570989007
v>EPA Cross-Connection
Control Manual
United States
Environmental Protection Agency
Office of Water
Office of Drinking Water
First Printing 1973
Reprinted 1974, 1975
Revised 1989
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Preface
Plumbing crossicphnections,
whichare d,elinedras, 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
responsible 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-connections is possible,
but only through thorough
knowledge and vigilance.
Education is essential, for
even those who are
experienced in piping
installations fail to recognize
cross-connection possibilities
and dangers. All
municipalities with public
water supply systems should
have cross-connection control
programs. Those responsible
for institution?! or private
water supp?' should also be
familiar v/if a dangers of
cross-cormt, ns and should
exercise care 1 surveillance
of their syste s.
This Cross- Connection
Control Man al has been
designed as tool for health
officials, we erworks
personnel, paimbers, and any
others involved directly or
indirectly in water supply
distribution systems. It is
intended to be used for
educational, administrative,
and technical reference in
conducting 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.
Previous 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
governmental 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 new 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.
Contents
American Water Works Association Policy on
Cross-Connections iv
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
Index
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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 .... 12
2 Pressure exerted by two feet of water at sea level ... 13
3 Pressure on the free surface of a liquid at sea level . 13
4 Effect of evacuating air from a column 13
5 Pressure relationships in a continuous
fluid system at the same elevation 13
6 Pressure relationships in a continuous
fluid system at different elevations 14
7 Backsiphonage in a plumbing system 14
8 Negative pressure created by constricted flow 14
9 Dynamically reduced pipe pressure(s). 14
10 Valved connection between potable water and
nonpotable fluid 15
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 suppK 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 backtlow preventer 21
29b Reduced pressure zone backflow preventer 21
30 Reduced pressure zone backflow preventer—
principle ol 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
35 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
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An AWWA
Statement of Policy
on Public Water Supply Matters.
Cross Connections (Adopted
by the Board of Directors on
Jan. 26,1970, and revised on
June 24, 1979, and reaffirmed
June 10, 1984)
The American Water Works
Association recognizes that
the water purveyor has a
responsibility to provide its
customers at the service
connection with water that is
safe under all foreseeable
circumstances. Thus, in the
exercise of this
responsibility, the water
purveyor must take
reasonable precaution to
protect the community
distribution system from the
hazards originating on the
premises of its customers that
may degrade the water in the
community distribution
system.
Cross-connection control
and plumbing inspections on
premises of water customers
are regulatory in nature and
should be handled through
the rules, regulations and
recommendations of the
health authority or the
plumbing-code enforcement
agencies having jurisdiction.
The water purveyor,
however, should be aware of
any situation requiring
inspection and/or
reinspection necessary to
detect hazardous conditions
resulting from
cross-connections. If, in the
opinion of the utility,
effective measures consistent
with the degree of hazard
have not been taken by the
regulatory agency, the water
purveyor should take such
measures as he may deem
necessary to ensure that the
community distribution
system is protected from
contamination. Such action
would include the
installation of a backflow
prevention device, consistent
with the degree of hazard at
the service connection or
discontinuance of the service.
In addition, customer use
of water from the community
distribution system for
cooling or other purposes
within the customer's system
and later return of the water
to the community
distribution system is not
acceptable and is opposed by
AWWA.
IV
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Chapter One
Purpose
and Scope
Public health officials have
long been concerned
about cross-connections and
backflow connections in
plumbing systems and in
public drinking water supply
distribution 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
contamination 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 instructing
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
eliminating 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
convenient 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 installations 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.
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Chapter Two
Human Blood in
the Water System
Public Health
Significance of
Cross-Connections
Public health officials have
long 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
contaminants to invade the
public drinking water
through cross-connections are
so general, enteric infections
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 t
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"
(embalming) 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
combination of low water
pressure in conjunction witl
the simultaneous use of the
aspirator. Instead of the bod;
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
Open
Negative supply pressure
Closed
Reverse flow through
aspirator due to
back siphonage
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Burned in the
Shower
Heating System
Anti-Freeze into
Potable Water
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
contaminated with sodium
hydroxide, a strong caustic
solution.
Other residents claimed
that, "It (the water) bubbled
up and looked like Alka
Chemical bulk storage and holding tanks
Seltzer. I stuck my hand
under the faucet and some
blisters came up." 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 hydroxide 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
Water mam
break and
repair
Bangor Maine Water
Department employees
discovered poisonous
anti-freeze 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.
Automobile antifreeze
added to boiler water
Backsiphonage
(reverse flow)
Normal flow
Curb stop with stop and waste dram
Water main
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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
investigation revealed that an
adjacent water customer
complained of salty water
occurring simultaneously
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
ft\7e\\ow gushy stuff"
JL 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
widespread attention and
made the local newspapers.
