculture and irrigation
market. Typical agricultural and
FIGURE 20.
Pressure vacuum breaker
industrial applications are
shown in Figure 21.
Again, these devices may
be used under constant pressure
but do not protect against
backpressure conditions. As a
result, installation must be at
least 6- to 12-inches higher
than the existing outlet.
A spill resistant pressure
vacuum breaker (SVB) is
available that is a modification
to the standard pressure
vacuum breaker but specifically
designed to minimize water
spillage. Installation and
hydraulic requirements are
similar to the standard pressure
vacuum breaker and the
devices are recommended for
internal use.
Spring
Test cock
First check valve
Test cock
Gate Valve
3/4 inch thru 2 inches
18 • CROSS-CONNECTION CONTROL MANUAL
-------
Double Check with
Intermediate
Atmospheric Vent
The need to provide a compact
device in 14-inch and %-inch
pipe sizes that protects against
moderate hazards, is capable of
being used under constant
pressure and that protects
against backpressure, resulted
in this unique backflow
preventer. Construction is
basically a double check valve
having an atmospheric vent
located between the two checks
(See Figure 22).
Line pressure keeps the
vent closed, but zero supply
pressure or backsiphonage will
open the inner chamber to
atmosphere. With this device,
extra protection is obtained
through the atmospheric vent
capability. Figure 23 shows a
typical use of the device on a
residential boiler supply line.
FIGURE 21.
Typical agricultural and
industrial application of
pressure vacuum breaker.
FIGURE 22.
Double check valve with
atmospheric vent.
1st check
2nd check
FIGURE 23.
Typical residential use of double
check with atmospheric vent.
Automatic feed valve
Air gap
12" minimum above
the highest outlet
FIGURE 24.
Double check valve.
Double Check Valve
A double check valve is
essentially two single check
valves coupled within one body
and furnished with test cocks
and two tightly closing gate
valves (See Figure 24).
The test capability feature
gives this device a big advan-
tage over the use of two
independent check valves in
that it can be readily tested to
determine if either or both
check valves are inoperative
or fouled by debris. Each check
is spring loaded closed and
requires approximately a pound
of pressure to open.
This spring loading
provides the ability to "bite"
through small debris and still
seal—a protection feature not
prevalent in unloaded swing
check valves. Figure 24 shows a
cross section of double check
valve complete with test cocks.
Double checks are commonly
used to protect against low to
medium hazard installations
such as food processing steam
kettles and apartment projects.
They may be used under
continuous pressure and protect
against both backsiphonage and
backpressure conditions.
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At least 6"
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CHAPTER FOUR
19
-------
Double Check Detector
Check
This device is an outgrowth of
the double check valve and is
primarily utilized in fire line
installations. Its purpose is to
protect the potable supply line
from possible contamination or
pollution from fire line chemical
additives, booster pump fire
line backpressure, stagnant
"black water" that sits in fire
lines over extended periods of
time, the addition of "raw"
water through outside fire
pumper connections (Siamese
outlets), and the detection of
any water movement in the fire
line water due to fire line
leakage or deliberate water
theft. It consists of two, spring
loaded check valves, a bypass
assembly with water meter and
double check valve, and two
tightly closing gate valves. See
Figure 25. The addition of test
cocks makes the device testable
FIGURE 25.
Double check detector check.
to insure proper operation of
both the primary checks and
the bypass check valve. In the
event of very low fire line water
usage, (theft of water) the low
pressure drop inherent in the
bypass system permits the low
flow of water to be metered
through the bypass system. In a
high flow demand, associated
with deluge fire capability, the
main check valves open,
permitting high volume, low
restricted flow, through the two
large spring loaded check
valves.
Residential Dual Check
The need to furnish reliable and
inexpensive backsiphonage and
backpressure protection for
individual residences resulted in
the debut of the residential dual
check. Protection of the main
potable supply from household
hazards such as home photo-
graph chemicals, toxic insect
and garden sprays, termite
control pesticides used by
exterminators, etc., reinforced,
a true need for such a device.
Figure 26 shows a cutaway of
the device.
FIGURE 26.
Residential dual check.
It is sized for 1A-, %-, and
1-inch service lines and is
installed immediately down-
stream of the water meter. The
use of plastic check modules
and elimination of test cocks
and gate valves keeps the cost
reasonable while providing
good, dependable protection.
Typical installations are shown
in Figures 27 and 28.
FIGURE 27.
Residential installation.
3.-.0.-.V
i.«:«
:••?.• 3
FIGURE 28.
Copper horn.
Residential
dual check
11/4n meter thread female inlet with
1" NPT thread female union outlet
20 • CROSS-CONNECTION CONTROL MANUAL
-------
Reduced Pressure
Principle Backflow
Preventer
Maximum protection is
achieved against backsiphonage
and backpressure conditions
utilizing reduced pressure
principle backflow preventers.
These devices are essentially
modified double check valves
with an atmospheric vent
capability placed between the
two checks and designed such
that this "zone" between the
two checks is always kept at
least two pounds less than the
supply pressure. With this
design criteria, the reduced
pressure principle backflow
preventer can provide protec-
tion against backsiphonage and
backpressure when both the
first and second checks become
fouled. They can be used under
constant pressure and at high
hazard installations. They are
furnished with test cocks and
gate valves to enable testing
and are available in sizes %-inch
through 10 inch.
Figure 29A shows typical
devices representative of %-inch
through 2-inch size and Figure
29B shows typical devices
representative of 2 Vz -inch
through 10-inch sizes.
FIGURE 29A.
Reduced pressure zone backflow
preventer (3/4-inch thru 2-inches).
c
0
FIGURE 29B.
Reduced pressure zone backflow
preventer (21/2-inches thru 1 fl-
inches).
Reduced pressure zone
1 st check valve 2nd check valve
Relief valve (rotated 90° for clarity)
CHAPTER FOUR • 21
-------
The principles of operation
of a reduced pressure principle
backflow preventer are as
follows:
Flow from the left enters
the central chamber against the
pressure exerted by the loaded
check valve 1. The supply
pressure is reduced thereupon
by a predetermined amount.
The pressure in the central
chamber is maintained lower
than the incoming supply
pressure through the operation
of the relief valve 3, which
discharges to the atmosphere
whenever the central chamber
pressure approaches within a
few pounds of the inlet pres-
sure. Check valve 2 is lightly
loaded to open with a pressure
drop of 1 psi in the direction of
flow and is independent of the
pressure required to open the
relief valve. In the event that
the pressure increases down-
stream from the device, tending
to reverse the direction of flow,
check valve 2 closes, preventing
backflow. Because all valves
may leak as a result of wear or
obstruction, the protection
provided by the check valves is
not considered sufficient. If
some obstruction prevents
check valve 2 from closing
tightly, the leakage back into
the central chamber would
increase the pressure in this
zone, the relief valve would
open, and flow would be
discharged to the atmosphere.
When the supply pressure
drops to the minimum differen-
tial required to operate the
relief valve, the pressure in the
central chamber should be
atmospheric. If the inlet
pressure should become less
than atmospheric pressure,
relief valve 3 should remain
fully open to the atmosphere to
discharge any water which may
be caused to backflow as a
result of backpressure and
leakage of check valve 2.
Malfunctioning of one or
both of the check valves or relief
valve should always be indi-
cated by a discharge of water
from the relief port. Under no
circumstances should plugging
of the relief port be permitted
because the device depends
upon an open port for safe
operation. The pressure loss
through the device may be
expected to average between
10 and 20 psi within the
normal range of operation,
depending upon the size and
flow rate of the device.
Reduced pressure principle
backflow preventers are
commonly installed on high
hazard installations such as
plating plants, where they
would protect against primarily
backsiphonage potential, car
washes where they would
protect against backpressure
conditions, and funeral parlors,
hospital autopsy rooms, etc.
The reduced pressure principle
backflow preventer forms the
backbone of cross-connection
control programs. Since it is
utilized to protect against high
hazard installations, and since
high hazard installations are the
first consideration in protecting
public health and safety, these
devices are installed in large
quantities over a broad range of
plumbing and water works
installations. Figures 31 and 32
show typical installations of
these devices on high hazard
installations.
FIGURE 30.
Reduced pressure zone backflow
preventer — principle of operation.
Reversed direction
of flow
FIGURE 31.
Plating plant installation.
Reduced pressure principle backflow preventer
FIGURE 32.
Car wash installation.
Reduced pressure principle
backflow preventer
22 • CROSS-CONNECTION CONTROL MANUAL
-------
FIGURE 33.
