Control Manual

Office of Water (4606M)
February 2003                                                                                                        Printed on Recycled Paper

vvEPA     Cross-Connection
              Control Manual
              United States
              Environmental Protection Agency
              Office of Water
              Office of Ground Water and Drinking Water

              First Printing 1973
              Reprinted 1974, 1975
              Revised 1989
              Reprinted 1995
              Technical Corrections 2003

                                Thumbing cross-connections,
                                .[which are defined as actual
                                or potential connections
                                between a potable and non-
                                potable water supply, constitute
                                a serious public health hazard.
                                There are numerous, well-
                                documented cases where cross-
                                connections have been respon-
                                sible for contamination of
                                drinking water, and have
                                resulted in the spread of disease.
                                The problem is a dynamic one,
                                because piping systems are
                                continually being installed,
                                altered, or extended.
                                    Control of cross-connec-
                                tions is possible, but only
                                through thorough knowledge
                                and vigilance. Education is
                                essential,  for even those who are
                                experienced in piping installa-
                                tions fail to recognize cross-
                                connection possibilities and
                                dangers. All municipalities with
                                public water supply systems
                                should have cross-connection
                                control programs. Those
                                responsible for institutional or
                                private water supplies should
                                also be familiar with the
                                dangers of cross-connections
                                and should exercise careful
                                surveillance of their systems.
                                    This  Cross-Connection Control
                                Manual has been designed as a
                                tool for health officials, water-
                                works personnel, plumbers, and
                                any others involved directly or
indirectly in water supply
distribution systems. It is
intended to be used for educa-
tional, administrative, and
technical reference in conduct-
ing cross-connection control
programs. This manual is a
revision of an earlier book
entitled Water Supply and
Plumbing Cross-Connections (PHS
Publication Number 957),
which was produced under the
direction of Floyd B. Taylor by
Marvin T Skodje, who wrote
the text and designed  the
    Many of the original
illustrations and text have been
retained in  this edition. Previ-
ous revisions were done by
Peter  C. Karalekas, Jr. with
guidance from Roger D. Lee
incorporating suggestions made
by the staff of the EPA Water
Supply Division, other govern-
mental agencies, and interested
    This 3rd edition was
produced as a result of an
updated need for cross-
connection control reference
material reflecting an increase
in cross-connection control
activity throughout  the United
States. It has been revised and
re-issued reflecting a demand
for its use, together with
requests for a document that
covers the broad spectrum of
cross-connection control from
both the basic hydraulic
concepts through the inclusion
of a sample program that can
be a guide for a program at the
municipal level. New backflow
devices have been included in
this revision that are now being
produced by manufacturers
reflecting the needs of the
market. Updated actual cross-
connection case histories have
been added containing graphic
schematic illustrations showing
how the incidents occurred and
how cross-connection control
practices could be applied to
eliminate future re-occurrence.
A more detailed explanation of
cross-connection control
"containment" practice has
been included together with the
use for "internal backflow
protective devices" and "fixture
outlet protection".
    This 1989 edition was
prepared by Howard D.
Hendrickson, PE, vice president
of Water Service Consultants,
with assistance from Peter C.
Karalekas, Jr. of Region 1, EPA,
    This latest (2003) edition
has technical corrections
provided by Howard D.
Hendrickson, PE., showing
updates on pages iv, 18, 23, 30,
31, and 32.

American Water Works Association Policy on Cross-Connections

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

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

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
1    Pressure exerted by one foot of water at sea level  ....
2    Pressure exerted by two feet of water at sea level  ....
3    Pressure on the free surface of a liquid at sea level  . . .
4    Effect of evacuating air from a column  	
5    Pressure relationships in a continuous fluid system at
     the same elevation	
6    Pressure relationships in a continuous fluid system at
     different elevations	
7    Backsiphonage in a plumbing system	
8    Negative pressure created by constricted flow  	
9    Dynamically reduced pipe pressure(s)	
... .12

 ... 14
.... 14
11  Valved connection between potable water and sanitary sewer  	15
12  Air gap  	16
13  Air gap in a piping system  	16
14  Barometric loop  	17
15  Atmospheric vacuum breaker 	17
16  Atmospheric vacuum breaker typical installation	17
17  Atmospheric vacuum breaker in plumbing supply system 	17
18  Hose bibb vacuum breaker 	18
19  Typical installation of hose bibb vacuum breaker 	18
20  Pressure  vacuum breaker  	18
21  Typical agricultural and industrial application of
    pressure  vacuum breaker	19
22  Double check valve with atmospheric vent	19
23  Residential use  of double check with atmospheric vent  	19
24  Double check valve	19
25  Double check valve detector check	20
26  Residential dual check	20
27  Residential installation  	20
28  Copper horn 	20
29a Reduced pressure zone  backflow preventer	21
29b Reduced pressure zone  backflow preventer	21
30  Reduced pressure zone  backflow preventer principle of operation  ... 22
31  Plating plant installation  	22
32  Car wash installation	22
33  Typical by-pass configuration, reduced pressure principle devices  ... 23
34  Typical installation, reduced pressure principle device,
    horizontal illustration  	23
3 5  Typical installation, reduced pressure principle device,
    vertical installation 	23
36  Typical installation, double check valve, horizontal and vertical
    installation   	24
37  Typical installation, residential dual check with straight
    set and copper horn	24
38  Pressure  vacuum breaker  	26
39  Reduced pressure principle backflow preventer, Step 1  	27
40  Reduced pressure principle backflow preventer, Step 2  	27
41  Double check valve assemblies, Method 1   	28
42  Double check valve assemblies, Method 2   	29
43  Cross-connection protection, commercial, industrial and  residential   .30
44  Backsiphonage, Case 1   	38
45  Backsiphonage, Case 2   	38
46  Backsiphonage, Case 3   	39
47  Backsiphonage, Case 4  	39
48  Backsiphonage, Case 5   	39
49  Backsiphonage, Case 6  	39
50  Backflow Case  1  	40
51  Backflow Case 2  	40
52  Backflow Case 3  	40
53  Backflow Case 4  	40
54  Air gap to sewer subject to backpressure—force main  	41
55  Air gap to sewer subject to backpressure—gravity drain  	41
56  Fire system makeup tank for a dual water system   	41
57  Vacuum  breakers	41
58  Vacuum  breaker arrangement for an outside hose hydrant	41
10   Valved connection between potable water and nonpotable fluid  .... 15
                                                                                                                   TABLE OF CONTENTS

Statement  of  Policy
on  Public Water Supply  Matters.
                            Cross Connections

                              dopted by the Board of
                                Directors Jan. 26, 1970,
                            revised June 24, 1979, reaf-
                            firmed June 10, 1984 and
                            revised Jan. 28,  1990 and Jan.
                               The American Water
                            Works Association (AWWA)
                            recognizes water purveyors
                            have the responsibility to
                            supply potable water to their
                            customers. In the exercise of
                            this responsibility, water
                            purveyors or other respon-
                            sible authorities must
                            implement, administer, and
                            maintain ongoing backflow
                            prevention and cross-
                            connection control programs
                            to protect public water
                            systems from the hazards
                            originating on the premises
                            of their  customers and from
                            temporary connections that
                            may impair or alter the water
                            in the public water systems.
                            The return of any water to
                            the public water system after
                            the water has been used for
                            any purpose on the
                            customer's premises or
                            within the customer's piping
                            system is unacceptable and
                            opposed by AWWA.
    The water purveyor shall
assure that effective backflow
prevention measures commen-
surate with the degree of
hazard, are implemented to
ensure continual protection of
the water in the public water
distribution system. Customers,
together with other authorities
are responsible for preventing
contamination of the private
plumbing system under  their
control and the associated
protection of the public water
    If appropriate back-flow
prevention measures have not
been taken, the water purveyor
shall take or cause to be  taken
necessary measures to ensure
that the public water distribu-
tion system is protected from
any actual or potential
backflow hazard. Such action
would include the testing,
installation, and continual
assurance of proper operation
and installation of backflow -
prevention assemblies, devices,
and methods commensurate
with the degree of hazard at the
service connection or at the
point of cross connection or
both. If these actions are not
taken, water service shall
ultimately be eliminated.
    To reduce the risk private
plumbing systems pose to the
public water distribution
system, the water purveyor's
backflow prevention program
should include public education
regarding the hazards backflow
presents to the safety of
drinking water and should
include coordination with the
cross connection efforts of local
authorities,  particularly health
and plumbing officials.  In areas
lacking a health or plumbing
enforcement agency, the water
purveyor should additionally
promote the health and safety
of private plumbing systems to
protect its customers from the
hazards of backflow.