In addition to being the lead
story on the ABC news
affiliate in Washington, D.C.
and virtually all the
Washington/Baltimore
newspapers that evening. The
news media contended that
lethal pesticides may have
contaminated the water
supply and among the
contaminants was paraquat, a
powerful agricultural
herbicide.
The investigation disclosed
that the water pressure in the
town water mains was
temporarily 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 restoration 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, emergency
arrangements to provide
temporary potable water from
tanker trucks, all contributed
to an expensive and
unnecessary town burden.
Potable town water
I 1
Recommended installation of backflow preventer
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Propane Gas in
the Water Mains
Fire
Hose used
propane tank purging
cross connected to
pnvate_fire hydrant
Recommended
backflow preventer
installation
Water mam
pressure
65psi
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 contaminated.
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 immediate 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
Sroperty and initiating
ushing 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
approximately enough gas to
fill one mile of an 8-inch
water main.
Chlordane and
Heptachlor at the
Housing Authority
'T'he services to seventy five
J. apartments housing
approximately three hundred
people were contaminated
with chlordane and
heptachlor in a city in
Pennsylvania, in December,
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 submerged 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 back-siphonage
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
-------
Boiler Water
Enters High School
Drinking Water
Pesticide in
Drinking Water
Car Wash Water
in the Water Mair
High
school
Recommended installation
Street B of backflow preventer^-^ Leaky check valve's
Toxic rust inhibitor and
defoamant containing
sodium dichromate
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. City chemists
determined that samples
taken contained levels of
chromium as high as 700
parts per million,
"astronomically 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.
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.
A pesticide contaminated a
North Carolina water
system in April, 1986,
prompting 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
complained 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
neighborhood area.
This car wash
cross-connection and
backpressure 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 watei
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
detergent solution. While
emergency crews initiated
flushing operations, further
investigation within the
contaminated area signaled
the problem was probably
Recommended installation
of hose bibb vacuum breaker
backflow preventer
-------
Shipyard
Backflow
Contamination
caused by a car wash, or
laundry, based upon the
soapy nature of the
contaminant. The source was
quickly narrowed down to a
car wash and the proprietor
was extremely cooperative in
admitting 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 delivered 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
i Recommended
,' installation of
backflow preventer
Jo washrooms
Cafeteria drinking fountains
and sanitation water
Reduced pressure principle backflow preventers
should have been installed at dockside outlets
and other locations
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 surrounding areas.
Potable water supply
-------
Chlordane in the
Water Main
Hexavalent
Chromium in
Drinking Water
Tn October, 1979,
Aapproximately 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
elimination. 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
department 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
contaminant, 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.
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
contaminating the potable
water of a large electronic
manufacturing company in
Massachusetts employing
9,000 people. Quantities of
Hexavalent
chromium
added to
chilled water]
50 parts per million
hexavalent chromium were
found in the drinking water
which is sufficient to cause
severe vomiting, diarrhea,
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.
Temporary
chiller
feed pum
_
Recommended installation of
backflow preventer,—x
Recommended installation of hose bibb
vacuum breaker backflow preventer
-------
Employee Health
Problems due to
Cross-Connection
The water used in the chiller
was treated with hexavalent
chromium, a chemical
additive used as an
anti-corrosive agent and an
algicide. As a result, the
chilled water presented a
toxic, non-potable substance
unfit for human consumption
but very 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
installation 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
temporarily installed. This
replacement 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
potable drinking water
supply. Yellowish green
water started pouring out of
the drinking fountains, the
washroom, and all potable
outlets.
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. Investigating
teams suspected that either
the nearby fire could have
siphoned contaminants from
adjacent buildings into the
water mains, or the
contaminants 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 this storage
tank pressure increased
above the supply pressure, as
a result of thermal expansion,
the potential 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 cut-off
switches simultaneously shut
off the storage tank booster
pumps. This combination
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
contaminated water was
delivered throughout the
building.
Roof mounted solar panels
Water mam
Recommended installation
of backflow preventers
backflow
-------
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
Air conditioning units
supplied by a medical center
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 equalled
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.
Glycol/water
pressurized
holding tank
I ^Submerged mlet
I \cross-connection
Recommended
installation
of backflow preventer 'f^.*
It was theorized that
someone in the medical
center flushed a toilet or
turned on a faucet, which in
turn dropped the pressure in
the potable supply line to the
air conditioning 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
unconsious, 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
permitted 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
-Mam water supply
Recommended installation
of backflow preventer
Creosote entered the water
distribution 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 parl
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
pre-determined level. After
the creosote returned to a
higher level, the pump would
re-start. This pump would
lose its prime quite often
prior to the pit refilling, and
-------
Kool-Aid Laced
with Chlordane
Street mam
Pnvate shut-off,-- Recommended installation
of
Recommended installation
of backflow preventers
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, tp the suction
side of the pump. The hose
bibb remained open at all
times in an effort to
continuously keep the pump
primed.