Typical bypass configuration
reduced pressure principle
devices
T
Reduced pressure
principle device
Reduced pressure principle device
Air gap
| [ Drain
Drain
Note: Devices to be set a mm. of 12" and a max. of 30" from the floor and 12" from any wall.
FIGURE 34.
Typical installation reduced
pressure principle device
horizontal illustration.
M
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1 ^
1 I LJ
Reduced pressure
principle device
T,—n n n_. T
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-------
FIGURE 36.
Typical installation double check
valve horizontal and vertical
installation.
FIGURE 37.
Typical installation residential dual
check with straight set and
copperhorn.
Double check valve
Water meter
12" min. 30" max.
Double check valve
(unit to be set at a height
that permits ready access
for testing and service)
Copperhorn with
water meter
*>.'
•P.'
3/4n ball valve
Residential
dual check
Copperhorn with
water meter
Note: Vertical installation only to be used if horizontal
installation cannot be achieved.
3/4n ball valve
3/4n K-copper
24 • CROSS-CONNECTION CONTROL MANUAL
-------
Chapter Five
Testing Procedures
for Backflow
Preventers
Rior to initiating a test of
my backflow device, it is
recommended that the follow-
ing procedures be followed:
1. Permission be obtained from
the owner, or his representative,
to shut down the water supply.
This is necessary to insure that
since all testing is accomplished
under no-flow conditions, the
owner is aware that his water
supply will be temporarily shut
off while the testing is being
performed. Some commercial
and industrial operations
require constant and uninter-
rupted water supplies for
cooling, boiler feed, seal pump
water, etc. and water service
interruption cannot be tolerat-
ed. The water supply to
hospitals and continuous
process industries cannot be
shut off without planned and
coordinated shut downs. The
request to shut down the water
supply is therefore a necessary
prerequisite to protect the
customer as well as limit the
liability of the tester.
Concurrent with the
request for permission to shut
off the water, it is advisable to
point out to the owner, or his
representative, that while the
water is shut off during the test
period, any inadvertent use of
water within the building will
reduce the water pressure to
zero. Backsiphonage could
result if unprotected cross-
connections existed which
would contaminate the building
water supply system. In order
to address this situation, it is
recommended that the owner
caution the inhabitants of the
building not to use the water
until the backflow test is
completed and the water
pressure restored. Additional
options available to the building
owner would be the installation
of two backflow devices in
parallel that would enable a
protected bypass flow around
the device to be tested. Also, if
all water outlets are protected
within the building with
"fixture outlet protection"
backflow devices, cross-
connections would not create a
problem in the event of
potential backsiphonage
conditions occurring while
devices are tested, or for any
other reason.
2. Determine the type of device
to be tested i.e., double check
valve or reduced pressure
principle device.
3. Determine the flow direc-
tion. (Reference directional flow
arrows or wording provided by
the manufacturer on the
device.)
4. Number the test cocks, bleed
them of potential debris, and
assemble appropriate test cock
adapters and bushings that may
be required.
5. Shut off the downstream
(number 2) shut-off valve. (Ref.
Item (1) above.)
6. Wait several moments prior
to hooking up the test kit hoses
when testing a reduced pressure
principle device. If water exits
the relief valve, in all likelihood,
the first check valve is fouled
and it is impractical to proceed
with the testing until the valve
is serviced. This waiting period
is not necessary when testing
double check valves.
7. Hook up the test kit hoses in
the manner appropriate to the
device being tested and the
specific test being performed.
Test personnel are cau-
tioned to be aware and follow
local municipal, county, and
state testing requirements and
guidelines as may be dictated
by local authority. The follow-
ing test procedures are guide-
lines for standard, generally
acceptable test procedures
but may be amended, superced-
ed, or modified by local
jurisdiction.
CHAPTER FIVE • 25
-------
Test Equipment
Er field testing of reduced
x ressure principle backflow
preventers and double check
valve assemblies, a differential
pressure test gauge is utilized
having a 0 to 15 psi range and
a working pressure of 500 psi.
Appropriate length of hoses
with necessary fittings accom-
pany the test gauge. Several
manufactured test kits are
commercially available that
incorporate the differential
gauge, hoses, and fittings and
are packaged for ease of
portability and come with
protective enclosures or straps
for hanging. Calibrated water
columns are commercially
available that are portable and
come with carrying cases.
It is important that all test
equipment be periodically
checked for calibration.
Pressure Vacuum
Breaker
(Figure 38)
Field testing of a pressure
vacuum breaker involves testing
both the internal spring loaded
soft seated check valve as well
as testing the spring loaded air
inlet valve. The testing must be
performed with the device
pressurized and the air inlet
closed. The number 2 shut-off
valve must also be closed and
the air inlet valve canopy
removed.
Method 1
Using a differential pressure
gauge
Test 1 Test the internal check
valve for tightness of 1 psid in
the direction of flow.
1. With the valve body under
pressure, (number 2 shut-
off valve closed and
FIGURE 38.
Air inlet valve canopy
number 1 shut-off valve
open) bleed test cocks
number 1 and number 2.
2. Hook up the high pressure
hose to number 1 test cock
and the low pressure hose
to number 2 test cock.
3. Bleed the high pressure
hose, and low pressure
hose, in that order, and
close the test kit needle
valves slowly.
4. Record the differential
pressure on the gauge. A
reading of 1 psid is
acceptable to insure a tight
check valve.
Test 2 Test the air inlet valve
for a breakaway of 1 psi.
1. Connect the high pressure
hose to test cock number 2,
and bleed the high pressure
hose.
2. Shut off number 1 shut-off
valve.
3. Slowly open the bleed valve
of the test kit, and observe
and record the psi when
the air inlet poppet opens.
This should be a minimum
of 1 psi. Restore the valve
to normal service.
Method 2
Using a water column sight
tube and 90 degree elbow
fitting with bleed needle
Test 1 Test the internal check
valve for tightness of 1 psid in
the direction of flow.
1. Assemble sight tube to test
cock number 1. Open test
cock and fill the tube to a
minimum of 36-inches of
water height.
2. Close number 1 shut-off
valve.
3. Open test cock number 2.
The air inlet valve should
open and discharge water
through number 2 test
cock.
4. Open number 1 test cock.
The sight tube level of
water should drop slowly
until it stabilizes. This
point should be a mini-
mum of 28-inches of water
column which equals 1 psi.
Test 2 Test the air inlet valve
for a breakaway of 1 psi.
1. Assemble sight tube to
test cock number 2. Open
test cock number 2 and fill
the tube to a minimum of
36-inches of water height.
2. Close number 1 shut-off
valve.
3. Bleed water slowly from
the number 2 test cock
bleed needle and observe
the water column height as
it drops.
4. At the point when the air
inlet valve pops open,
record the height of the
water column. This point
should be a minimum of
28-inches of water column
which equals Ipsi.
Restore the valve to normal
service.
Reduced Pressure
Principle Backflow
Preventer
(Figure 39)
Field testing of a reduced
pressure principle backflow
preventer is accomplished
utilizing a differential pressure
gauge. The device is tested for
three optional characteristics:
i.e., (1) the first check valve is
tight and maintains a minimum
of 5 psi differential pressure,
(2) the second check valve is
tight against backpressure and
(3) the relief valve opens at a
minimum of 2 psi below inlet
supply pressure. Testing is
performed as follows:
Step 1 Test to insure that the
first check valve is tight and
maintains a minimum pressure
of 5 psi differential pressure.
1. Verify that number 1 shut-
off valve is open. Close
number 2 shut-off valve.
If there is no drainage
from the relief valve it is
assumed that the first
check is tight.
2. Close all test kit valves.
3. Connect the high pressure
hose to test cock number 2.
4. Connect the low pressure
hose to test cock number 3.
5. Open test cocks number 2
and number 3.
6. Open high side bleed
needle valve on test kit
bleeding the air from the
high hose. Close the high
side bleed needle valve.
7. Open the low side bleed
needle valve on test kit
bleeding air from the low
hose. Close the low side
bleed needle valve. Record
the differential gauge
pressure. It should be a
minimum of 5 psid.
26 • CROSS-CONNECTION CONTROL MANUAL
-------
FIGURE 39.
Control
needle
valves
Step 2 Test to insure that the
second check is tight against
backpressure. (Figure 40)
I. Leaving the hoses hooked
up as in the conclusion of
Step 1 above, connect the
bypass hose to test cock
number 4.
2. Open test cock number 4,
the high control needle
valve and the bypass hose
control needle valve on the
test kit. (This supplies high
FIGURE 40.