Chapter One
and  Scope
    Kblic health officials have
    )ng been concerned
about cross-connections and
backflow connections in
plumbing systems and in public
drinking water supply distribu-
tion systems. Such cross-
connections, which make
possible the contamination of
potable water, are ever-present
dangers. One example of what
can happen is an epidemic that
occurred in Chicago in 1933.
Old, defective, and improperly
designed plumbing and fixtures
permitted the contamination of
drinking water. As a result.
1,409 persons contracted
amebic dysentery; there were
98 deaths. This epidemic, and
others resulting from contami-
nation introduced into a water
supply through improper
plumbing, made clear the
responsibility of public health
officials and water purveyors for
exercising control over public
water distribution systems and
all plumbing systems connected
to them. This responsibility
includes advising  and instruct-
ing plumbing installers in the
recognition and elimination of
    Cross-connections 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
    It might be assumed that
steps for detecting and elimi-
nating cross-connections would
be elementary and obvious.
Actually, cross-connections may
appear in many subtle forms
and in unsuspected places.
Reversal of pressure in the
water may be freakish and
unpredictable. The probability
of contamination of drinking
water through a cross-
connection occurring within a
single plumbing system may
seem remote; but, considering
the multitude of similar
systems, the probability is
                                                             Why do such

                                                             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
                                                                 To combat the dangers of
                                                             cross-connections  and backflow
                                                             connections, education in their
                                                             recognition and prevention is
                                                             needed. First, plumbing
                                                             installers must know that
                                                             hydraulic and pollutional
                                                             factors may combine to produce
                                                             a sanitary  hazard if a cross-
                                                             connection is present. Second,
                                                             they must realize that there are
                                                             available reliable and simple
standard backflow prevention
devices and methods that may
be substituted for the conve-
nient but dangerous direct
connection. And third, it should
be made clear to all that the
hazards resulting from direct
connections greatly outweigh
the convenience gained.  This
manual does not describe all the
cross-connections possible in
piping  systems. It does attempt
to reduce the subject to a
statement of the principles
involved and to make it  clear to
the reader that such installa-
tions are potentially dangerous.
The primary purpose is to
define,  describe, and illustrate
typical  cross-connections and to
suggest simple methods and
devices by which they may be
eliminated without interfering
with the functions of plumbing
or water supply distribution
                                                                                                        CHAPTER ONE  •  1

Chapter Two
                                                        Human Blood  in
                                                        the Water System
Public Health
Significance  of
Cross-Con nections
                                Kblic health officials have
                                ang been aware of the
                            impact that cross-connections
                            play as a threat to the public
                            health. Because plumbing
                            defects are so frequent and
                            the opportunity for contami-
                            nants to invade the public
                            drinking water through cross-
                            connections are so general,
                            enteric illnesses caused by
                            drinking water may occur at
                            most any location and at  any
                                The following documented
                            cases of cross-connection
                            problems illustrate and
                            emphasize how actual cross-
                            connections have compromised
                            the water quality and the public
    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
    Investigation revealed that
the funeral home had been
using a hydraulic aspirator to
drain fluids from the bodies of
human "remains" as part of the
embalming process. The
aspirator directly connected to
the water supply system at a
faucet outlet located on a sink
in the "preparation" (embalm-
ing) room. Water flow through
the aspirator created suction
that was utilized to draw body
fluids through a hose  and
needle attached to the suction
side of the aspirator.
    The contamination of the
funeral home potable water
supply was caused by a combi-
nation of low water pressure in
conjunction with the  simulta-
neous use of the aspirator.
Instead of the body fluids
flowing into  the sanitary drain,
they were drawn in the opposite
direction—into the potable
water supply of the funeral
               Normal operation
        Positive supply pressure Potable water

                                                   Negative supply pressure
                                                      Reverse flow through
                                                      aspirator due to

Burned in  the
A     resident of a small town in
     Alabama, jumped in the
shower at 5 a.m. one morning
in October, 1986, and when he
got out his body was covered
with tiny blisters. "The more I
rubbed it, the worse it got,"  the
60 year old resident said. "It
looked like someone took a
blow torch and singed me."
    He and several other
residents received medical
treatment at the emergency
room of the local hospital after
the water system was  contami-
nated with sodium  hydroxide, a
strong caustic solution.
    Other residents claimed
that, "It (the water) bubbled up
and looked like Alka Seltzer. I
stuck my hand under the faucet
and some blisters came up."
 Chemical bulk storage and holding tanks
One neighbor's head was
covered with blisters after she
washed her hair and others
complained of burned throats
or mouths after drinking the
    The incident began after an
8-inch water main, that fed the
town, broke and was repaired.
While repairing the water
main, one workman suffered
leg burns from a chemical in
the water and required medical
treatment. Measurements of the
ph of the water were as high as
13 in some sections of the pipe.
    Investigation into the cause
of the problem led to a possible
source of the contamination
from a  nearby chemical
company that distributes
chemicals such as sodium
hydroxide. The sodium hydrox-
ide is brought to the plant in
liquid form in bulk tanker
trucks and is transferred to a
holding tank and then pumped
into 55 gallon drums. When
the water main broke, a truck
driver was adding the water
from the bottom of the tank
truck instead of the top, and
sodium hydroxide back-
siphoned into the water main.
                                                   Water main
                                                   break and
Heating System
Anti-Freeze into
Potable Water
    Bangor Maine Water
    Department employees
discovered poisonous antifreeze
in a homeowner's heating
system and water supply in
November, 1981. The incident
occurred when they shut off
'the service line to the home to
make repairs. With the flow of
water to the house cut off,
pressure in the lines in the
house dropped and the anti-
freeze, placed in the heating
system to prevent freeze-up of
an unused hot water heating
system, drained out of the
heating system into house
water lines, and flowed out to
the street. If it had not been
noticed, it would have entered
the homeowner's drinking
water when the water pressure
was restored.
                                                                  added to boiler water
                                                                                                                 Water main
                                                                                                Curb stop with stop
                                                                                                and waste drain
                      Burned in the shower"
                                                                                                         CHAPTER TWO

Salty Drinks
                                Paraquat in the
                                Water System
  In January, 1981, a nationally
   known fast food restaurant
located in southeastern United
States, complained to the water
department that all their soft
drinks were being rejected by
their customers as tasting
"salty" This included soda
fountain beverages, coffee,
orange juice, etc. An investiga-
tion revealed that an adjacent
water customer complained of
salty water occurring simulta-
neously with the restaurant
incident. This second complaint
came from  a water front ship
repair facility that was also
being served by the same water
main lateral. The (investigation
centered on the ship repair
facility and revealed the
     • 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
     • The pumps were primed
by potable city water.
    With the potable  priming
line left  open and the pumps
maintaining pressure in the fire
lines, raw salt water was
pumped through the priming
lines, through the spool sleeve
piece, to the ship repair facility
and the  restaurant.
                             Backflow preventer
                             replaced by spool piece
                               Salt water suction line
                               for fire protection
( <~\7"ellow gushy stuff"
   i  poured from some of
the faucets in a small town in
Maryland, and the State of
Maryland placed a ban on
drinking the water supply.
Residents were warned not to
use the water for cooking,
bathing, drinking or any other
purpose except for flushing
    The incident drew wide-
spread attention and made the
local newspapers. In addition to
being the lead story on the
ABC news affiliate in Washing-
ton, D.C. and virtually all the
Washington/Baltimore news-
papers that evening. The news
media contended that lethal
pesticides may have contami-
nated the water supply and
among the contaminants was
paraquat, a powerful agricul-
tural herbicide.
    The investigation disclosed
that  the water pressure in the
town water mains was tempo-
rarily reduced due to a water
pump failure in the town water
supply pumping system.
Coincidentally, a gate valve
between a herbicide chemical
holding tank and the town
water supply piping had been
left open. A lethal cross-
connection had been created
that permitted the herbicide to
flow into the potable water
supply system. Upon restora-
tion of water pressure, the
herbicides flowed into the many
faucets and outlets on the town
water distribution system.
    This cross-connection
created a needless and costly
event that fortunately did not
result in serious illness or loss of
life. Door-to-door public
notification, extensive  flushing,
water sample analysis, emer-
gency arrangements to provide
temporary potable water from
tanker trucks, all contributed to
an expensive and unnecessary
town burden.
                                                                                          Recommended installation of
                                                                                             backflow preventer

  Propane Gas in the
  Water Mains
Hose used for
 propane tank
 purging cross
  to private
 fire hydrant
  Water main
    65 psi
      Hundreds of people were
       evacuated from their
 homes and businesses on an
 August afternoon in a town in
 Connecticut in 1982  as a result
 of propane entering the city
 water supply system. Fires were
 reported in two homes  and the
 town water supply was con-
 taminated. One five-room
 residence was gutted by a blaze
 resulting from propane gas
 "bubbling and hissing"  from a
 bathroom toilet and in  another
 home a washing machine
 explosion blew a woman
 against a wall. Residents
 throughout the area reported
 hissing, bubbling  noises,
 coming from washing
 machines, sinks and toilets.
 Faucets sputtered out small
 streams of water mixed with
 gas and residents in the area
 were asked to evacuate their
      This near-disaster occurred
 in one, 30,000 gallon capacity
 liquid propane tank when the
 gas company initiated immedi-
ate repair procedures. To
start the repair, the tank was
"purged" of residual propane
by using water from one of two
private fire hydrants located on
the property. Water purging
is the preferred method of
purging over the use of carbon
dioxide since it is more positive
and will float out any sludge as
well as any gas vapors. The
"purging" consisted of hooking
up a hose to one of the private
fire hydrants located on the
property and initiating flushing
    Since the vapor pressure of
the propane residual in the tank
was 85 to 90 psi., and the water
pressure was only 65 to 70 psi.,
propane gas backpressure
backflowed into the water
main. It was estimated that the
gas flowed into the water mains
for about 20 minutes and that
about 2,000 cubic feet of gas
was involved. This was approxi-
mately enough gas to fill one
mile of an 8-inch water main.
Chlordane and
Heptachlor at the
Housing Authority