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
professional 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 accomplished. 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. Approximately a
dozen children and three
adults experienced dizziness
and nausea. Fortunately,
none required hospitalization
or medical attention.
Recommended installation
of hose bibb vacuum
breaker backflow preventer
11
-------
Chapter Three
Theory of Backflow
and Backsiphonage
A cross-connection 1 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 Jink between the two
systems. Second, the
resultant force must be
toward the potable supply.
An understanding of the
principles of backflow and
back-siphonage requires an
understanding of the terms
frequently used in their
discussion. Force, unless
completely resisted, will
produce motion. Weight is a
type of force resulting from
the earth's gravitational
attraction. Pressure fPJ 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 absolute = P gage + 14.7 psi
or
P gage = P absolute -14.7 psi
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. Back/low, 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 superimposed cubic
foot of water. The pressure of
the base of the first cube
would also be inreased by
the same amount of 0.866
psig, or two times the
original pressure.
FIGURE i.
Pressure exerted by 1 foot of
water at sea level.
0 433 psig
12
1 See formal definition in the glossary of
the appendix.
-------
If this process were
epeated 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 surface1, 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 are equal to 43.3 psig.
FIGURE 2.
Pressure exerted by 2 feet of
water at sea level.
0 433 psig
1See formal definition in the
glossary of the appendix.
Siphon Theory
Figure 3 depicts the
atmospheric pressure on a
water surface at sea level. An
open tube is inserted
vertically into the water;
atmospheric pressure, which
is 14.7 psia, acts equally on
the surface of the water
within the tube and on the
outside of the tube.
FIGURE 3.
Pressure on the free surface of a
liquid at sea level.
147 psia
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 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 because of the
partial vacuum created by the
drop in pressure. If the faucet
were opened, however, the
Figure 4.
Effect of evacuating air from a
column.
'Zero" Absolute Pressure
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.
FIGURE 5.
Pressure relationships in a
continuous fluid system at the
same elevation.
4 7 psia
The equilibrium condition
is altered by raising one of
the containers so that the
liquid level in one container
is 5 feet above the level of
13
-------
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 level, since
atmosphere cannot support a
column of water greater in
height than 33.9 feet.
FIGURE 6.
Pressure relationships in a
continuous fluid system at
different elevations.
8 2 psia
103 psia
FIGURE 7.
Backsiphonage in a plumbing
system.
Valve open
Valve open
Closed supply
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.
The siphon actions cited
have been produced by
reduced pressures resulting
from a difference in the water
levels at two separated points
within 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
accelerates, 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.
-10 psig
+ 30 psig +30 psig
FIGURE 9.
Dynamically reduced pipe
pressures.
From pollution source
To fixture
Booster pump
One of the common
occurences 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 b\
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 o
the water in the line.
Actually, in the illustration
shown, flow from the source
of pollution would occur
when pressure on the suctioi
side"of the pump is less than
pressure of the pollution
source; but this is back/low,
which will be discussed
below.
The preceding discussion
has described some of the
means by which negative
pressures may be created anc
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 connection
and the submerged inlet.
-------
FIGURE 10.
Valved connection between
potable water and nonpotable
fluid.
Non potable
Potable
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 connection is
usually detectable but
creating a concern on the
FIGURE 11.
Valved connection between
potable water and sanitary
part 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
occasionally 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 industrial
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 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
interconnected 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 differential. 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
complete separation of the
two systems. Other methods
used involve the installation
of mechanical devices. All
methods require routine
inspection and maintenance.
Dual piping systems are
often installed for extra
protection in the event of an
emergency or possible
mechanical failure of one of
the systems. Fire protection
systems are an example.
Another example is the use
of dual water connections to
boilers. These installations
are sometimes
interconnected, thus creating
a health hazard.
The illustrations in part C
of the appendix depict
installations where backflow
under pressure can occur,
describing the
cross-connection and the
cause of the reversed flow.
Sanitary sewer
1 See forma! definition in the glossary of
the appendix.
15
-------
Chapter Four
Air Gap
Methods and
for the Prevention of
Backflow and
Back-Siphonage
A wide choice of devices
exists that can be used to
prevent back-siphonage 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 manufacurers 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 Association
(AWWA), and the University
of California Foundation for
Cross-Connection Control
and Hydraulic Research.
Air gaps are non-mechanical
backflow preventers that are
very effective devices to be
used where either
back-siphonage 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"
"20"
16
An air gap, although an
extremely effective backflow
preventer when used to
prevent back-siphonage and
backpressure conditions,
does interrupt the piping
flow with corresponding 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
encountered 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 expost
the water to the surrounding
air with its inherent bacteria,
dust particles, and other
airborn 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 churnin;
effect as the water enters the
holding tanks. This reduces
the ability of the water to
withstand bacteria
contamination 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 program requiring
periodic inspection 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.