Temporary
bypass hose
Bypass hose
pressure water downstream
of check valve number 2.)
If the differential pressure
gauge falls off and water
comes out of the relief
valve, the second check is
recorded as leaking. If the
differential pressure gauge
remains steady, and no
water comes out of the
relief valve, the second
check valve is considered
tight
3. To check the tightness of
number 2 shut-off valve,
leave the hoses hooked up
the same as at the conclu-
sion of Step 2 above, and
then close test cock
number 2. This stops the
supply of any high pressure
water downstream of check
valve number 2. If the
differential pressure gauge
reading holds steady, the
number 2 shut-off valve is
recorded as being tight. If
the differential pressure
gauge drops to zero, the
number 2 shut-off valve is
recorded as leaking.
With a leaking number 2
shut-off valve, the device is, in
most cases, in a flow condition
and the previous readings taken
are invalid. Unless a non-flow
condition can be achieved,
either through the operation of
an additional shut-off down-
stream, or the use of a tempo-
rary compensating bypass hose,
accurate test results will not be
achieved.
Step 3 To check that the relief
valve opens at a minimum
pressure of 2 psi below inlet
pressure.
1. With the hoses hooked up
the same as at the conclu-
sion of Step #2 (3) above,
slowly open up the low
control needle valve on the
test kit and record the
differential pressure gauge
reading at the point when
the water initially starts to
drip from the relief valve
opening. This pressure
reading should not be
below 2 psid.
This completes the
standard field test for a reduced
pressure principle backflow
preventer. Before removal of the
test equipment, the tester
should insure that he opens
number 2 shut-off valve
thereby reestablishing flow.
Also, the test kit should be
thoroughly drained of all water
to prevent freezing by opening
all control needle valves and
bleed needle valves.
All test data should be
recorded on appropriate forms.
(Ref: sample Page 45)
Note: The steps outlined above may
vary in sequence depending upon local
regulations and/or preferences.
CHAPTER FIVE • 27
-------
Double Check Valve
Assemblies
(Figure 41)
Some field test procedures for
testing double check valve
assemblies require that the
number 1 shut-off valve be
closed to accomplish the test.
This procedure may introduce
debris such as rust and tubercu-
lin into the valve that will
impact against check valve
number 1 or number 2 and
compromise the sealing quality.
This potential problem should
be considered prior to the
selection of the appropriate test
method.
Two test methods, one
requiring closing of the number
1 shut-off valve, and one
without this requirement are
presented below:
Method 1
Utilizing the differential
pressure gauge and not
shutting off number 1 shut-off
valve. Figure 41)
Step 1 checking check valve
number 1
1. Verify that the number 1
shut-off is open. Shut off
number 2 shut-off valve.
2. Connect the high hose to
test cock number 2.
3. Connect the low hose to
test cock number 3.
4. Open test cocks 2 and 3.
5. Open high side bleed
needle valve on test kit
bleeding the air from the
high hose. Close the high
side bleed needle valve.
6. Open low side bleed needle
valve on test kit bleeding
the air from the low hose.
Close the low side bleed
needle valve.
FIGURE 41.
Bypass hose
Control
needle
valves
7. Record the differential
gauge pressure reading.
It should be a minimum
of 1 psid.
8. Disconnect the hoses.
Step 2 Checking check valve
number 2.
1. Connect the high hose to
test cock number 3.
2. Connect the low hose to
test cock number 4.
3. Open test cocks number 3
and 4.
4. Open high side bleed
needle valve on test kit
bleeding the air from the
high hose. Close the high
side bleed needle valve.
5. Open low side bleed needle
valve on test kit bleeding
the air from the low hose.
Close the low side bleed
needle valve.
6. Record the differential
gauge pressure reading.
It should be a minimum
of 1 psid.
7. Disconnect the hoses.
To check tightness of
number 2 shut-off valve, both
the check valves must be tight
and holding a minimum of
1 psid. Also, little or no
fluctuation of inlet supply
pressure can be tolerated.
The testing is performed as
follows:
1. Connect the high hose to
number 2 test cock.
2. Connect the low hose to
number 3 test cock.
3. Connect the bypass hose to
number 4 test cock.
4. Open test cocks numbers
2, 3, and 4.
5. Open high side bleed
needle valve on test kit
bleeding the air from the
high hose. Close the high
side bleed needle valve.
6. Open low side bleed needle
valve on test kit bleeding
the air from the low hose.
Close the low side bleed
needle valve.
7. The differential gauge
pressure should read a
minimum of 1 psid.
8. Open the high side control
needle valve and the bypass
hose control needle valve
on the test kit. (This
supplies high pressure
water downstream of check
valve number 2).
9- Close test cock number 2.
(This stops the supply of
any high pressure water
downstream of number 2
check valve), If the
differential pressure gauge
holds steady, the number 2
shut-off valve is recorded as
being tight. If the differen-
tial pressure gauge drops to
zero, the number 2 shut-off
valve is recorded as leaking.
28 • CROSS-CONNECTION CONTROL MANUAL
-------
FIGURE 42.
Duplex gauge
Individual Bourdon gages mounted on a board
Bypass hose
High side hose I \ Low side hose
Bypass hose
High side hose Low side hose
With a leaking number 2
shut-off valve, the device is, in
most cases, in a flow condition,
and the previous test readings
taken are invalid. Unless a non-
flow condition can be achieved,
either through the operation of
an additional shut-off down-
stream, or the use of a tempo-
rary compensating bypass hose,
accurate test results will not be
achieved.
This completes the
standard field test for a double
check valve assembly. Prior to
removal of the test equipment,
the tester should insure that he
opens number 2 shut-off valve
thereby reestablishing flow. All
test data should be recorded on
appropriate forms and the test
kit drained of water.
Method 2
Utilizing "Duplex Gauge" or
individual bourdon gauges,
requires closing number 1
shut-off. (Figure 42)
Step 1 checking check valve
number 1
1. Connect the high hose to
test cock number 2.
2. Connect the low hose to
test cock number 3.
3. Open test cocks number 2
and number 3.
4. Close number 2 shut-off
valve; then close number 1
shut-off valve.
5. By means of the high side
needle valve, lower the
pressure at test cock
number 2 about 2 psi
below the pressure at test
cock number 3. If this
small difference can be
maintained, then check
valve number 1 is reported
as "tight". Proceed to Step
number 2. If the small
difference cannot be
maintained, proceed to
Step number 3.
Step 2 checking check valve
number 2.
Proceed exactly the same
test procedure as in Step
number 1, except that the
high hose is connected to test
cock number 3 and the low
hose connected to test cock
number 4.
Step 3
1. Open shut-off valve
number 1 to repressurize
the assembly.
2. Loosely attach the bypass
hose to test cock number 1,
and bleed from the gauge
through the bypass hose
by opening the low side
needle valve to eliminate
trapped air. Close low side
needle valve. Tighten
bypass hose. Open test
cock number 1.
3. Close number 1 shut-off
valve.
4. By loosening the low side
hose at test cock number 3,
lower the pressure in the
assembly about 10 psi
below normal line
conditions.
5. Simultaneously open both
needle valves. If the check
valve is holding tight the
high pressure gauge will
begin to drop while the
low pressure gauge will
increase. Close needle
valves. If the gauge shows
that a small (no more than
5 psi) backpressure is
created and held, then the
check valve is reported as
tight. If the check valve
leaks, a pressure differential
is not maintained as both
gauges tend to equalize or
move back towards each
other, then the check valve
is reported as leaking.
With both needle valves
open enough to keep the
needles on the gauge
stationary, the amount of
leakage is visible as the
discharge from the
upstream needle valve.
CHAPTER FIVE • 29
-------
Chapter Six
Responsibility
Administration of
a Cross-Connection
Control Program
FIGURE 43.