'~T~the services to seventy five
 _L apartments housing
approximately three hundred
people were contaminated with
chlordane and heptachlor in a
city in Pennsylvania, in Decem-
ber, 1980. The insecticides
entered the water supply
system while an exterminating
company was applying them as
a preventative measure against
termites.  While the pesticide
contractor was mixing the
chemicals in a tank truck with
water from a garden hose
coming from one of the
apartments, a workman was
cutting into a 6-inch main line
to install  a gate valve. The end
of the garden hose was sub-
merged in the tank containing
the pesticides, and at the same
time, the water to the area was
shut off and the lines being
drained prior to the installation
of the gate valve. When the
workman cut the 6-inch line,
water started to drain out of the
cut, thereby setting up a
backsiphonage condition. As a
result, the chemicals were
siphoned out of the truck,
through the garden hose, and
into the system, contaminating
the seventy five apartments.
    Repeated efforts to clean
and flush the lines were not
satisfactory  and it was finally
decided to replace the water
line and all  the plumbing that
was affected. There were no
reports of illness, but residents
of the housing authority were
told not to use any tap water
for any purpose and they were
given water that was trucked
into the area by volunteer fire
department personnel. They
were without their normal
water supply for 27 days.
                           Recommended installation
                           of hose bibb vacuum breaker
                        *!{ backflow preventer
                                                                                                            CHAPTER TWO

Boiler Water
Enters High School
Drinking Water
                High School
           Recommended installation
             of backflow preventer ^    Leaky check valves
           Toxic rust inhibitor and
            defoamant containing
             sodium dichromate
A     high school in New
     Mexico, was closed for
several days in June 1984 when
a home economics teacher
noticed the water in the potable
system was yellow.  Qty
chemists  determined that
samples taken contained levels
of chromium as high as 700
parts per  million, "astronomi-
cally higher than the accepted
levels of .05 parts per million."
The head chemist said that it
was miraculous that no one was
seriously injured or killed by the
high levels of chromium. The
chemical  was identified as
sodium dichromate, a toxic
form of chromium used in
heating system boilers to inhibit
corrosion of the metal parts.
                                 High school boilers
                                  No students or faculty
                              were known to have consumed
                              any of the water; however, area
                              physicians and hospitals advised
                              that if anyone had consumed
                              those high levels of chromium,
                              the symptoms would be nausea,
                              diarrhea, and burning of the
                              mouth and throat. Fortunately,
                              the home economics teacher,
                              who first saw the discolored
                              water before school started,
                              immediately covered all water
                              fountains with towels so that
                              no one would drink the water.
                                  Investigation disclosed
                              that chromium used in the
                              heating system boilers to inhibit
                              corrosion of metal parts entered
                              the potable water supply
                              system as a result of backflow
                              through leaking check valves
                              on the boiler feed lines.
                                                              Pesticide in
                                                              Drinking Water
A     pesticide contaminated a
     North Carolina water
system in April, 1986, prompt-
ing the town to warn residents
of 23 households not to drink
the water. The residents in the
affected area were supplied
drinking water from a tank
truck parked in the parking lot
of a downtown office building
until the condition could be
cleared up. Residents com-
plained of foul smelling water
but there were no reports of
illness from ingesting the water
that had been contaminated
with a pesticide containing
chlordane and heptachlor.
    Authorities stated that the
problem occurred when a water
main broke at the same time
that a pest control service was
filling a pesticide truck with
water. The reduction in pressure
caused the pesticide from inside
the tank to be sucked into the
building's water main. The
pesticide contaminated the
potable water supply of the
office building and neighbor-
hood area.
Car Wash Water
in the Water Main

    Tiis car wash cross-
    connection and back-
pressure incident, which
occurred in February,  1979,
in the state of Washington,
resulted in backflow chemical
contamination of approximately
100 square blocks of water
mains. Prompt response by the
water department prevented a
potentially hazardous water
quality degradation problem
without a recorded case of
    Numerous complaints of
grey-green and "slippery" water
were received by the water
department coming from the
same general area of town. A
sample brought to the water
department by a customer
confirmed the reported problem
and preliminary analysis
indicated contamination with
what appeared to be a deter-
gent solution. While emergency
crews initiated flushing opera-
tions, further investigation
within the contaminated area
signaled the problem was
probably caused by a car wash,
                                                                       Recommended installation
                                                                       of hose bibb vacuum breaker
                                                                       backflow preventer

or laundry, based upon the
soapy nature of the contami-
nant. The source was quickly
narrowed down to a car wash
and the proprietor was ex-
tremely cooperative in admit-
ting  to the problem and
explaining how it had occurred.
The  circumstances leading up
to the incident were as follows:
     • On Saturday, February
10, 1979, a high pressure pump
broke down at the car wash.
This pump recycled reclaimed
wash and rinse water and
pumped it to the initial
scrubbers of the car wash. No
potable plumbing connection
is normally made to the car
wash's scrubber system.
     • After the pump broke
down, the car wash owner
was able to continue operation
by connecting a 2-inch hose
section temporarily between the
potable supply within the car
wash, and the scrubber cycle
     • On Monday, February
12, 1979, the owner repaired
the high pressure pump and
resumed normal car wash
operations. The 2-inch hose
connection (cross-connection)
was not removed!
     • Because of the cross-
connection, the newly repaired
high pressure pump promptly
pumped a large quantity of
the reclaimed wash/rinse water
out of the car wash and into a
12-inch water main in the
street. This in turn was deliv-
ered to the many residences
and commercial establishments
connected to the water main.
    Within 24 hours of the
incident, the owner of the car
wash had installed  a 2-inch
reduced pressure principle
backflow preventer on his
water service and all car wash
establishments in Seattle that
used a wash water  reclaim
system were notified of the
state requirement for backflow
            Wax injectors
	Soap injectors
 raw water
                                       Cafeteria drinking fountains
                                       and sanitation water
                        * Reduced pressure principle backflow
                          preventers should have been installed
                          at dockside outlets and other locations
                                      Reclaim tanks
              backflow preventer
            To restrooms
       Water fountains at an East
       Coast Shipyard were
posted "No Drinking" as
workers flushed the water lines
to eliminate raw river water
that had entered the shipyard
following contamination from
incorrectly connected water
lines between ships at  the pier
and the shipyard. Some third
shift employees drank the
water before the pollution
was discovered and later
complained of stomach cramps
and diarrhea.
    The cause of the problem
was a direct cross-connection
between the on-board salt
water fire protection water
system and the fresh water
connected to one of the ships at
the dock. While the shipyard
had been aware of the need
for backflow protection at the
dockside tie up area, the device
had not been delivered and
installed prior to  the time of the
incident. As a result, the salt
water on-board fire  protection
system, being at a greater
pressure than the potable
supply, forced the salt water,
through backpressure, into the
shipyard potable supply.
    Fortunately, a small
demand for potable water at
the time of the incident
prevented widespread pollution
in the shipyard and  the sur-
rounding areas.
                                                                 water supply
                                                                                                            CHAPTER TWO

Chlordane in the
Water Main
Tn October, 1979, approxi-
JLmately three gallons of
chlordane, a highly toxic
insecticide, was sucked back
(back-siphoned) into the water
system of a residential area of
a good sized eastern city.
Residents complained that the
water "looked milky,  felt greasy,
foamed and smelled," and as
one woman put it, "It was
similar to a combination of
kerosene and Black Flag
    The problem developed
while water department
personnel were repairing a
water main. A professional
exterminator,  meanwhile, was
treating a nearby home with
chlordane for termite elimina-
tion. The workman for the
exterminator company left one
end of a garden hose that was
connected to an outside hose
bibb tap in a barrel of diluted
pesticide. During the water
service interruption, the
chlordane solution was back-
siphoned from the barrel
through the house and into the
water mains.
    Following numerous
complaints, the water depart-
ment undertook an extensive
program of flushing of the
water mains and hand delivered
letters telling residents to flush
their lines for four hours before
using the water. Until the water
lines were clear of the contami-
nant, water was hand-hauled
into homes, and people went
out of their homes for showers,
meals and every other activity
involving potable water.
Fortunately, due to the obvious
bad taste, odor and color of the
contaminated water, no one
consumed a sufficient quantity
to endanger health.
Chromium in
Drinking Water
  In July, 1982, a well meaning
   maintenance mechanic, in
attempting to correct a fogging
lens in an overcooled laser
machine, installed a tempering
valve in the laser cooling line,
and inadvertently set the stage
for a backpressure backflow
incident that resulted in
hexavalent chromium contami-
nating the potable water of a
large electronic manufacturing
company in  Massachusetts
employing 9,000 people.
Quantities of 50 parts per
million hexavalent chromium
were found in the drinking
water which is sufficient to
cause severe vomiting, diarrhea,
 added to
 chilled water
and intestinal sickness.
Maintenance crews working
during the plant shutdown
were able to eliminate the cross-
connection and thoroughly
flush the potable water system,
thereby preventing a serious
health hazard from occurring.
    The incident occurred as
    • Laser machine lenses
were kept cool by circulating
chilled water that came from a
large refrigeration chiller. The
water used in the chiller was
treated with hexavalent
chromium, a chemical additive
used as an anticorrosive agent
and an algicide. As a result, the
chilled water presented a toxic,
non-potable substance unfit for
human consumption but very
                                                         feed pump J
                                                           Hot water
                                                                  Recommended installation of
                                                                  backflow preventer  —.
                                                                                            /'To plant vending machines
     Recommended installation of hose bibb
     vacuum breaker backflow preventer