FIGURE 13
Air Gap in a Piping System
Supply piping
tank or reservoir
-------
Barometric Loop
Atmospheric Vacuum
Breaker
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 back-siphonage. 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
These devices are among the
simplest and least expensive
mechanical types of backflow
preventers and, when
installed properly, can
provide excellent protection
against back siponage. 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 back-siphonage.
Figure 15 shows a typical
atmospheric breaker.
In general, these devices
are available in Vz inch
through 3 inch size and must
be installed vertically, must
not have shut-offs
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
back-siphonage protection.
FIGURE 15
Atmospheric Vacuum Breaker
FIGURE 16
Atmospheric Vacuum Breaker
Typical Installation
o
Figure 16 shows the
generally accepted
installation requirements -
note that no shut-off 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.
FIGURE 17
Atmospheric Vacuum Breaker
in Plumbing Supply System
Flow condition
17
-------
Hose Bibb
Vacuum Breakers
Pressure
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
back-siphonage conditions.
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
This device is an outgrowth
of the atmospheric vacuum
breaker and evolved in
response to a need to have an
atmospheric 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
Vz through 10 inch and have
broad usage in the agriculture
and irrigation market.
Typical agricultural and
industrial applications are
shown in Figure 21.
FIGURE 20
Pressure Vacuum Breaker
Test cock
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.
0 ~\ -Spring
Gate valve
2'/2 inches thru 10 inches
18
-------
Double Check with
Intermediate
Atmospheric Vent
The need to provide a
compact device in Yz inch
and 3/4 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 back-siphonage
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 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
IGURE 21
ypical Agricultural and
industrial Application of
ressure Vacuum Breaker
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
gates valves (See Figure 24).
The test capability feature
gives this device a big
advantage 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
back-siphonage and
backpressure conditions.
FIGURE 24
Double Check Valve
19
-------
Double Check Detector
Check
Residential Dual 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
by-pass 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 to
insure proper operation of
both the primary checks and
FIGURE 25
Double Check Detector Check
the by-pass check valve. In
the event of very low fire line
water usage, (theft of water)
the low pressure drop
inherent in the by-pass
system permits the low flow
of water to be metered
through the by-pass 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.
The need to furnish reliable
and inexpensive
back-siphonage 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 photograph chemicals,
toxic insect and garden
sprays, termite control
pesticides used by
exterminators, etc., reinforced
FIGURE 26
Residential Dual Check
a true need for such a devic
Figure 26 shows a cutaway
the device.
It is sized for 1/2, 3/4, anc
1-inch service lines and is
installed immediately
downstream of the water
meter. The use of plastic
check modules and
elimination of test cocks an
gate valves keeps the cost
reasonable while providing
good, dependable protectioi
Typical installations are
shown in Figures 27 and 28
FIGURE 27
Residential Installation
water meter
FIGURE 28
Copper Horn
Residential dual check
1Vi" meter thread female inlet with
1" NPT Thread female union outlet
Water meter
20
-------
Reduced Pressure
Principle Backflow
Preventer
Maximum protection is
achieved against
back-siphonage 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 protection against
back-siphonage 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 2V->
inch through 10 inch sizes.
FIGURE 29A
Reduced Pressure Zone
Backflow Preventer
FIGURE 29B
Reduced Pressure Zone
Backflow Preventer
2a/2 inch thru 10 inches
rfti
Reduced pressure zone
1st check valve 2nd check valve
Relief valve (rotated 90° for clarity)
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 \. 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 pressure.
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
downstream 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
differential 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
indicated 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 back-siphonage
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
considerations 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
direction of flow
Reversed direction of flow
FIGURE 31
Plating Plant Installation
Reduced pressure principle backflow preventer^—-^ ^Z$&
Reduced pressure principle backflow preventer
FIGURE 32
Car Wash Installation
22
-------
FIGURE 33
Typical By-pass Configuration
Reduced Pressure Principle
Devices
FIGURE 34
Typical Installation
Reduced Pressure Principle Device
Horizontal Illustration
Reduced pressure
principle device
Reduced pressure principle device
12' mm 30 max
Note Device to be set 12" minimum from wall
Reduced pressure principle device
V
Air gap
FIGURE 35
Typical Installation
Reduced Pressure Principle Device
Vertical Installation
Dram
Note Devices to be set a mm of 12" and a max of 30" from the floor and
12" from any wall
Reduced pressure principle device
Note (1) Refer to manufacturers installation data for vertical mount
(2) Unit to be set at a height to permit ready access for testing and service
(3) Vertical installation only to be used if horizontal installation cannot be
achieved
23
-------
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
(unit to be set at a height
that permits ready access
for testing and service)
Copperhorn with water meter
3/4" ball valve
Residential dual check
Water meter in copperhorn
3/4" ball valve
3/4" K-copper
Note: Vertical installation only to be used if
horizontal installation cannot be achieved
24
-------
Chapter Five
Testing Procedures
for Backflow
Preventers
Prior to initiating a test of
any backflow device, it is
recommended that the
following 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 uninterrupted water
supplies for cooling, boiler
feed, seal pump water, etc.