Air conditioning cooling tower
FIXTURE
OUTLET
PROTECTIVE
DEVICES
Post mix
beverage
machine
Backflow preventer
with intermediate
atmospheric vent
Laboratory faucet double
check valve with
intermediate vacuum breaker
JLJL
Laboratory Sinks
Hose
vacuum
breaker
Slop sink
Reduced pressure
Dedicated A |°ne backflow
line-
Reduced pressure zone
backflow preventer
INTERNAL
PROTECTION
DEVICES
Reduced
pressure zone
backflow
preventer
Reduced
pressure zone
backflow
preventer
Double check valve
backflow
preventer f Cafeteria
cooking
kettle
Reduced pressure,,
zone backflow/
preventer
Containment device
Under the provisions of the
Safe Drinking Water Act of
1974, the Federal Government
has established, through the
EPA (Environmental Protection
Agency), national standards of
safe drinking water. The states
are responsible for the enforce-
ment of these standards as well
as the supervision of public
water supply systems and the
sources of drinking water. The
water purveyor (supplier) is held
responsible for compliance to
the provisions of the Safe
Drinking Water Act, to include
a warranty that water quality
provided by his operation is in
conformance with the EPA
standards at the source, and is
delivered to the customer
without the quality being
compromised as a result of its
delivery through the distribu-
tion system. As specified in the
Code of Federal Regulations
(Volume 40, Paragraph 141.2,
Section (c)) "Maximum contam-
inant level, means the maxi-
mum permissible level of a
contaminant in water which is
delivered to the free flowing
outlet of the ultimate user of a
public water system, except in
the case of turbidity where the
maximum permissible level is
measured at the point of entry
to the distribution system.
Contaminants added to the
water under circumstances
controlled by the user, except
those resulting from corrosion
of piping and plumbing caused
by water quality, are excluded
from this definition."
Figure 43 depicts several
options that are open to a water
purveyor when considering
cross-connection protection to
commercial, industrial, and
residential customers. He may
elect to work initially on the
"containment" theory. This
approach utilizes a minimum of
backflow devices and isolates
the customer from the water
main. It virtually insulates the
customer from potentially
contaminating or polluting the
public water supply system.
While it is recognized that
"containment" does not protect
the customer within his
building, it does effectively
remove him from possible
contamination to the public
water supply system. If the
water purveyor elects to protect
his customers on a domestic
internal protective basis and/or
"fixture outlet protective basis,"
then cross-connection control
protective devices are placed at
internal high hazard locations as
well as at all locations where
cross-connections exist at the
"last free-flowing outlet." This
approach entails extensive
cross-connective survey work on
behalf of the water superinten-
dent as well as constant policing
of the plumbing within each
commercial, industrial and
residential account. In large
water supply systems, fixture
outlet protection cross-
connection control philosophy,
in itself, is a virtual impossibility
to achieve and police due to the
quantity of systems involved,
the complexity of the plumbing
systems inherent in many
industrial sites, and the fact that
many plumbing changes are
made within industrial and
commercial establishments that
do not require the water depart-
ment to license or otherwise
endorse or ratify when contem-
plated or completed.
In addition, internal
plumbing cross-connection
control survey work is generally
foreign to the average water
30
CROSS-CONNECTION CONTROL MANUAL
-------
Method of Action
purveyor and is not normally a
portion of his job description or
duties. While it is admirable for
the water purveyor to accept
and perform survey work, he
should be aware that he runs
the risk of additional liability in
an area that may be in conflict
with plumbing inspectors,
maintenance personnel and
other public health officials.
Even where extensive
"fixture outlet protection,"
cross-connection control
programs are in effect through
the efforts of an aggressive and
thorough water supply cross-
connection control program,
the water authorities should also
have an active "containment"
program in order to address the
many plumbing changes that
are made and that are inherent
within commercial and industri-
al establishments. In essence,
fixture outlet protection
becomes an extension beyond
the "containment" program.
Also, in order for the
supplier of water to provide
maximum protection of the
water distribution system,
consideration should be given to
requiring the owner of a
premise (commercial, industrial,
or residential) to provide at his
own expense, adequate proof
that his internal water system
complies with the local or state
plumbing code(s). In addition,
he may be required to install,
have tested, and maintain, all
backflow protection devices that
would be required—at his own
expense!
The supplier of water
should have the right of entry
to determine degree of hazard
and the existence of cross-
connections in order to protect
the potable water system. By so
doing he can assess the overall
nature of the facility and its
potential impact on the water
system (determine degree of
hazard], personally see actual
cross-connections that could
contaminate the water system,
and take appropriate action to
insure the elimination of the
cross-connection or the installa-
tion of required backflow devices.
To assist the water purvey-
or in the total administration
of a cross-connection control
program requires that all public
health officials, plumbing
inspectors, building managers,
plumbing installers, and
maintenance men participate
and share in the responsibility
to protect the public health and
safety of individuals from cross-
connections and contamination
or pollution of the public water
supply system.
Dedicated Line
Figure 43 also depicts the use
of a "dedicated" potable water
line. This line initiates immedi-
ately downstream of the water
meter and is "dedicated" solely
for human consumption i.e.,
drinking fountains, safety
showers, eye wash stations, etc.
It is very important that this
piping be color coded through-
out in accordance with local
plumbing regulations, flow
direction arrows added, and the
piping religiously policed to
insure that no cross-connections
to other equipment or piping
are made that could compro-
mise water quality. In the event
that it is felt that policing of
this line cannot be reliably
maintained or enforced, the
installation of a containment
device on this line should be a
consideration.
A complete cross-connection
control program requires a
carefully planned and executed
initial action plan followed by
aggressive implementation and
constant follow-up. Proper
staffing and education of
personnel is a requirement to
insure that an effective program
is achieved. A recommended
plan of action for a cross-
connection control program
should include the following
characteristics:
(1) Establish a cross-connection
control ordinance at the local
level and have it approved by
the water commissioners, town
manager, etc., and insure that it
is adopted by the town or
private water authority as a
legally enforceable document.
(2) Conduct public informative
meetings that define the
proposed cross-connection
control program, review the
local cross-connection control
ordinance, and answer all
questions that may arise
concerning the reason for the
program, why and how the
survey will be conducted, and
the potential impact upon the
industrial, commercial and
residential water customers.
Have state authorities and the
local press and radio attend the
meeting.
(3) Place written notices of the
pending cross-connection
control program in the local
newspaper, and have the local
radio station make announce-
ments about the program as a
public service notice.
(4) Send employees who will
administer the program, to a
course, or courses, on backflow
tester certification, backflow
survey courses, backflow device
repair courses, etc.
(5) Equip the water authority
with backflow device test kits.
(6) Conduct meeting(s) with
the local plumbing inspection
people, building inspectors, and
licensed plumbers in the area
who will be active in the
inspection, installations and
repair of backflow devices.
Inform them of the intent of the
program and the part that they
can play in the successful
implementation of the program.
(7) Prior to initiating a survey
of the established commercial
and industrial installations,
prepare a list of these establish-
ments from existing records,
then prioritize the degree of
hazard that they present to the
water system, i.e., plating
plants, hospitals, car wash
facilities, industrial metal
finishing and fabrication,
mortuaries, etc. These will be
the initial facilities inspected for
cross-connections and will be
followed by less hazardous
installations.
(8) Insure that any new
construction plans are reviewed
by the water authority to assess
the degree of hazard and insure
that the proper backflow
preventer is installed concurrent
with the potential degree of
hazard that the facility presents.
(9) Establish a residential
backflow protection program that
will automatically insure that a
residential dual check backflow
device is installed automatically at
every new residence.
(10) As water meters are
repaired or replaced at residen-
ces, insure that a residential
dual check backflow preventer
is set with the new or reworked
water meter. Be sure to have
the owner address thermal
expansion provisions.
CHAPTER SIX • 31
-------
(11) Prepare a listing of all
testable backflow devices in the
community and insure that
they are tested by certified test
personnel at the time intervals
consistent with the local cross-
connection control ordinance.
(12) Prepare and submit
testing documentation of
backflow devices to the State
authority responsible for
monitoring this data.
(13) Survey all commercial and
industrial facilities and require
appropriate backflow protection
based upon the containment
philosophy and/or internal
protection and fixture outlet
protection. Follow up to insure
that the recommended devices
are installed and tested on both
an initial basis and a periodic
basis consistent with the cross-
connection control ordinance.
The surveys should be
conducted by personnel
experienced in commercial and
industrial processes. The owners
or owners representatives,
should be questioned as to what
the water is being used for in
the facility and what hazards
the operations may present to
the water system (both within
the facility and to the water
distribution system) in the
event that a backsiphonage or
backpressure condition were to
exist concurrent with a non-
protected cross-connection. In
the event that experienced
survey personnel are not
available within the water
authority to conduct the survey,
consideration should be given
to having a consulting firm
perform the survey on behalf of
the water department.
Cross-Connection
Control Survey
Work
Coss-connection control
survey work should only
be performed by personnel
knowledgeable about commer-
cial and industrial potential
cross-connections as well as
general industrial uses for both
potable and process water. If
"containment" is the prime
objective of the survey, then
only sufficient time need be
spent in the facility to deter-
mine the degree of hazard
inherent within the facility or
operation. Once this is deter-
mined, a judgment can be
made by the cross-connection
control inspector as to what
type of backflow protective
device will be needed at the
potable supply entrance, or
immediately downstream of the
water meter. In the event that
the cross-connection control
program requires "total"
protection to the last free
flowing outlet, then the survey
must be conducted in depth to
visually inspect for all cross-
connections within the facility
and make recommendations
and requirements for fixture
outlet protective devices,
internal protective devices, and
containment devices.