acceptable for industrial process
water. No health hazard was
present as long as the piping
was identified, kept separate
from potable drinking water
lines, and not cross-connected
to the potable water supply.
    • A maintenance
mechanic correctly reasoned
that by adding a tempering
valve to the chilled water line,
he could heat up the water a bit
and eliminate fogging of the
laser lenses resulting from the
chilled water being too cold.
The problem with the installa-
tion of the tempering valve was
that a direct cross-connection
had been inadvertently made
between the toxic chilled water
and the potable drinking water
    • Periodic maintenance
to the chiller system was
performed in the summer,
requiring that an alternate
chiller feed pump be tempo-
rarily installed. This replace-
ment pump had an outlet
pressure of 150  psi, and
promptly established an
imbalance of pressure at the
tempering valve, thereby over-
pressurizing the 60 psi, potable
supply. Backpressure backflow
resulted and pushed the toxic
chilled water from the water
heater and then into the plant's
potable drinking water supply.
"Yellowish green water started
pouring out of the drinking
fountains, the washroom, and
all potable outlets.
Employee  Health
Problems due to

A     cross-connection incident
     occurring in a modern
seven-story office building
located in a large city in New
Hampshire, in March, 1980,
resulted in numerous cases of
nausea, diarrhea, loss of time
and employee complaints as to
the poor quality of the water.
    On Saturday, March 1,
1980, a large fire occurred two
blocks away from a seven-story
office building in this large
New Hampshire city. On
Sunday, March 2, 1980, the
maintenance crew of the office
building arrived to perform the
weekly cleaning, and after
drinking the water from the
drinking fountains, and
sampling the coffee from the
coffee machines, noticed that
the water smelled rubbery and
had a strong bitter taste. Upon
notifying the Manchester Water
Company, water samples were
taken and preliminary analysis
disclosed that the contaminants
found were not the typical
contaminants associated with
fire line disturbances. Investi-
gating teams suspected that
either the nearby fire could
have siphoned contaminants
from adjacent buildings into the
water mains, or the contamina-
tion could have been caused by
a plumbing deficiency occurring
within the seven story building
    Water ph levels of the
building water indicated that
an injection of chemicals had
probably taken place within the
seven-story building. Tracing of
the water lines within the
building pinpointed a 10,000
gallon hot-water storage tank
that was used for heat storage
in the solar heating system. It
did not have any backflow
protection on the make-up
supply line! As the storage tank
pressure increased above the
supply pressure, as a result of
thermal expansion, the poten-
tial for backpressure backflow
was present. Normally, this
would not occur because a
boost pump in the supply line
would keep the supply pressure
to the storage tank always
greater than the highest  tank
pressure. The addition of rust
inhibiting chemicals to this
tank greatly increased the
degree of hazard of the liquid.
Unfortunately, at the same time
that the fire took place, the
pressure in the water mains was
reduced to a dangerously low
pressure and the low  pressure
cutoff switches simultaneously
shut off the storage tank
booster pumps. This  combina-
tion allowed the boiler water,
together with its chemical
contaminants, the opportunity
to enter the potable water
supply within the building.
When normal pressure was
reestablished in the water
mains, the booster pumps
kicked in, and the contami-
nated water was delivered
throughout the building.
Roof mounted solar panels
                                                                               Water  i
                                                                                             Recommended installation
                                                                                             of backflow preventers
                                                                                                            CHAPTER TWO

Dialysis  Machine
                                                                 Creosote  in the
                                                                 Water Mains
   Ethylene glycol, an anti-
    freeze additive to air
conditioning cooling tower
water, inadvertently entered the
potable water supply system in
a medical center in Illinois in
September, 1982, and two of
six dialysis patients succumbed
as a direct or indirect result  of
the contamination.
    The  glycol was added to
the air conditioning water, and
the glycol/water mix was  stored
in a holding tank  that was an
integral part of the medical
center's air conditioning cooling
system. Pressurized make-up
water to  the holding tank was
supplied  by a medical center
               Air conditioning units
potable supply line and fed
through a manually operated
control valve. With this valve
open, or partially open, potable
make-up water flowed slowly
into the glycol/water mixture in
the holding tank until it filled
to the point where the pressure
in the closed tank equaled the
pressure in the potable water
supply feed line. As long as the
potable feed line pressure was at
least equal to, or greater than,
the holding tank pressure, no
backflow could occur. The stage
was set for disaster, however.
    It was theorized  that
someone in the medical center
flushed a toilet or turned on a
                                    holding tank
                                             Submerged inlet
                     Recommneded installation
                        of backflow preventer
faucet, which in turn dropped
the pressure in the potable
supply line to the air condition-
ing holding tank. Since the
manually operated fill valve was
partially open, this allowed the
glycol/water mixture to enter
the medical center potable
pipelines and flow into the
dialysis equipment. The dialysis
filtration system takes out trace
chemicals such as those used in
the city water treatment plant,
but the system could not
handle the  heavy load of
chemicals that it was suddenly
subjected to.
    The effect upon the dialysis
patients was dramatic: patients
became drowsy, confused and
fell unconscious, and were
promptly removed to intensive
care where  blood samples were
taken. The blood samples
revealed a build-up of acid and
the medical director stated that,
"Something has happened in
dialysis." Dialysis  was repeated
on the patients a second and
third  time.
    Tests of the water supply to
the filtration system quickly
determined the presence of "an
undesirable chemical in the
water purification system." The
partially open fill valve was
then found that it had permit-
ted the glycol water mix to
drain from  the air conditioning
holding tank into the medical
center's potable supply lines
and then into the dialysis
filtration system equipment.
                                                       Backpressure backflow
                                                                    Main water
      Cosote entered the water
      [istribution system of a
southeastern county water
authority in Georgia, in
November, 1984, as a result of
cross-connection between a
%-inch hose that was being
used as a priming line between
a fire service connection and the
suction side of a creosote pump.
The hose continually supplied
water to the pump to ensure
the pump was primed at all
times. However, while repairs
were being made to a private
fire hydrant, the creosote back-
siphoned into the water mains
and contaminated a section of
the water distribution system.
    Detailed investigation of
the cause of the incident
disclosed that the wood
preservative company, as part of
their operation, pumped
creosote from collective pits to
other parts of their operation.
The creosote pump would
automatically shut off when the
creosote in the pit was lowered
to a predetermined level. After
the creosote returned to a
higher level, the pump would
restart. This pump would lose
its prime quite often prior to
the pit refilling, and to prevent
the loss of prime, the wood
preservative company would
connect a hose from a %-inch
hose bibb, located on the fire
service line, to the suction side
of the pump. The hose bibb
remained  open at all times in an
effort to continuously keep the
pump primed.
                                                     Recommended installation
                                                      of backflow preventer

                                                                 Kool-Aid  Laced
                                                                 With  Chlordane
   Street main              Private shut-off (7^ Recommended installation
                                   / /}    of backflow preventers
            Creosote pump   Process        ~
                      Recommended installation /..
                        of backflow preventers
contaminated flow
     Repairs were necessary to
one of the private fire hydrants
on the wood preservative
company property, necessitating
the shutting down of one of two
service lines and removal of the
damaged fire hydrant for repair.
Since the hydrant was at a
significantly lower level than
the creosote pit, the creosote
back-siphoned through a %-
inch pump priming hose
connecting the creosote pit to
the fire service line.
    After the repairs were
made to the hydrant, and the
water service restored, the
creosote, now in the fire lines,
was forced into the main water
distribution  system.
  In August, 1978, a profes-
   sional exterminator was
treating a church located in a
small town in South Carolina,
for termite and pest control.
The highly toxic insecticide
chlordane was being mixed
with water in small buckets,
and garden hoses were left
submerged in the buckets while
the mixing was being accom-
plished. At the same time,
water department personnel
came by to disconnect the
parsonage's water line from the
church to install a separate
water meter for the parsonage.
In the process, the water was
shut off in the area of the
church building. Since the
church was located on a steep
hill, and as the remaining water
in the lines was used by
residents in the area, the church
was among the first places to
experience a negative pressure.
                                                                 The chlordane was quickly
                                                                 siphoned into the water lines
                                                                 within the church and became
                                                                 mixed with the Kool-Aid being
                                                                 prepared by women for the
                                                                 vacation bible school. Approxi-
                                                                 mately a dozen children and
                                                                 three adults experienced
                                                                 dizziness  and nausea. Fortu-
                                                                 nately, none required hospital-
                                                                 ization or medical attention.
                                                                                                             Recommended installation
                                                                                                             of hose bibb vacuum
                                                                                                             breaker backflow preventer
                                                                                                            CHAPTER TWO • 11