and water service
interruption cannot be
tolerated. 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
by-pass 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 back-siphonage
conditios 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
direction. (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
cautioned to be aware and
follow local municipal,
county, and state testing
requirements and guidelines
as may be dictated by local
authority. The following test
procedures are guidelines for
standard, generally
acceptable test procedures
but may be amended,
superceded, or modified by
local jurisdiction.
25
-------
Test Equipment
For field testing of reduced
pressure 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
accompany 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
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.
Air inlet valve canopy
Loaded air inlet valve
Test .cock No 2
No 2 shut off valve
Check valve
Test cock No 1
No 1 shut off valve
FIGURE 38
Bleed the high pressure
hose, and low pressure
hose, in that order, and
close the test kit needle
valves slowly.
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.
3.
4.
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
minimum 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 1
psi.
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 fir;
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
-------
FIGURE 39
Step 2 Test to insure that the
second check is tight against
backpressure. (Figure 40)
1. 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 3'
supplies high pressure
water downstream of
ypass hose
check valve number 2.) If
the differential pressue
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.
To check the tightness of
number 2 shut-off valve,
leave the hoses hooked
up the same as at the
conclusion 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
downstream, or the use
of a compensating
temporary by-pass hose,
(Ref: Fig. 40), 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
conclusion 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)
Temporary b'
FIGURE 40
Note: The steps outlined above
may vary in sequence depending
upon local regulations and/or
preferences.
27
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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 tuberculin 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.
7. Record the differential
gauge pressure reading. It
should be a minimum of
1 psid.
8. Disconnect the hoses.
28
Control needle valves
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.
Bypass hose
FIGURE 41
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 by-pass 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 by-pass 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 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
test readings taken are
invalid. Unless a non-flow
condition can be achieved,
either through the operation
of an additional shut-off
downstream, or the use of a
temporary compensating
by-pass 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.
-------
Duplex gage
Individual Bourdon gages mounted on a board
bypass hose
High side hose/ \Low :
side hose
FIGURE 42
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.
hose
High side hose
Low side hose
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.
Loosely attach the
by-pass hose to test cock
number 1, and bleed
from the gauge through
the by-pass hose by
opening the low side
needle valve to eliminate
trapped air. Close low
side needle valve.
Tighten by-pass hose.
Open test cock number 1.
Close number 1 shut-off
valve.
By loosening the low side
hose at test cock number
3, lower the pressure in
the assembly about 10 psi
below normal line
conditions.
Simultaneously open
both needle valves . If the
check valve is holding
tight the high pressure
gauge will begin to drop
while the low pressue
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
visable as the discharge
from the upstream needle
valve.
29
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Chapter Six
Responsibility
Administration of
A Cross-Connection
Program
FIGURE 43
Air conditioning cooling tower
FIXTURE
OUTLET
PROTECTIVE
DEVICES
ReducJd pressure zone
backfldlv preventer
INTERNAL
PROTECTIVE
DEVICES
acKriow p
with inter
atmosphen
Laboratory faucet double
check valve with
intermediate vacuum breaker
Atmospheric
vacuum breaker
Hose vacuum breaker
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
enforcement 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 distribution
system. As specified in the
Code of Federal Regulations
(Volume 40, Paragraph 141.2,
Section (c)) "Maximum
contaminant level, means the
maximum permissable 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 permissable 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-connectio
protection to commercial,
industrial, and residential
customers. He may elect to
work initially on the
"containment" theory. This
approach utilizes a minimui
of backflow devices and
isolates the customer from
the water main. It virtually
insulates the customer from
potentially contaminating 01
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 tr
public water supply system.
If the water purveyor elects
to protect his customers on
domestic internal protective
basis and/or "fixture outlet
protective basis," then
cross-connection control
protective devices are placec
at internal high hazard
locations as well as at all
locations where
cross-connections exist at th
"last free-flowing outlet."
This approach entails
extensive cross-connective
survey work on behalf of the
water superintendent as wel
as constant policing of the
plumbing within each
commercial, industrial and
residential account. In large
water supply systems, fixtur
outlet protection
cross-connection control
philosophy, in itself, is a
virtual impossibility to
achieve and police due to th
quantity of systems involved
the complexity of the
plumbing systems inherent i
many industrial sites, and th
fact that many plumbing
changes are made within
industrial and commercial
establishments that do not
require the water department
to license or otherwise
endorse or ratify when
contemplated or completed.