It is recommended that
consideration be given to the
following objectives when
performing a cross-connection
control survey:
(1) Determine if the survey will
be conducted with a pre-
arranged appointment or
unannounced.
(2) Upon entry, identify
yourself and the purpose of the
visitation and request to see the
plant manager, owner, or
maintenance supervisor in order
to explain the purpose of the
visit and why the cross-
connection survey will be of
benefit to him.
(3) Ask what processes are
involved within the facility and
for what purpose potable water
is used, i.e., do the boilers have
chemical additives? Are air
conditioning cooling towers in
use with chemical additives? Do
they use water savers with
chemical additives? Do they
have a second source of water
(raw water from wells, etc.) in
addition to the potable water
supply? Does the process water
cross-connect with potentially
hazardous chemical etching
tanks, etc.?
(4) Request "as-built" engineer-
ing drawings of the potable
water supply in order to trace
out internal potable lines and
potential areas of cross-
connections.
(5) Initiate the survey by
starting at the potable entrance
supply (the water meter in most
cases) and then proceed with
the internal survey in the event
that total internal protective
devices and fixture outlet
protective devices are desired.
(6) Survey the plant facilities
with the objective of looking for
cross-connections at all potable
water outlets such as:
Hose bibbs
Slop sinks
Wash room facilities
Cafeteria and kitchens
Fire protection and
Siamese outlets
Irrigation outlets
Boiler rooms
Mechanical room
Laundry facilities
(hospitals)
Production floor
(7) Make a sketch of all areas
requiring backflow protection
devices.
(8) Review with the host what
you have found and explain the
findings to him. Inform him
that he will receive a written
report documenting the
findings together with a written
recommendation for corrective
action. Attempt to answer all
questions at this time. Review
the findings with the owner or
manager if time and circum-
stances permit.
(9) Document all findings and
recommendations prior to
preparing the written report.
Include as many sketches or
photos with the final report as
possible. If the located cross
connection(s) cannot be
eliminated, state the generic
type of backflow preventer
required at each cross connec-
tion found.
(10) Consider requiring or
recommending compliance of
the survey findings within a
definitive time frame, (if
appropriate authority is in
effect).
32 • CROSS-CONNECTION CONTROL MANUAL
-------
Chapter Seven
Cross-Connection
Control and Backflow
Prevention Program
'~T~the successful promotion of
_L a cross-connection control
and backflow prevention
program in a municipality
will be dependent upon legal
authority to conduct such a
program. Where a community
has adopted a modern plumb-
ing code, such as the National
Plumbing Code, ASA A40.8-
1955, or subsequent revisions
thereof, provisions of the code
will govern backflow and
cross-connections. It then
remains to provide an ordinance
that will establish a program
of inspection for an elimination
of cross- and backflow connec-
tions within the community.
Frequently authority for such
a program may already be
possessed by the water depart-
ment or water authority. In
such cases no further document
may be needed. A cross-
connection control ordinance
should have at least three
basic parts.
1. Authority for establish-
ment of a program.
2. Technical provisions
relating to eliminating
backflow and cross-
connections.
3. Penalty provisions for
violations.
The following model
program is suggested for
municipalities who desire to
adopt a cross-connection
control ordinance. Communi-
ties adopting ordinances should
check with State health officials
to assure conformance with
State codes. The form of the
ordinance should comply with
local legal requirements and
receive legal adoption from the
community.
CROSS CONNECTION CONTROL
MODEL PROGRAM
WATER DEPARTMENT NAME
ADDRESS
DATE
Approved
Date
Water Department Name
Cross-Connection Control Program
I. Purpose
A. To protect the public potable water supply served by the
( ) Water Department from the possibility of contamination
or pollution by isolating, within its customers internal distribution
system, such contaminants or pollutants which could backflow or
back-siphon into the public water system.
B. To promote the elimination or control of existing cross-
connections, actual or potential, between its customers in-plant
potable water system, and non-potable systems.
C. To provide for the maintenance of a continuing program
of cross-connection control which will effectively prevent the
contamination or pollution of all potable water systems by cross-
connection.
II. Authority
A. The Federal Safe Drinking Water Act of 1974, and the
statutes of the State of ( ) Chapters ( ) the water
purveyor has the primary responsibility for preventing water from
unapproved sources, or any other substances, from entering the
public potable water system.
B. ( ) Water Department, Rules and Regulations,
adopted.
CHAPTER SEVEN
33
-------
III. Responsibility
The Director of Municipal Services shall be responsible for the
protection of the public potable water distribution system from
contamination or pollution due to the backflow or backsiphonage
of contaminants or pollutants through the water service connec-
tion. If, in the judgment of the Director of Municipal Services, an
approved backflow device is required at the city's water service
connection to any customer's promises, the Director, or his
delegated agent, shall give notice in writing to said customer to
install an approved backflow prevention device at each service
connection to his premises. The customer shall, within 90 days
install such approved device, or devices, at his own expense, and
failure or refusal, or inability on the part of the customer to install
said device or devices within ninety (90) days, shall constitute a
ground for discontinuing water service to the premises until such
device or devices have been properly installed.
IV Definitions
A. Approved
Accepted by the Director of Municipal Services as meeting an
applicable specification stated or cited in this regulation, or as
suitable for the proposed use.
B. Auxiliary Water Supply
Any water supply, on or available, to the premises other than
the purveyor's approved public potable water supply.
C. Backflow
The flow of water or other liquids, mixtures or substances,
under positive or reduced pressure in the distribution pipes of a
potable water supply from any source other than its intended
source.
D. Backflow Preventer
A device or means designed to prevent backflow or
backsiphonage. Most commonly categorized as air gap, reduced
pressure principle device, double check valve assembly, pressure
vacuum breaker, atmospheric vacuum breaker, hose bibb vacuum
breaker, residential dual check, double check with intermediate
atmospheric vent, and barometric loop.
D. 1 Air Gap
A physical separation sufficient to prevent backflow between
the free-flowing discharge end of the potable water system and any
other system. Physically defined as a distance equal to twice the
diameter of the supply side pipe diameter but never less than one
(1) inch.
D.2 Atmospheric Vacuum Breaker
A device which prevents backsiphonage by creating an
atmospheric vent when there is either a negative pressure or
subatmospheric pressure in a water system.
D.3 Barometric Loop
A fabricated piping arrangement rising at least thirty five (35)
feet at its topmost point above the highest fixture it supplies. It is
utilized in water supply systems to protect against backsiphonage.
D.4 Double Check Valve Assembly
An assembly of two (2) independently operating spring loaded
check valves with tightly closing shut off valves on each side of the
check valves, plus properly located test cocks for the testing of each
check valve.
D.5 Double Check Valve with Intermediate Atmospheric Vent
A device having two (2) spring loaded check valves separated
by an atmospheric vent chamber.
D.6 Hose Bibb Vacuum Breaker
A device which is permanently attached to a hose bibb and
which acts as an atmospheric vacuum breaker.
D.7 Pressure Vacuum Breaker
A device containing one or two independently operated spring
loaded check valves and an independently operated spring loaded
air inlet valve located on the discharge side of the check or checks.
Device includes tightly closing shut-off valves on each side of the
check valves and properly located test cocks for the testing of the
check valve(s).
D.8 Reduced Pressure Principle Backflow Preventer
An assembly consisting of two (2) independently operating
approved check valves with an automatically operating differential
relief valve located between the two (2) check valves, tightly
closing shut-off valves on each side of the check valves plus
properly located test cocks for the testing of the check valves and
the relief valve.
D.9 Residential Dual Check
An assembly of two (2) spring loaded, independently operat-
ing check valves without tightly closing shut-off valves and test
cocks. Generally employed immediately downstream of the water
meter to act as a containment device.
E. Backpressure
A condition in which the owners system pressure is greater
than the suppliers system pressure.
F. Backsiphonage
The flow of water or other liquids, mixtures or substances into
the distribution pipes of a potable water supply system from any
source other than its intended source caused by the sudden
reduction of pressure in the potable water supply system.
G Commission
The State of (
) Control Commission.
34 • CROSS-CONNECTION CONTROL MANUAL
-------
H. Containment
A method of backflow prevention which requires a backflow
prevention preventer at the water service entrance.