Chapter Three
Theory of  Backflow
and   Backsiphonage
A                                   cross-connection1 is the
                                   link or channel connecting
                              a source of pollution with a
                              potable water supply. The
                              polluting substance, in most
                              cases a liquid, tends to enter the
                              potable supply if the net force
                              acting upon the liquid acts in
                              the direction of the potable
                              supply. Two factors are therefore
                              essential for backflow.  First,
                              there must be a link between
                              the two systems. Second, the
                              resultant force must be toward
                              the potable supply.
                                  An understanding of the
                              principles of backflow  and
                              backsiphonage requires an
                              understanding of the terms
                              frequently used in their
                              discussion. Force, unless com-
                              pletely resisted, will produce
                              motion. Weight is a type of
                              force resulting from the earth's
                              gravitational attraction.
                              Pressure (P) is a force-per-unit
                              area, such as pounds per square
                              inch (psi). Atmospheric pressure is
                              the pressure exerted by the
                              weight of the atmosphere above
                              the earth.
                                  Pressure may be referred to
                              using an absolute scale, pounds
                              per square inch absolute  (psia),
                              or gage scale, pounds per
                              square inch gage (psig).
                              Absolute pressure and gage
                              pressure are related. Absolute
                              pressure is equal to the gage
                              pressure plus the atmospheric
                              pressure. At sea level the
                              atmospheric pressure is 14.7
                              psia.  Thus,
p       = p    -1-1
*- absolute   *- gage  '  ^
Pgage = Pabsolute ~ 14.7 pSl
    In essence then, absolute
pressure is the total pressure.
Gage pressure is simply the
pressure read on a gage. If there
is no pressure on the gage other
than atmospheric, the gage
would read zero. Then the
absolute pressure would be
equal to 14.7 psi which is the
atmospheric pressure.
    The term vacuum indicates
that the absolute pressure is less
than the atmospheric pressure
and that the gage pressure is
negative. A complete or total
vacuum would mean a pressure
of 0 psia or -14.7 psig. Since it
is impossible to produce a total
vacuum, the term vacuum, as
used in the text, will mean all
degrees of partial vacuum. In a
partial vacuum, the pressure
would range from slightly less
than 14.7 psia (0 psig) to
slightly greater than 0 psia
(-14.7 psig).
    Backsiphonage1 results in
fluid flow in an undesirable or
reverse direction. It is caused by
atmospheric pressure exerted on
a pollutant liquid forcing it
toward a potable water supply
system that is under a vacuum.
Backflow, although literally
meaning any type of reversed
flow, refers to the flow produced
by the differential pressure
existing between two systems
both of which are at pressures
greater than atmospheric.
Water Pressure
For an understanding of the
nature of pressure and its
relationship to water depth,
consider the pressure exerted on
the base of a cubic foot of water
at sea level. (See Fig. 1) The
average weight of a  cubic foot
of water is 62.4 pounds per
square foot gage. The base may
be subdivided into 144-square
inches with each subdivision
being subjected to a pressure of
0.433 psig.
    Suppose another cubic foot
of water were placed directly
on top of the first (See Fig. 2).
The pressure on the top surface
of the first cube which was
originally atmospheric, or
0 psig, would now be 0.433
psig as  a result of the super-
imposed cubic foot of water.
The pressure of the base of
the first cube would also be
increased by the same  amount
of 0.866 psig, or two times the
original pressure.
Pressure exerted by 1 foot of
water at sea level.



'/// ^


      0.433 psig
1See formal definition in the glossary of
the appendix

    If this process were
repeated with a third cubic foot
of water, the pressures at the
base of each cube would be
1,299 psig, 0.866 psig, and
0.433 psig, respectively. It is
evident  that pressure varies
with depth below a free water
surface;  in general each foot of
elevation change, within a
liquid, changes the pressure by
an amount equal to the weight-
per-unit area of 1 foot of the
liquid. The rate of increase for
water is 0.433 psi per foot of
    Frequently water pressure
is referred to using the terms
"pressure head" or just "head,"
and is expressed in units of feet
of water. One foot of head
would be equivalent to the
pressure produced at the base
of a column of water 1 foot in
depth. One foot of head or
1 foot of water is equal to 0.433
psig. One hundred feet of head
is equal  to 43.3 psig.
Siphon Theory

Figure 3 depicts the atmo-
spheric pressure on a water
surface at sea level. An open
tube is inserted vertically into
the water; atmospheric pres-
sure, which is 14.7 psia, acts
equally on the surface of the
water within the tube and on
the outside of the tube.
Pressure on the free surface of a
liquid at sea level.

14. 7 psia
sea level


level exactly balances the
weight of a column of water
33.9 feet in height. The
absolute pressure within the
column of water in Figure 4 at
a height of 11.5 feet is equal to
9-7 psia. This is a partial
vacuum with an equivalent
gage pressure of-5.0 psig.
    As a practical example,
assume the water pressure at a
closed faucet on the top of a
100-foot high building to be 20
psig; the pressure on the
ground floor would then  be
63.3 psig. If the pressure at the
ground were to drop suddenly
due to a heavy  fire demand in
the area to 33.3 psig, the
pressure at the  top would be
reduced to -10  psig. If the
building water  system were
airtight, the water would
remain at the level of the faucet
                                 FIGURE 4.
                                 Effect of evacuating air from a
because of the partial vacuum
created by the drop in pressure.
If the faucet were opened,
however, the vacuum would be
broken and the water level
would drop to a height of 77
feet above the ground. Thus,
the atmosphere was supporting
a column of water 23 feet high.
    Figure 5 is a diagram of an
inverted U-tube that has been
filled with water and placed in
two open containers at sea level.
    If the open containers are
placed so  that the liquid levels
in each container are at the
same height, a static state will
exist; and the pressure at any
specified level in either leg of
the U-tube will be the same.
    The equilibrium condition
is altered by raising one of the
containers so that the liquid
level in one container is 5 feet
                                 FIGURE 5.
                                 Pressure relationships in a
                                 continuous fluid system at the
                                 same elevation.
Pressure exerted by 2 feet of
water at sea level.
           0.433 psig
          0.866 psig
1See formal definition in the glossary of
the appendix
    If, as shown in Figure 4,
the tube is slightly capped and
a vacuum pump is used to
evacuate all the air from the
sealed tube, a vacuum with a
pressure of 0  psia is created
within the tube. Because the
pressure at any point in a static
fluid is dependent upon the
height of that point above a
reference line, such as sea level,
it follows that the pressure
within the tube at sea level
must still be  14.7 psia.  This is
equivalent to the pressure at the
base of a column of water 33.9
feet high and with the column
open at the base, water would
rise to fill the column to a depth
of 33.9 feet. In other words, the
weight of the atmosphere at sea
                                                  "Zero" Absolute



Sea level




or -5.0 psig

14.7 psia or
0.0 psig

                                                                                                               10.3 psia
                                                         4.7 psia
                                                                                                            CHAPTER THREE

above the level of the other. (See
Fig. 6.) Since both containers
are open to the atmosphere, the
pressure on the liquid surfaces
in each container will remain at
14.7 psia.
    If it is assumed that a static
state exists, momentarily,
within the system shown in
Figure 6, the pressure in the left
tube at any height above the
free surface in the left container
can be calculated. The pressure
at the corresponding level in the
right tube above the free surface
in the right container may also
be calculated.
    As shown in Figure 6, the
pressure at all levels in the left
tube would be less than at
corresponding levels in the right
tube. In this case, a static
condition cannot exist because
fluid will flow from the higher
pressure to the lower pressure;
the flow would be from the
right tank to the left tank. This
arrangement will be recognized
as a siphon. The crest of a
siphon cannot be higher than
33.9 feet above the upper liquid
Pressure relationships in a
continuous fluid system at
different elevations.
  8.2 psia
10.3 psia
          level, since atmosphere cannot
          support a column of water
          greater in height than 33.9 feet.
               Figure 7 illustrates how
          this  siphon principle can be
          hazardous in a plumbing
          system. If the supply valve is
          closed, the pressure in the line
          supplying the faucet is less than
          the pressure in the supply line
          to the bathtub. Flow will occur,
          therefore, through siphonage,
          from the bathtub to the open
          FIGURE 7.
          Backsiphonage in a plumbing