30
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Method of Action
In addition, internal
plumbing cross-connection
control survey work is
generally foreign to the
average water 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
agressive 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 industrial
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
installation of required
backflow devices.
To assist the water
purveyor 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.
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
announcements 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
establishments 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
residences, 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.
31
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(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 back-siphonage
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
Cross-connection control
survey work should only
be performed by personnel
knowledgable about
commercial 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
determine the degree of
hazard inherent within the
facility or operation. Once
this is determined, a
judgement 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"
engineering 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 rooms
Laundry facilities (hospitals)
Production floor
(7) Make a sketch of all area
requiring backflow protectio
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 tc
answer all questions at this
time. Review the findings
with the owner or manager i
time and circumstances
permit.
(9) Document all findings
and recommendations prior
to preparing the written
report. Include as many
sketches with the final repo:
as possible and specifically
state the size and generic
type of backflow preventer
required at each
cross-connection found.
32
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Chapter Seven
Cross-Connection
Control
Ordinance Provisions
The successful promotion
of a cross-connection and
backflow-connection control
program in a municipality
will be dependent upon legal
authority to conduct such a
program. Where a community
has adopted a modern
plumbing 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 connections within
the community. Frequently
authority for such a program
may already be possessed by
the water department 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
establishment 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.
Communities 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
33
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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 back-siphonage of
contaminants or pollutants through the water service
connection. If, in the judgement of the Director of
Municipal Services, an approved backflow device is
required at the city's water service connection to any
customer's premises, 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 back-siphonage. 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.I 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 back-siphonage by
creating an atmospheric vent when there is either a
negative pressure or sub-atmospheric 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 back-siphonage.
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 operating 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. Back-siphonage
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
) Water Supply and Pollution
34
The State of (
Control Commission.
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 Department, 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 moderate 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.
V. 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 Regulations 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 permises 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 additional thirty (30) days.
5. If the Department determines at any time that
a serious threat to the public health exists, the water
service will be terminated 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.
35
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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 by-pass 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 approved 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, re-testing 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
owners'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 situations 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
responsible 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.)
36
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E. Backflow prevention devices will be tested more
frequently 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 v
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 3 7
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
installation 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 withing the water
main that will cause fouling of backflow devices
installed without the benefit of strainers.
37
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Appendix A
Appendix 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 1 (Fig. 44)
A. Contact Point: A rubber hose
is submerged in a bedpan wash
sink.
B. Causes of Reversed Flow: (1)
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
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 ho
is submerged in a laboratory
sink.
B. Cause of Reversed Flow: T'
opposite multi-story buildings
connected to the same water
main, which often lacks
adequate pressure. The buildii
on the right has installed a
booster pump. When the
pressure is inadequate in the
main, the building booster pui
starts pumping, producing a
negative pressure in the main
and causing a reversal of flow
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 pun
should be equipped with a
device to cut off the pump wh
pressure approaches a negativ
head or vacuum.
FIGURE 45
Backsiphonage - Case 2.
FIGURE 44
Backsiphonage - case 1.
38
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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 airgap.
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
airgap and the waste from the
dishwasher should discharge
through an indirect waste. The
booster pump should be
equipped with a low-pressure
cutoff device.
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.
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.
FIGURE 48
Backsiphonage - Case 5.
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.
FIGURE 49
Backsiphonage - Case 6.
FIGURE 47
Backsiphonage - case 4.
39
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Appendix C
Illustrations of
Backflow
The following presents
illustrations of typical plumbing
installations where backflow
resulting from backpressure is
possible.
Backflow
Case 1 (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
dishcharge 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 airgap separation or reduced
pressure principle backflow
preventer is better.
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.
FIGURE 51
Backflow - case 2.
Backflow
Case 3 (Fig. 52)
A. Contact Point: A valve
connection exists between the
potable and the nonpotable
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 contaminated water
to be pumped into the municipa
supply.
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 airgap or
reduced pressure principle
backflow preventer.
FIGURE 50
Backflow - case 1.
40
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 normally
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
airgap or a reduced pressure
principle backflow preventer
should be used.
FIGURE 52
Backflow - case 3.
ACME MILLS
Sprinkler system
A
FIGURE 53
Backflow - case 4.
-------
Appendix D
Appendix E
Illustrations of
Airgaps
Illustrations of
Vacuum Breakers
The following illustrations
describe methods of providing
an airgap discharge to a waste
line which may be occasionally
or continuously subject to
backpressure.
FIGURE 54
Airgap to sewer subject to
backpressure - force main.