I. Contaminant
A substance that will impair the quality of the water to a
degree that it creates a serious health hazard to the public leading
to poisoning or the spread of disease.
J. Cross-Connection
Any actual or potential connection between the public water
supply and a source of contamination or pollution.
K. Department
City of ( ) Water Department.
L. Fixture Isolation
A method of backflow prevention in which a backflow
preventer is located to correct a cross connection at an in-plant
location rather than at a water service entrance.
M. Owner
Any person who has legal title to, or license to operate or
habitat in, a property upon which a cross-connection inspection is
to be made or upon which a cross-connection is present.
N. Person
Any individual, partnership, company, public or private
corporation, political subdivision or agency of the State Depart-
ment, agency or instrumentality or the United States or any other
legal entity.
O. Permit
A document issued by the Department which allows the use of
a backflow preventer.
P Pollutant
A foreign substance, that if permitted to get into the public
water system, will degrade its quality so as to constitute a moder-
ate hazard, or impair the usefulness or quality of the water to a
degree which does not create an actual hazard to the public health
but which does adversely and unreasonably effect such water for
domestic use.
Q. Water Service Entrance
That point in the owners water system beyond the sanitary
control of the District; generally considered to be the outlet end of
the water meter and always before any unprotected branch.
R. Director of Municipal Services
The Director, or his delegated representative in charge of the
( ) Department of Municipal Services, is invested with the
authority and responsibility for the implementation of a cross-
connection control program and for the enforcement of the
provisions of the Ordinance.
Y Administration
A. The Department will operate a cross-connection control
program, to include the keeping of necessary records, which fulfills
the requirements of the Commission's Cross-Connection Regula-
tions and is approved by the Commission.
B. The Owner shall allow his property to be inspected for possible
cross-connections and shall follow the provisions of the
Department's program and the Commission's Regulations if a
cross-connection is permitted.
C. If the Department requires that the public supply be protected
by containment, the Owner shall be responsible for water quality
beyond the outlet end of the containment device and should utilize
fixture outlet protection for that purpose.
He may utilize public health officials, or personnel from the
Department, or their delegated representatives, to assist him in the
survey of his facilities and to assist him in the selection of proper
fixture outlet devices, and the proper installation of these devices.
VI. Requirements
A. Department
1. On new installations, the Department will provide on-
site evaluation and/or inspection of plans in order to determine
the type of backflow preventer, if any, that will be required, will
issue permit, and perform inspection and testing. In any case, a
minimum of a dual check valve will be required in any new
construction.
2. For premises existing prior to the start of this program,
the Department will perform evaluations and inspections of plans
and/or premises and inform the owner by letter of any corrective
action deemed necessary, the method of achieving the correction,
and the time allowed for the correction to be made. Ordinarily,
ninety (90) days will be allowed, however, this time period may be
shortened depending upon the degree of hazard involved and the
history of the device(s) in question.
3. The Department will not allow any cross-connection to
remain unless it is protected by an approved backflow preventer for
which a permit has been issued and which will be regularly tested
to insure satisfactory operation.
4. The Department shall inform the Owner by letter, of
any failure to comply, by the time of the first re-inspection. The
Department will allow an additional fifteen (15) days for the
correction. In the event the Owner fails to comply with the
necessary correction by the time of the second re-inspection, the
Department will inform the Owner by letter, that the water
service to the Owner's premises will be terminated within a
period not to exceed five (5) days. In the event that the Owner
informs the Department of extenuating circumstances as to why
the correction has not been made, a time extension may be
granted by the Department but in no case will exceed an addi-
tional thirty (30) days.
CHAPTER SEVEN
35
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5. If the Department determines at any time that a serious
threat to the public health exists, the water service will be termi-
nated immediately.
6. The Department shall have on file, a list of Private
Contractors who are certified backflow device testers. All charges
for these tests will be paid by the Owner of the building or
property.
7. The Department will begin initial premise inspections to
determine the nature of existing or potential hazards, following the
approval of this program by the Commission, during the calendar
year ( ). Initial focus will be on high hazard industries and
commercial premises.
B. Owner
1. The Owner shall be responsible for the elimination or
protection of all cross-connections on his premises.
2. The Owner, after having been informed by a letter from
the Department, shall at his expense, install, maintain, and test, or
have tested, any and all backflow preventers on his premises.
3. The Owner shall correct any malfunction of the backflow
preventer which is revealed by periodic testing.
4. The Owner shall inform the Department of any proposed
or modified cross-connections and also any existing cross-
connections of which the Owner is aware but has not been found
by the Department.
5. The Owner shall not install a bypass around any backflow
preventer unless there is a backflow preventer of the same type on
the bypass. Owners who cannot shut down operation for testing of
the device(s) must supply additional devices necessary to allow
testing to take place. (Ref. Fig. 33 page 23.)
6. The Owner shall install backflow preventers in a manner
approved by the Department. (Ref. Figures 3 through 37, pages 23
through 24.)
7. The Owner shall install only backflow preventers ap-
proved by the Department or the Commission.
8. Any Owner having a private well or other private water
source, must have a permit if the well or source is cross-connected
to the Department's system. Permission to cross-connect may be
denied by the Department. The Owner may be required to install
a backflow preventer at the service entrance if a private water
source is maintained, even if it is not cross-connected to the
Department's system.
9- In the event the Owner installs plumbing to provide
potable water for domestic purposes which is on the Department's
side of the backflow preventer, such plumbing must have its own
backflow preventer installed.
10. The Owner shall be responsible for the payment of all fees
for permits, annual or semi-annual device testing, retesting in the
case that the device fails to operate correctly, and second re-
inspections for non-compliance with Department or Commission
requirements.
VII. Degree of Hazard
The Department recognizes the threat to the public water
system arising from cross-connections. All threats will be classified
by degree of hazard and will require the installation of approved
reduced pressure principle backflow prevention devices or double
check valves.
VIII. Permits
The Department shall not permit a cross-connection within
the public water supply system unless it is considered necessary and
that it cannot be eliminated.
A. Cross-connection permits that are required for each
backflow prevention device are obtained from the Department. A
fee of ( ) dollars will be charged for the initial permit and
( ) dollars for the renewal of each permit.
B. Permits shall be renewed every ( ) years and are
non-transferable. Permits are subject to revocation and become
immediately revoked if the Owner should so change the type of
cross-connection or degree of hazard associated with the service.
C. A permit is not required when fixture isolation is achieved
with the utilization of a non-testable backflow preventer.
IX. Existing in-use backflow prevention devices.
Any existing backflow preventer shall be allowed by the
Department to continue in service unless the degree of hazard is
such as to supercede the effectiveness of the present backflow
preventer, or result in an unreasonable risk to the public health.
Where the degree of hazard has increased, as in the case of a
residential installation converting to a business establishment, any
existing backflow preventer must be upgraded to a reduced
pressure principle device, or a reduced pressure principle device
must be installed in the event that no backflow device was present.
X. Periodic Testing
A. Reduced pressure principle backflow devices shall be
tested and inspected at least semi-annually.
B. Periodic testing shall be performed by the Department's
certified tester or his delegated representative. This testing will be
done at the owner's expense.
C. The testing shall be conducted during the Department's
regular business hours. Exceptions to this, when at the request of
the owner, may require additional charges to cover the increased
costs to the Department.
D. Any backflow preventer which fails during a periodic
test will be repaired or replaced. When repairs are necessary,
upon completion of the repair the device will be re-tested at
owners expense to insure correct operation. High hazard situa-
tions will not be allowed to continue unprotected if the backflow
preventer fails the test and cannot be repaired immediately. In
other situations, a compliance date of not more than thirty (30)
days after the test date will be established. The owner is respon-
36
CROSS-CONNECTION CONTROL MANUAL
-------
sible for spare parts, repair tools, or a replacement device. Parallel
installation of two (2) devices is an effective means of the owner
insuring that uninterrupted water service during testing or repair
of devices and is strongly recommended when the owner desires
such continuity. (Ref. Fig. 33 page 23.)
E. Backflow prevention devices will be tested more fre-
quently than specified in A. above, in cases where there is a history
of test failures and the Department feels that due to the degree of
hazard involved, additional testing is warranted. Cost of the
additional tests will be born by the owner.
XI. Records and Reports
A. Records
The Department will initiate and maintain the following:
1. Master files on customer cross-connection tests and/or
inspections.
2. Master files on cross-connection permits.
3. Copies of permits and permit applications.
4. Copies of lists and summaries supplied to the
Commission.
B. Reports
The Department will submit the following to the Commission.