              Valve open
            Submerged inlet
                Valve open

                     Closed supply
    The siphon actions cited
have been produced by reduced
pressures resulting from a
difference in the water levels at
two separated points within a
continuous fluid system.
    Reduced pressure may also
be created within a fluid system
as a result of fluid motion. One
of the basic principles of fluid
mechanics is the principle of
conservation of energy. Based
upon this principle, it may be
                                 shown that as a fluid acceler-
                                 ates, as shown in Figure 8, the
                                 pressure is reduced. As water
                                 flows through a constriction
                                 such as a converging section of
                                 pipe, the velocity of the water
                                 increases; as a result, the
                                 pressure is reduced. Under such
                                 conditions, negative pressures
                                 may be developed in a pipe.
                                 The simple aspirator is based
                                 upon this principle. If this
                                 point of reduced pressure is
                                 linked  to a source of pollution,
                                 backsiphonage of the pollutant
                                 can occur.
                                 FIGURE 8.
                                 Negative pressure created by
                                 constricted flow.
                                            +30 psig
                                                       +30 psig
    One of the common
occurrences of dynamically
reduced pipe pressures is found
on the suction side of a pump.
In many cases similar to the one
illustrated in Figure 9,  the line
supplying the booster pump is
undersized or does not have
sufficient pressure to deliver
water at the rate at which the
pump  normally operates. The
rate of flow in the pipe may be
increased by a further reduction
in pressure at the pump intake.
This often results in the creation
of negative pressure at the
pump  intake. This often results
in the creation of negative
pressure. This negative pressure
may become low enough in
some cases to cause vaporization
of the water in the line. Actu-
ally, in the illustration shown,
                                 FIGURE 9.
                                 Dynamically reduced pipe

                                 From pollution             To fixture
                                                                             Booster pump
flow from the source of pollu-
tion would occur when pressure
on the suction side of the pump
is less than pressure of the
pollution source; but this is
backflaw, which will be discussed
    The preceding discussion
has described some of the
means by  which negative
pressures may be created and
which frequently occur to
produce backsiphonage. In
addition to the negative
pressure or reversed force
necessary to cause
backsiphonage and backflow,
there must also be the cross-
connection or connecting link
between the potable water
supply and the source of
pollution.  Two basic types of
connections may be created in
piping systems. These are the
solid pipe  with valved connec-
tion and the.

    Figures 10 and 11 illustrate
solid connections. This type of
connection is often installed
where it is necessary to supply
an auxiliary piping system from
the potable source. It is a direct
connection of one pipe to
another pipe or receptacle.
    Solid pipe connections  are
often made to continuous or
intermittent waste lines where
it is assumed that the flow will
be in one direction only. An
example of this would be used
cooling water from a water
jacket or condenser as shown in
Figure 11. This type of connec-
tion is usually detectable but
creating a concern on the part
Valved connections between
potable water and nonpotable

Non potable
Valved connection between
potable water and sanitary sewer.
of the installer about the
possibility of reversed flow is
often more difficult. Upon
questioning, however, many
installers will agree that the
solid connection was made
because the sewer is occasion-
ally subjected to backpressure.
    Submerged inlets are found
on many common plumbing
fixtures and are sometimes
necessary features of the fixtures
if they are to function properly.
Examples of this type of design
are siphon-jet urinals or water
closets, flushing rim slop sinks,
and dental cuspidors. Oldstyle
bathtubs and lavatories had
supply inlets below the flood
level rims, but modern sanitary
design has minimized or
eliminated this hazard in new
fixtures. Chemical and indus-
trial process vats sometimes
have submerged inlets where
the water pressure is used as an
aid in diffusion, dispersion and
agitation of the vat contents.
Even though the supply pipe
may come from the floor above
the vat, backsiphonage can
occur as it has been shown that
the siphon action can raise a
liquid such as water almost 34
feet.  Some submerged inlets
 City supply
                                          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

Backflow1, as described in this
manual, refers to reversed flow
due to backpressure other than
siphonic action. Any intercon-
nected fluid systems in which
the pressure of one exceeds the
pressure of the other may have
flow from one to the other as a
result of the pressure differen-
tial. The flow will occur from
the zone of higher pressure to
the zone of lower pressure. This
type of backflow is of concern in
buildings where two or more
piping systems are maintained.
The potable water supply is
usually under pressure directly
from the city water main.
Occasionally, a booster pump is
used. The auxiliary system is
often pressurized by a centrifical
pump, although backpressure
may be caused by gas or steam
pressure from a boiler. A
reversal in differential pressure
may occur when pressure in the
potable system drops, for some
reason, to a pressure lower than
that in the system to which the
potable water is connected.
    The most positive method
of avoiding this type of
backflow is the total or com-
plete separation of the two
systems. Other methods used
involve the installation of
mechanical devices.  All meth-
ods require routine inspection
and maintenance.
    Dual piping systems are
often installed for extra protec-
tion in the event of an emer-
gency or possible mechanical
failure of one of the  systems.
Fire protection systems are an
example. Another example is
the use of dual water connec-
tions to boilers. These installa-
tions are sometimes inter-
connected, thus creating a
health hazard.
    The illustrations in part C
of the appendix depict installa-
tions where backflow under
pressure can occur, describing
the cross-connection and the
cause of the reversed flow.
Sanitary sewer
                                                                                                  1See formal definition in the glossary of
                                                                                                  the appendix
                                                                                                           CHAPTER THREE • 15

Chapter Four
Methods  and  Devices
for the  Prevention  of
Backflow  and
Back-Si phonage
A                                 wide choice of devices
                                 exists that can be used to
                            prevent backsiphonage and
                            backpressure from adding
                            contaminated fluids or gases
                            into a potable water supply
                            system. Generally, the selection
                            of the proper device to use is
                            based upon the degree of hazard
                            posed by the cross-connection.
                            Additional considerations are
                            based upon piping size, location,
                            and the potential need to
                            periodically test the devices to
                            insure proper operation.
                                There are six basic types of
                            devices that can be used to
                            correct cross-connections: air
                            gaps, barometric loops, vacuum
                            breakers—both atmospheric
                            and pressure type, double check
                            with intermediate atmospheric
                            vent, double check valve
                            assemblies, and reduced pressure
                            principle devices. In general, all
                            manufacturers of these devices,
                            with the exception of the
                            barometric loop, produce them
                            to one or more of three basic
                            standards, thus insuring the
                            public that dependable devices
                            are  being utilized and marketed.
                            The major standards in the
                            industry are: American Society
                            of Sanitary Engineers ASSE),
                            American Water Works Associa-
                            tion (AWWA), and the Univer-
                            sity of California Foundation for
                            Cross-Connection Control and
                            Hydraulic Research.
Air Gap

Air gaps are non-mechanical
backflow preventers that are
very effective devices to be used
where either backsiphonage or
backpressure conditions may
exist. Their use is as old as
piping and plumbing itself, but
only relatively recently have
standards been issued that
standardize their design. In
general, the air gap must be
twice the supply pipe diameter
but never less than one inch.
See Figure 12.

Air gap.
  "D" -
    An air gap, although an
extremely effective backflow
preventer when used to prevent
backsiphonage and backpres-
sure conditions, does interrupt
the piping flow with corre-
sponding loss of pressure for
subsequent use. Consequently,
air gaps are primarily used at
end of the line service where
reservoirs or storage tanks are
desired. When contemplating
the use of an air gap, some
other considerations are:
(1) In a continuous piping
system, each air gap requires
the added expense of reservoirs
and secondary pumping
(2) The air gap may be easily
defeated in the event that the
"2D" requirement was purposely
or inadvertently compromised.
Excessive splash may be encoun-
tered in the event that higher
than anticipated pressures or
flows occur. The splash may be a
cosmetic or true potential
hazard—the simple solution
being to reduce the "2D"
dimension by thrusting the
supply pipe into the receiving
funnel. By so doing, the air gap
is defeated.
(3) At an air gap, we expose the
water to the surrounding air
with its inherent bacteria, dust
particles, and other airborne
pollutants or contaminants. In
addition, the aspiration effect of
the flowing water can drag down
surrounding pollutants into the
reservoir or holding tank.
(4) Free chlorine can come out of
treated water as a result of the air
gap and the resulting splash and
churning effect as the water
enters the holding tanks. This
reduces the ability of the water
to withstand bacteria contamina-
tion during long term storage.
(5) For the above reasons, air
gaps must be inspected as
frequently as mechanical
backflow preventers.  They are
not exempt from an in-depth
cross-connection control pro-
gram requiring periodic inspec-
tion of all backflow devices.
    Air gaps may be fabricated
from commercially available
plumbing components or
purchased as separate units and
integrated into plumbing and
piping systems. An example of
the use of an air gap is shown in
Figure 13.