Ball check
Waste line
Pump
Brass inset
Rubber sleeve
Flush connection
Cowl nut
Vacuum closes gate
Air enters here
preventing rise of
contaminated liquids
in fixtures
Air vent
FIGURE 57
Vacuum breakers
2xD
Indirect waste
FIGURE 55
Airgap to sewer subject to
backpressure - gravity drain.
Ball check
Support vanes
Horizontal waste
Nonpotable supply
FIGURE 56
Fire system makeup tank for a
dual water system.
"A"
-OF
Plan
"A"
'/21' or %" gate valve I
W or %" sch 40 galv
W or %" vacuum bre
'/2"or JA"EII
U
ak
U
rr
LD
r^
R
L P
J-t
M 1
1
4
galv
1 " sleeve, sch 40,
Exterior
building wall
M
I P S hose
/
r ww
Vi" or %"
nipple galv
^T
Coupling (V
el
adapter
I galv
FIGURE 58
Vacuum breaker arrangement
for an outside hose hydrant.
(By permission of Mr Gustave ]. Angele
Sr., P.E. Formerly Plant Sanitary
Engineer, Union "Carbide Nuclear
Division, Oak Ridge, Term )
41
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Appendix F
Glossary
Airgap 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 distributing
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
predetermined quantity of
water to fixtures for flushing
purposes and is actuated by
direct water pressure.
Free Water Surface A water
surface that is at atmospheric
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 airbreak 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 connection
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 connection 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 requirements
of the Public Health Service
Drinking Water Standards or
the regulation 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 Outlet A discharge
opening through which water
is supplied to a fixture, into
the atmosphere (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 connecting
pipes, fittings, control valves,
and all appurtenances in or
adjacent to the building or
premises. The water supply
system is part of the
plumbing system.
42
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\ppendix G
ibliography
ccepted Procedure and Practice
in Cross-Connection Control
ManuaJ, American Water
Works Association, Pacific
Northwest Section, 4th
Edition. Nov.1985.
merican Backflow Prevention
Association, P.O. Box 1563
Akron, Ohio 44309-1563.
ngele, Gustave ].,
Cross-Connection and
Backflow Prevention,
American Water Works
Association. Supplementary
Reading library Series - No.
S106, New York 10016.
Revision of The National
Plumbing Code, ASA
A40.8-1955, Report of the
Public Health Service
Technical Committee on
Plumbing Standards. Sept. 15,
1962, Public Health Service,
Washington 25, D.C.
AWWA Standard For Backflow
Prevention Devices - Reduced
Pressure Principle and
Double Check Valve Types
(C509-78J, American Water
Works Association, Denver,
Colorado, Reaffirmed 1983.
Back/low Prevention and
Cross-Connection Control,
AWWA Manual M14,
American Water Works
Association, Denver, Colorado
1966.
Hack/low Prevention and
Cross-Connection Control,
Ohio EPA, Office of Public
Water Supply. Second
Edition, Revised Mar.15,1977.
Back/low Prevention Devices -
Selection, installation,
Maintenance, and Field
Testing, CSA Standard
B64.10M1981. Canadian
Standards Association,
Dec.1981.
Back/low - The Manual of
Cross-Connection Prevention
in Public Water Supplies,
Missouri Dept. of Natural
Resources.
Canadian Plumbing Code 1980.
NRCC, No.17305, Second
Printing, Issued by the
Associate Committee on the
National Building Code,
Natural Research Council of
Canada, Ottawa.
Control and Elimination of
Cross-Connections, Panel
Discussion, Journal American
Water Works Association,
Vol.50, No.1,1960.
Cross-Connection Complications,
The Capital's Health, Vol.11,
No. 9, Dec.1953, D.C. Dept. of
Public Health, Washington,
D.C.
Cross-Connection Control,
American Water Works
Association, British Columbia
Section, Second Edition,
Jan.1980. Cross-Connection
Control and Back/low
Prevention Device Testing,
New England Water Works
Association, August 1987.
Cross-Connection Control and
Back/low Prevention, Practice
and Procedure Manual,
Administrative Manual, City
of Winnipeg, Manitoba. Third
Edition, April 1980.
Cross-Connection Control,
Backflow Prevention Device
Tester Certification Training
Course, Public Drinking
Water Program, Divison of
Environmental Quality,
Department of Natural
Resources, State of Missouri.
Cross-Connection Control
Manual, Division of Sanitary
Engineering, Tennessee Dept.
of Public Health, 1975.
Cross-Connection Control
Regulation in Washington
State, Washington State Dept.
of Social and Health Services,
Denver, Colorado, 1974.
Second Edition.
Cross-Connection Control, New
York State Dept. of Health,
Jan.1981.
Cross-Connection Control
Program, State of Utah,
Oct.1985, Travis Black.