1. Initial listing of low hazard cross-connections to the State.
2. Initial listing of high hazard cross-connections to the
State.
3. Annual update lists of items 1 and 2 above.
4. Annual summary of cross-connection inspections to the
State.
XII. Fees and Charges
The Department will publish a list of fees or charges for the
following services or permits:
1. Testing fees
2. Re-testing fees
3. Fee for re-inspection
4. Charges for after-hours inspections or tests.
Addendum
1. Residential dual check
Effective the date of the acceptance of this Cross-Connection
Control Program for the Town of ( ) all new residential
buildings will be required to install a residential dual check device
immediately downstream of the water meter. (Ref. Figure 37
page 24.) Installation of this residential dual check device on a
retrofit basis on existing service lines will be instituted at a time
and at a potential cost to the homeowner as deemed necessary by
the Department.
The owner must be aware that installation of a residential dual
check valve results in a potential closed plumbing system within
his residence. As such, provisions may have to be made by the
owner to provide for thermal expansion within his closed loop
system, i.e., the installation of thermal expansion devices and/or
pressure relief valves.
2. Strainers
The Department strongly recommends that all new retrofit
installations of reduced pressure principle devices and double check
valve backflow preventers include the installation of strainers
located immediately upstream of the backflow device. The installa-
tion of strainers will preclude the fouling of backflow devices due to
both foreseen and unforeseen circumstances occurring to the water
supply system such as water main repairs, water main breaks, fires,
periodic cleaning and flushing of mains, etc. These occurrences
may "stir up" debris within the water main that will cause fouling
of backflow devices installed without the benefit of strainers.
CHAPTER SEVEN • 37
-------
Appendk A
Appendk B
Partial List of
Plumbing Hazards
Illustrations of
Backsiphonage
Fixtures with Direct
Connections
Description
Air conditioning, air washer
Air conditioning, chilled water
Air conditioning, condenser
water
Air line
Aspirator, laboratory
Aspirator, medical
Aspirator, weedicide and
fertilizer sprayer
Autoclave and sterilizer
Auxiliary system, industrial
Auxiliary system, surface water
Auxiliary system, unapproved
well supply
Boiler system
Chemical feeder, pot-type
Chlorinator
Coffee urn
Cooling system
Dishwasher
Fire standpipe or sprinkler
system
Fountain, ornamental
Hydraulic equipment
Laboratory equipment
Lubrication, pump bearings
Photostat equipment
Plumber's friend, pneumatic
Pump, pneumatic ejector
Pump, prime line
Pump, water operated ejector
Sewer, sanitary
Sewer, storm
Swimming pool
Fixtures with
Submerged Inlets
Description
Baptismal fount
Bathtub
Bedpan washer, flushing rim
Bidet
Brine tank
Cooling tower
Cuspidor
Drinking fountain
Floor drain, flushing rim
Garbage can washer
Ice maker
Laboratory sink, serrated nozzle
Laundry machine
Lavatory
Lawn sprinkler system
Photo laboratory sink
Sewer flushing manhole
Slop sink, flushing rim
Slop sink, threaded supply
Steam table
Urinal, siphon jet blowout
Vegetable peeler
Water closet, flush tank,
ball cock
Water closet, flush valve,
siphon jet
The following illustrates typical
plumbing installations where
backsiphonage is possible.
Backsiphonage
Case I (Fig. 44)
A. Contact Point: A rubber
hose is submerged in a bedpan
wash sink.
B. Causes of Reversed Flow:
(I) A sterilizer connected to the
water supply is allowed to cool
without opening the air vent.
As it cools, the pressure within
the sealed sterilizer drops below
atmospheric producing a
vacuum which draws the
polluted water into the sterilizer
contaminating its contents. (2)
The flushing of several flush
valve toilets on a lower floor
which are connected to an
FIGURE 44.
Backsiphonage (Case 1).
undersized water service line
reduces the pressure at the
water closets to atmospheric
producing a reversal of the flow.
C. Suggested Correction: The
water connection at the bedpan
wash sink and the sterilizer
should be provided with
properly installed backflow
preventers.
Backsiphonage
Case 2 (Fig. 45)
A. Contact Point: A rubber
hose is submerged in a labora-
tory sink.
B. Cause of Reversed Flow:
Two opposite multi-story
buildings are connected to the
same water main, which often
lacks adequate pressure. The
building on the right has
installed a booster pump.
FIGURE 45.
Backsiphonage (Case 2).
n
n
A "U
D D
D D
D D
D D
D D
^P
s~\
D
D
D
D
D
D
D
B
LI
D
D
D
D
D
D
D
^
38
CROSS-CONNECTION CONTROL MANUAL
-------
When the pressure is inad-
equate in the main, the build-
ing booster pump starts
pumping, producing a negative
pressure in the main and
causing a reversal of flow in the
opposite building.
C. Suggested Correction: The
laboratory sink water outlet
should be provided with a
vacuum breaker. The water
service line to the booster pump
should be equipped with a
device to cut off the pump
when pressure approaches a
negative head or vacuum.
Backsiphonage
Case 3 (Fig. 46)
A. Contact Point: A chemical
tank has a submerged inlet.
B. Cause of Reversed Flow:
The plant fire pump draws
suction directly from the city
water supply line which is
insufficient to serve normal
plant requirements and a major
fire at the same time. During a
fire emergency, reversed flow
may occur within the plant.
C. Suggested Correction: The
water service to the chemical
tank should be provided
through an air gap.
FIGURE 46.
Backsiphonage (Case 3).
Backsiphonage
Case 4 (Fig. 47)
A. Contact Point: The water
supply to the dishwasher is not
protected by a vacuum breaker.
Also, the dishwasher has a solid
waste connection to the sewer.
B. Cause of Reversed Flow:
The undersized main serving
the building is subject to
reduced pressures, and therefore
only the first two floors of the
building are supplied directly
with city pressure. The upper
floors are served from a booster
pump drawing suction directly
from the water service line.
During periods of low city
pressure, the booster pump
suction creates negative
pressures in the low system,
thereby reversing the flow.
C. Suggested Correction: The
dishwasher hot and cold water
should be supplied through an
air gap and the waste from the
dishwasher should discharge
through an indirect waste. The
booster pump should be
equipped with a low-pressure
cutoff device.
FIGURE 47.
Backsiphonage (Case 4).
Backsiphonage
Case 5 (Fig. 48)
A. Contact Point: The gasoline
storage tank is maintained full
and under pressure by means of
a direct connection to the city
water distribution system.
FIGURE 48.
Backsiphonage (Case 5).
FIGURE 49.
Backsiphonage (Case 6).
B. Cause of Reversed Flow:
Gasoline may enter the
distribution system by gravity
or by siphonage in the event of
a leak or break in the water
main.
C. Suggested Correction: A
reduced pressure principle
backflow preventer should be
installed in the line to the
gasoline storage tank or a surge
tank and pump should be
provided in that line.
Backsiphonage
Case 6 (Fig. 49)
A. Contact Point: There is a
submerged inlet in the second
floor bathtub.
B. Cause of Reversed Flow:
An automobile breaks a nearby
fire hydrant causing a rush of
water and a negative pressure in
the service line to the house,
sucking dirty water out of the
bathtub.
C. Suggested Correction: The
hot and cold water inlets to the
bathtub should be above the
rim of the tub.
APPENDIX B • 39
-------
Appendk C
Illustrations of
Backpressure
The following presents
illustrations of typical plumbing
installations where backflow
resulting from backpressure is
possible.
Backflow
Case I (Fig. 50)
A. Contact Point: A direct
connection from the city supply
to the boiler exists as a safety
measure and for filling the
system. The boiler water system
is chemically treated for scale
prevention and corrosion
control.
B. Cause of Reversed Flow:
The boiler water recirculation
pump discharge pressure or
backpressure from the boiler
exceeds the city water pressure
and the chemically treated
water is pumped into the
domestic system through an
open or leaky valve.
C. Suggested Correction: As
minimum protection two check
valves in series should be
provided in the makeup
waterline to the boiler system.
An air gap separation or
reduced pressure principle
backflow preventer is better.
FIGURE 50.
Backflow (Case 1).
FIGURE 51.
Backflow (Case 2)
Backflow
Case 2 (Fig. 51)
A. Contact Point: Sewage
seeping from a residential
cesspool pollutes the private
well which is used for lawn
sprinkling. The domestic water
system, which is served from a
city main, is connected to the
well supply by means of a valve.
The purpose of the connection
may be to prime the well
supply for emergency domestic
use.