Air gap in a piping system.
Supply piping




    Tank or reservoir

Barometric Loop

The barometric loop consists of
a continuous section of supply
piping that abruptly rises to a
height of approximately 35 feet
and then returns back down to
the originating level. It is a loop
in the piping system that
effectively protects against
backsiphonage. It may not be
used to protect against back-
    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.
Barometric loop.
Atmospheric Vacuum

These devices are among the
simplest and least expensive
mechanical types of backflow
preventers and, when installed
properly, can provide excellent
protection against back-
siphonage. They must not be
utilized to protect against
backpressure conditions.
Construction consists usually of
a polyethylene float which is
free to travel on a shaft and seal
in the uppermost position
against atmosphere with an
elastomeric disc. Water flow
lifts the float, which then causes
the disc to seal. Water pressure
keeps the float in the upward
sealed position. Termination of
the water supply will cause the
disc to drop down venting the
unit to atmosphere and thereby
opening downstream piping to
atmospheric pressure, thus
preventing backsiphonage.
Figure 15 shows a typical
atmospheric breaker.
    In general, these devices
are available in V^-inch through
3-inch size and must be
installed vertically, must not
have shutoffs downstream,
and must be installed at least
6-inches higher than the final
outlet. They cannot be tested
once they are installed in the
plumbing system, but are, for
the most part, dependable,
trouble-free devices for
backsiphonage  protection.
Atmospheric vacuum breaker.
Atmospheric vacuum breaker
typical installation.
                                FIGURE 17.
                                Atmospheric vacuum breaker in
                                plumbing supply system.
      Non flow condition
    Figure 16 shows the
generally accepted installation
requirements—note that no
shutoff valve is downstream
of the device that would
otherwise keep the atmospheric
vacuum breaker  under constant
    Figure 17 shows a typical
installation of an atmospheric
vacuum breaker  in a plumbing
supply system.
                                                                                                           CHAPTER FOUR • 17

Hose  Bibb
Vacuum Breakers

These small devices are a
specialized application of the
atmospheric vacuum breaker.
They are generally attached to
sill cocks and in turn are
connected to hose supplied
outlets such as garden hoses,
slop  sink hoses, spray outlets,
etc. They consist of a spring
loaded check valve that seals
against an atmospheric outlet
when water supply pressure is
turned on. Typical construction
is shown in Figure  18.
    When the water supply is
turned off, the device vents to
atmosphere, thus protecting
against backsiphonage condi-
tions. They should not be used
as backpressure devices. Manual
drain options are available,
together with tamper-proof
versions. A typical installation is
shown in Figure 19-
Hose bibb vacuum breaker.
Typical installation of hose bibb
vacuum breaker.
Vacuum Breakers

This device is an outgrowth of
the atmospheric vacuum
breaker and evolved in response
to a need to have an atmospher-
ic vacuum breaker that could be
utilized under constant pressure
and that could be tested in line.
A spring on top of the disc and
float assembly, two added gate
valves, test cocks, and an
additional first check, provided
the answer to achieve this
device. See Figure 20.
    These units are available in
the general configurations as
shown in Figure 20 in sizes
V2-inch through 10-inch and
have broad usage in the
agriculture and irrigation
market. Typical agricultural and
                                FIGURE 20.
                                Pressure vacuum breaker
industrial applications are
shown in Figure 21.
    Again, these devices may
be used under constant pressure
but do not protect against
backpressure conditions. As a
result, installation must be at
least 6- to 12-inches higher
than the existing outlet.
    A spill resistant pressure
vacuum breaker (SVB) is
available that is a modification
to the standard pressure
vacuum breaker but specifically
designed to minimize water
spillage. Installation and
hydraulic requirements are
similar to the standard pressure
vacuum breaker and the
devices are recommended for
internal use.
                                         Test cock

                                    First check valve
                                                                           Test cock
                                                                                                                   Gate Valve
                                                                                        3/4 inch thru 2 inches

Double Check with
Atmospheric Vent
The need to provide a compact
device in 14-inch and %-inch
pipe sizes that protects against
moderate hazards, is capable of
being used under constant
pressure and that protects
against backpressure, resulted
in this unique backflow
preventer. Construction is
basically  a double check valve
having an atmospheric vent
located between the two checks
(See Figure 22).
    Line pressure keeps the
vent closed, but zero supply
pressure or backsiphonage will
open the inner chamber to
atmosphere. With this device,
extra protection is obtained
through the atmospheric vent
capability. Figure 23 shows a
typical use of the device on a
residential boiler supply line.
Typical agricultural and
industrial application of
pressure vacuum breaker.
Double check valve with
atmospheric vent.

             1st check
2nd check
Typical residential use of double
check with atmospheric vent.
                                Automatic feed valve
                                              Air gap
                                       12" minimum above
                                        the highest outlet
                                    FIGURE 24.
                                    Double check valve.
Double Check Valve

A double check valve is
essentially two single check
valves coupled within one body
and furnished with test cocks
and two tightly closing gate
valves (See Figure 24).
    The test capability feature
gives this device a big advan-
tage over the use of two
independent check valves in
that it can be readily tested to
determine if either or both
check valves are inoperative
or fouled by debris. Each check
is spring loaded closed and
requires approximately a pound
of pressure to open.
    This spring loading
provides the ability to "bite"
through small debris and still
seal—a protection feature not
prevalent in unloaded swing
check valves. Figure 24 shows a
cross section of double check
valve complete with test cocks.
Double checks are commonly
used to protect against low to
medium hazard installations
such as food processing steam
kettles and apartment projects.
They may be used under
continuous pressure and protect
against both backsiphonage and
backpressure conditions.

At least 6"



Process tanks

— v—

- -«__


- o
- -\^—
                                                                                                           CHAPTER FOUR

Double Check Detector

This device is an outgrowth of
the double check valve and is
primarily utilized in fire line
installations. Its purpose is to
protect the potable supply line
from possible contamination or
pollution from fire line chemical
additives, booster pump fire
line backpressure, stagnant
"black water" that sits in fire
lines over extended periods of
time, the addition of "raw"
water through outside fire
pumper connections (Siamese
outlets), and the detection of
any water movement in the fire
line water due to fire line
leakage or deliberate water
theft. It consists  of two, spring
loaded check valves, a bypass
assembly with water meter and
double check valve, and two
tightly closing gate valves. See
Figure 25. The addition of test
cocks makes the device testable
Double check detector check.
to insure proper operation of
both the primary checks and
the bypass check valve. In the
event of very low fire line water
usage, (theft of water) the low
pressure drop inherent in the
bypass system permits the low
flow of water to be metered
through the bypass system. In a
high flow demand, associated
with deluge fire capability, the
main check valves open,
permitting high volume,  low
restricted flow, through the two
large spring loaded check
Residential Dual Check

The need to furnish reliable and
inexpensive backsiphonage and
backpressure protection for
individual residences resulted in
the debut of the residential dual
check. Protection of the main
potable supply from household
hazards such as home photo-
graph chemicals, toxic insect
and garden sprays, termite
control pesticides used by
exterminators, etc., reinforced,
a true need for such a device.
Figure 26 shows a cutaway of
the device.
                                FIGURE 26.
                                Residential dual check.
    It is sized for 1A-, %-, and
1-inch service lines and is
installed immediately down-
stream of the water meter. The
use of plastic check modules
and elimination of test cocks
and gate valves keeps the cost
reasonable while providing
good, dependable protection.
Typical installations are shown
in Figures 27 and 28.
                                                                 FIGURE 27.
                                                                 Residential installation.
                                                                     :••?.• 3
                                                                 FIGURE 28.
                                                                 Copper horn.
                                                                                                dual check
                                                                          11/4n meter thread female inlet with
                                                                          1" NPT thread female union outlet

Reduced Pressure
Principle Backflow

    Maximum protection is
achieved against backsiphonage
and backpressure conditions
utilizing reduced pressure
principle backflow preventers.
These devices are essentially
modified double check valves
with an atmospheric vent
capability placed between the
two checks and designed such
that this "zone" between the
two checks is always kept at
least two pounds less than the
supply pressure. With this
design criteria, the reduced
pressure principle backflow
preventer can provide protec-
tion against backsiphonage and
backpressure when both the
first and second checks become
fouled. They can be used under
constant pressure and at high
hazard installations. They are
furnished with test cocks and
gate valves to enable testing
and are available in sizes %-inch
through 10 inch.
    Figure 29A shows typical
devices representative of %-inch
through 2-inch size and  Figure
29B shows typical devices
representative of 2 Vz -inch
through 10-inch sizes.
Reduced pressure zone backflow
preventer (3/4-inch thru 2-inches).
Reduced pressure zone backflow
preventer (21/2-inches thru 1 fl-
                                                                    Reduced pressure zone
                                                          1 st check valve              2nd check valve
                                                                               Relief valve (rotated 90° for clarity)
                                                                                                           CHAPTER FOUR  •  21

    The principles of operation
of a reduced pressure principle
backflow preventer are as
    Flow from the left enters
the central chamber against the
pressure exerted by the loaded
check valve 1. The supply
pressure is  reduced thereupon
by a predetermined amount.
The pressure in the central
chamber is maintained lower
than the incoming supply
pressure through the operation
of the relief valve 3, which
discharges  to the atmosphere
whenever the central chamber
pressure approaches within a
few pounds of the inlet pres-
sure. Check valve 2 is lightly
loaded to open with a pressure
drop of 1 psi in the direction of
flow and is independent of the
pressure required to open the
relief valve. In the event that
the pressure increases down-
stream from the device, tending
to reverse the direction of flow,
check valve 2 closes, preventing
backflow. Because all valves
may leak as a result of wear or
obstruction, the protection
provided by the check valves is
not considered sufficient. If
some obstruction prevents
check valve 2 from closing
tightly, the leakage back into
the central chamber would
increase the pressure in this
zone, the relief valve would
open, and flow would be
discharged to the atmosphere.
    When the supply pressure
drops to  the minimum differen-
tial required to operate the
relief valve, the pressure in  the
central chamber should be
atmospheric. If the inlet
pressure  should become less
than atmospheric pressure,
relief valve 3 should remain
fully open to the atmosphere to
discharge any water which may
be caused to backflow as a
result of backpressure and
leakage of check valve 2.
    Malfunctioning of one or
both of the check valves or relief
valve should always be indi-
cated by a discharge of water
from the relief port. Under no
circumstances should plugging
of the relief port be permitted
because the device depends
upon an open port for safe
operation. The pressure loss
through the device may be
expected to average between
10 and  20 psi within the
normal  range of operation,
depending upon the size and
flow rate of the device.
    Reduced pressure principle
backflow preventers are
commonly installed on high
hazard installations such as
plating plants, where they
would protect against primarily
backsiphonage potential, car
washes where they would
protect against backpressure
conditions, and funeral parlors,
hospital autopsy rooms, etc.
The reduced pressure principle
backflow preventer forms the
backbone of cross-connection
control programs. Since it is
utilized to protect against high
hazard installations, and since
high hazard installations are the
first consideration in protecting
public health and safety, these
devices are installed in large
quantities over a broad range of
plumbing and water works
installations. Figures 31 and 32
show typical installations of
these devices on high hazard
Reduced pressure zone backflow
preventer — principle of operation.
                                               Reversed direction
                                                   of flow
                                 FIGURE 31.
                                 Plating plant installation.
                                                                  Reduced pressure principle backflow preventer
                                                                  FIGURE 32.
                                                                  Car wash installation.
                                                Reduced pressure principle
                                                   backflow preventer