Cross-Connection Control, Water
Quality Division, Colorado
Department of Health.
Revised March 1983.
Cross-Connection Control
Survey, New England Water
Works Association, August
1987.
CSA Standards on Vacuum
Breakers and Back/low
Preventers, B64 Series 1976
Canadian Standards
Association, Dec.1976.
Dawson, F. M., and Kalinske, A.
A., Report on
Cross-Connections and
Backsiphonage Research,
Technical Bulletin No.l,
National Association of
Plumbing, Heating, Cooling
Contractors, Washington, D.C.
Evaluation of Back/low
Prevention Devices - A State
of the Art, (N B SIR 76-1070)
U.S. Environmental
Protection Agency, Water
Supply Division, Washington,
D.C., June 1976.
Hendrickson, Howard D.
Cross-Connection Control,
Part 1 & 2, August &
September 1981 issues of
Reeves Journal.
How To Prevent Industrial
Cross-Connection Dangers,
Water Works Engineering,
Feb.1962. Manitoba Plumbing
Code 1981, Issued by the
Department of Labour and
Manpower oi the Province of
Manitoba.
Manual of Cross-Connection
Control, Dept. of Health and
Hospitals, Denver, Colorado,
1977.
Manual of Cross-Connection
Control, Foundation for
Cross-Connection Control and
Hydraulic Research,
University of Southern
California, 7th Editions, June
1985.
Manual of Cross-Connection
Control Practices and
Procedures, State of
California, Health and
Welfare Agency, July 1981.
Plumbing and Drainage Act
Regulations, Alberta, As
amended by Alberta
Regulations (295/80).
Regulations Relating To
Cross-Connections, excerpt
from the California
Administrative Code, Title 17,
Public Health, 1956.
Saskatchewan Regulations 8/78,
Regulations Governing
Plumbing and Drainage
Solar Domestic Hot Water
Systems and the Water
Purveyor, American Water
Works Association, Pacific
Northwest Section.
Springer, E. K., and Reynolds, K.
C., De/initions and
Specifications of Double
Check Valve Assemblies and
Reduced Pressure Principle
Back/low Prevention Devices,
University of Southern
California, School of
Engineering Dept. 48-101,
Jan.30,1959.
Taylor, F. B., and Skodje, M. T.,
Cross-Connections, A Hazard
in All Buildings, Modern
Sanitation and Building
Maintenance, Vol.14, No.8,
Aug.1962.
Use of Backflow Preventers for
Cross-Connection Control,
Joint Committee Report,
Journal American Water
Works Association, Vol. 50,
No.12, Dec.1958.
Van Meter, R. O., Backflow
Prevention Hardware, Water
and Wastes Engineering, Pt.l,
Sept.1970; Pt.2, Oct.1970. !
43
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Appendix H
Cross-Connection
Survey Form
Name of Company, Corporation, or Business:
Date:
Address:
Name of Contact:
Type of Use: Industrial
Location of Service:
Size of Service:
Commercial
Governmental
Jnch
Metered?
Require non-interrupted water service?
Does Boiler Feed utilize chemical additives?
Is Backflow protection incorporated?
Are air conditioning cooling towers utilized?
Yes D
Yes D
Yes D
Yes D
Yes D
Is the make-up supply line backflow protected?
Yes D
Other
No D
No D
No D
No D
No D
Is Backflow protection incorporated? Yes D No D
Is a Water Saver utilized on condensing lines or cooling towers? N/A D Yes D No D
No D
Is process water in use, and if so, is it potable supply water or "Raw" water N/A D Potable D
Raw D Protected D Unprotected D
Is fire protection water separate from the potable supply?
Are Containment Devices in place?
Yes D
Yes D
No D
No D
Summary
Degree of Hazard:
Type of Device recommended for containment:
Fixture Outlet protection required?
High D Low D
RPZ D DCV D None D
Yes D
No D
If so, where?.
44
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Appendix 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 (ruJes or regulations] of (purveyor or regulatory agency) and is certified
to comply with these (ruJes or regulations].
Make of device
size
Model Number
Serial Number .
located at
Initial Test
Repairs and
Materials Used
Test
After Repair
Reduced Pressure Devices
Double Check Devices
1st check
DC-Closed Tight EH
RP- psid
Leaked [ |
DC-Closed Tight D
RP- psid
2nd check
Closed Tight D
Leaked 1 1
Closed Tight D
Relief Valve
Opened at
psid
Opened at
psirl
Pressure Vacuum Breaker
Air Inlet
Opened at
psid
Did Not Open
n
Opened at
psid
Check Valve
psid
Leaked I 1
psirl
The above is certified to be true.
Firm Name
Firm Address
Certified Tester.
Cert. Tester No._
_Date
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