B. Cause of Reversed Flow:
During periods of low city
water pressure, possibly when
lawn sprinkling is at its peak,
the well pump discharge
pressure exceeds that of the city
main and well water is pumped
into the city supply through an
open or leaky valve.
C. Suggested Correction: The
connection between the well
water and city water should be
broken
Backflow
Case 3 (Fig. 52)
A. Contact Point: A valve
connection exists between the
potable and the non potable
systems aboard the ship.
B. Cause of Reversed Flow:
While the ship is connected to
the city water supply system
for the purpose of taking on
water for the potable system,
the valve between the potable
and nonpotable systems is
opened, permitting contami-
nated water to be pumped into
the municipal supply.
FIGURE 52.
Backflow (Case 3).
C. Suggested Correction:
Each pier water outlet should
be protected against backflow.
The main water service to the
pier should also be protected
against backflow by an air gap
or reduced pressure principle
backflow preventer.
Backflow
Case 4 (Fig. 53)
A. Contact Point: A single-
valved connection exists
between the public, potable
water supply and the fire-
sprinkler system of a mill.
B. Cause of Reversed Flow:
The sprinkler system is nor-
mally supplied from a nearby
lake through a high-pressure
pump. About the lake are large
numbers of overflowing septic
tanks. When the valve is left
open, contaminated lake water
can be pumped to the public
supply.
C. Suggested Correction: The
potable water supply to the fire
system should be through an air
gap or a reduced pressure
principle backflow preventer
should be used.
FIGURE 53.
Backflow (Case 4).
ACME MILLS
40
CROSS-CONNECTION CONTROL MANUAL
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Appendk D
Appendk E
Illustrations of
Air Gaps
The following illustrations describe methods of providing an
air gap discharge to a waste line which may be occasionally or
continuously subject to backpressure.
FIGURE 54.
Air gap to sewer subject to
backpressure—force main.
FIGURE 55.
Air gap to sewer subject to
backpressure—gravity drain.
2xD
Indirect waste
Ball check
Support vanes
Horizontal waste
FIGURE 56.
Fire system makeup tank for a
dual water system.
Illustrations of
Vacuum Breakers
FIGURE 57.
Vacuum breakers.
Brass inset
Rubber sleeve
Flush connection
Cowl nut
Vaccum closes gate
Air enters here
preventing rise of
contaminated liquids
in fixtures
Air vent
FIGURE 58.
Vacuum breaker arrangement for
an outside hose hydrant.
vacuum breaker
1/2nor3/4"EII. m. M.l.galv.
Section "A" "A"
To fire system
(By permission of Mr. Gustave J. Angele
Sr., RE. formerly Plant Sanitary
Engineer, Union Carbide Nuclear
Division, Oak Ridge, Tenn.)
Hand wheel
I.RS. hose adapter
Coupling M.l.galv.
APPENDIX E • 41
-------
Appendk F
Glossary
Air gap The unobstructed
vertical distance through
the free atmosphere
between the lowest
opening from any pipe or
faucet supplying water to a
tank, plumbing fixture, or
other device and the flood-
level rim of the receptacle.
Backflow The flow of water or
other liquids, mixtures, or
substances into the
distributing pipes of a
potable supply of water
from any source or sources
other than its intended
source. Backsiphonage is
one type of backflow.
Backflow Connection Any
arrangement whereby
backflow can occur.
Backflow Preventer A device
or means to prevent
backflow. Backflow
Preventer, Reduced
Pressure Principle Type
An assembly of differential
valves and check valves
including an automatically
opened spillage port to the
atmosphere.
Backsiphonage Backflow
resulting from negative
pressures in the distribut-
ing pipes of a potable water
supply.
Cross-Connection Any actual
or potential connection
between the public water
supply and a source of
contamination or pollution.
Effective Opening The
minimum cross-sectional
area at the point of water
supply discharge, measured
or expressed in terms of
(1) diameter of a circle, or
(2) if the opening is not
circular, the diameter of a
circle or equivalent cross-
sectional area.
Flood-Level Rim The edge of
the receptacle from which
water overflows.
Flushometer Valve A device
which discharges a prede-
termined quantity of water
to fixtures for flushing
purposes and is actuated by
direct water pressure.
Free Water Surface A water
surface that is at atmo-
spheric pressure.
Frostproof Closet A hopper
with no water in the bowl
and with the trap and
water supply control valve
located below frost line.
Indirect Waste Pipe A drain
pipe used to convey liquid
wastes that does not
connect directly with the
drainage system, but which
discharges into the
drainage system through
an air break into a vented
trap or a properly vented
and trapped fixture,
receptacle, or interceptor.
Plumbing The practice,
materials, and fixtures
used in the installation,
maintenance, extension,
and alteration of all piping,
fixtures, appliances and
appurtenances in connec-
tion with any of the
following: sanitary
drainage or storm drainage
facilities, the venting
system and the public or
private water-supply
systems, within or
adjacent to any building,
structure, or conveyance;
also the practice and
materials used in the
installation, maintenance,
extension, or alteration of
storm water, liquid waste,
or sewerage, and water-
supply systems of any
premises to their connec-
tion with any point of
public disposal or other
acceptable terminal.
Potable Water Water free
from impurities present
in amounts sufficient to
cause disease or harmful
physiological effects.
Its bacteriological and
chemical quality shall
conform to the require-
ments of the USEPA
National Primary Drink-
ing Water Regulations and
the regulations of the
public health authority
having jurisdiction.
Vacuum Any absolute pressure
less than that exerted by
the atmosphere.
Vacuum Breaker A device
that permits air into a
water supply distribution
line to prevent
backsiphonage.
Water Oudet A discharge
opening through which
water is supplied to a
fixture, into the atmo-
sphere (except into an open
tank which is part of the
water supply system), to a
boiler or heating system, to
any devices or equipment
requiring water to operate
but which are not part of
the plumbing system.
Water Supply System The
water service pipe, the
water-distributing pipes,
and the necessary connect-
ing pipes, fittings, control
valves, and all appurte-
nances in or adjacent to
the building or premises.
The water supply system
is part of the plumbing
system.
42 • CROSS-CONNECTION CONTROL MANUAL
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Appendk G
Bibliography
Accepted Procedure and Practice in
Cross-Connection Control
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Akron, Ohio 44309-1563.
Angele, Gustave Cross-Connection
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Reaffirmed 1983. Backflow
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APPENDIX G • 43
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Appendk H
Cross-Connection
Survey Form
Date:
Name of Company, Corporation, or Business:
Address:
Name of Contact:
Type of Use: Industrial Commercial Governmental
Location of Service:
Size of Service: Inch Metered?
Require non-interrupted water service?
Does Boiler Feed utilize chemical additives?
Is Backflow protection incorporated?
Are air conditioning cooling towers utilized?
Is Backflow protection incorporated?
Is a Water Saver utilized on condensing lines or cooling towers? N/A D
Is the make-up supply line backflow protected?
Is process water in use, and if so, is it potable supply water or "Raw" water
RawD
Is fire protection water separate from the potable supply?
Are Containment Devices in place?
Summary
Degree of Hazard:
Type of Device recommended for containment: RPZ d
Fixture Outlet protection required?
If so, where?
Other
Yes D No D
Yes D No D
Yes D No D
Yes D No D
Yes D No D
Yes D No D
Yes D No D
Yes D No D
N/A D Potable D
Protected D Unprotected D
Yes D No D
Yes D No D
High D Low D
DCV D None D
Yes D No D
44 • CROSS-CONNECTION CONTROL MANUAL
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Appendk I
Backflow Prevention Device
Test and Maintenance Report
To:
(water purveyor or regulatory agency)
Attn: Cross-connection Control Section
The cross-connection control device detailed hereon has been tested and maintained as required by the
(rules or regulations) of (purveyor or regulatory agency) and is certified to comply with these (rules or
regulations).
Make of device
Model Number
Serial Number
size
located at
Initial Test
Repairs and
Materials Used
Test After Repair
Reduced Pressure Devices
Double Check Devices
1st Check
DC - Closed
Tight D
RP - psid
Leaked 1 — 1
DC-Closed Tight
RP- psid
2nd Check
Closed Tight 1 1
Leaked 1 1
Closed Tight LH
Relief Valve
Opened at
psid
Opened at
psid
Pressure Vacuum Breaker
Air Inlet
Opened at
psid
Did not open 1 1
Opened at
psid
Check Valve
psid
Leaked 1 1
psid
The above is certified to be true.
Firm Name
Firm Address
Certified Tester
Cert. Tester No.
Date
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~o
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