Typical bypass configuration
reduced pressure principle
               Reduced pressure
                principle device
                     Reduced pressure principle device

                                     Air gap
                                |  [ Drain

Note: Devices to be set a mm. of 12" and a max. of 30" from the floor and 12" from any wall.
                                                                    FIGURE 34.
                                                                    Typical installation reduced
                                                                    pressure principle device
                                                                    horizontal illustration.
                                                                                 1          ^
                                                                                 1	I  LJ
                                   Reduced pressure
                                    principle device
                          T,—n	n	n_.   T


Typical installation double check
valve horizontal and vertical
                                  FIGURE 37.
                                  Typical installation residential dual
                                  check with straight set and
                                      Double check valve

                 Water meter
                                                12" min. 30" max.
                                 Double check valve
                                   (unit to be set at a height
                                   that permits ready access
                                   for testing and service)
Copperhorn with
  water meter
                                                                                                             3/4n ball valve
                                                                                                               dual check
                                                                                                                        Copperhorn with
                                                                                                                          water meter

      Note: Vertical installation only to be used if horizontal
      installation cannot be achieved.
                                                                                                             3/4n ball valve
                                                                                                                  3/4n K-copper

Chapter Five
Testing   Procedures
for  Backflow
                                  Rior to initiating a test of
                                  my backflow device, it is
                              recommended that the follow-
                              ing procedures be followed:

                              1. Permission be obtained from
                              the owner, or his representative,
                              to shut down the water supply.
                              This is necessary to insure that
                              since all testing is accomplished
                              under no-flow conditions, the
                              owner is aware that his water
                              supply will be temporarily shut
                              off while the testing is being
                              performed. Some commercial
                              and industrial operations
                              require constant and uninter-
                              rupted water supplies for
                              cooling, boiler feed, seal pump
                              water, etc. and water  service
                              interruption cannot be tolerat-
                              ed. The water supply  to
                              hospitals and continuous
                              process industries cannot be
                              shut off without planned and
                              coordinated shut downs. The
                              request to shut down the water
                              supply is therefore a necessary
                              prerequisite to protect the
                              customer as well as limit the
                              liability of the tester.
                                  Concurrent with  the
                              request for permission to shut
                              off the water, it is advisable to
                              point out to the owner, or his
                              representative, that while the
                              water is shut off during the test
                              period, any inadvertent use of
                              water within the building will
                              reduce the water pressure to
                              zero. Backsiphonage could
                              result if unprotected cross-
connections existed which
would contaminate the building
water supply system. In order
to address this situation, it is
recommended that the owner
caution the inhabitants of the
building not to use the water
until the backflow test is
completed and the water
pressure restored. Additional
options available to the building
owner would be  the installation
of two backflow  devices in
parallel that would enable a
protected bypass flow around
the device to be tested. Also, if
all water outlets  are protected
within the building with
"fixture outlet protection"
backflow devices, cross-
connections would not create a
problem in the event of
potential backsiphonage
conditions occurring while
devices are tested, or for any
other reason.
2. Determine the type of device
to be tested i.e., double check
valve or reduced pressure
principle device.
3. Determine the flow direc-
tion. (Reference directional flow
arrows or wording provided by
the manufacturer on the
4. Number the test cocks, bleed
them of potential debris, and
assemble appropriate test cock
adapters and bushings that may
be required.
5. Shut off the downstream
(number 2) shut-off valve. (Ref.
Item (1) above.)
6. Wait several moments prior
to hooking up the test kit hoses
when testing a reduced pressure
principle device. If water exits
the relief valve,  in all likelihood,
the first check valve is fouled
and it is impractical to proceed
with the testing until the valve
is serviced. This waiting period
is not necessary when testing
double check valves.
7. Hook up the test kit hoses in
the manner appropriate to the
device being tested and the
specific test being performed.
    Test personnel are cau-
tioned to be aware and follow
local municipal, county, and
state testing requirements and
guidelines as may be dictated
by local authority. The follow-
ing test procedures are guide-
lines for standard, generally
acceptable test procedures
but may be amended, superced-
ed, or modified by local
                                                                                                    CHAPTER FIVE  •  25

Test Equipment
    Er field testing of reduced
   x ressure principle backflow
preventers and double check
valve assemblies, a differential
pressure test gauge is utilized
having a 0 to 15 psi range and
a working pressure of 500 psi.
Appropriate length of hoses
with necessary fittings accom-
pany the test gauge. Several
manufactured test kits are
commercially available that
incorporate the differential
gauge, hoses, and fittings and
are packaged for ease of
portability and come with
protective enclosures or straps
for hanging. Calibrated water
columns are commercially
available that are portable and
come with carrying cases.
    It is important that all test
equipment be periodically
checked for calibration.
Pressure Vacuum
(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

Method 1
Using a differential pressure

Test 1 Test the internal check
valve for tightness of 1 psid in
the direction of flow.
1.  With the valve body under
    pressure, (number 2 shut-
    off valve closed and
                                FIGURE 38.
          Air inlet valve canopy
    number 1 shut-off valve
    open) bleed test cocks
    number 1 and number 2.
2.  Hook up the high pressure
    hose to number 1 test cock
    and the low pressure hose
    to number 2 test cock.
3.  Bleed the high pressure
    hose, and low pressure
    hose, in that order, and
    close the  test kit needle
    valves slowly.
4.  Record the differential
    pressure on the gauge. A
    reading of 1 psid is
    acceptable to insure a  tight
    check valve.
Test 2 Test the air inlet valve
for a breakaway of 1 psi.
1.  Connect the high pressure
    hose to test cock number 2,
    and bleed the high pressure
2.  Shut off number 1  shut-off
3.  Slowly open the bleed valve
    of the test kit,  and observe
    and record the psi when
    the air inlet poppet opens.
    This should be a minimum
    of 1 psi. Restore the valve
    to normal service.
Method 2
Using a water column sight
tube and 90 degree elbow
fitting with bleed needle
Test 1 Test the internal check
valve for tightness of 1 psid in
the direction of flow.
1.  Assemble sight tube to test
    cock number 1. Open test
    cock and fill the tube to a
    minimum of 36-inches of
    water height.
2.  Close number 1 shut-off
3.  Open test cock number 2.
    The air inlet valve should
    open and discharge water
    through number 2 test
4.  Open number 1  test cock.
    The sight tube level of
    water should drop slowly
    until it stabilizes. This
    point should be a mini-
    mum of 28-inches of water
    column which equals 1 psi.

Test 2 Test the air inlet valve
for a breakaway of 1 psi.
1.  Assemble sight tube to
    test cock number 2. Open
    test cock number 2 and fill
    the tube to a minimum of
    36-inches of water height.
2.  Close number 1 shut-off
3.  Bleed water slowly from
    the number 2 test cock
    bleed needle and observe
    the water column height as
    it drops.
4.  At the point when the air
    inlet valve pops open,
    record the height of the
    water column. This point
    should be a minimum of
    28-inches of water column
    which equals Ipsi.
Restore the valve to normal
Reduced Pressure
Principle Backflow
(Figure 39)
Field testing of a reduced
pressure principle backflow
preventer is accomplished
utilizing a differential pressure
gauge. The device is tested for
three optional characteristics:
i.e., (1) the first check valve is
tight and maintains a minimum
of 5 psi differential pressure,
(2) the second check valve is
tight against backpressure  and
(3) the relief valve opens at a
minimum of 2 psi below inlet
supply pressure. Testing is
performed as follows:
Step 1 Test to insure that the
first check valve is tight and
maintains  a minimum pressure
of 5 psi differential pressure.
1.  Verify that number 1 shut-
    off valve is open. Close
    number 2 shut-off valve.
    If there is no drainage
    from the relief valve it is
    assumed that the first
    check is tight.
2.  Close  all test kit valves.
3.  Connect the high pressure
    hose to test cock number 2.
4.  Connect the low pressure
    hose to test cock number 3.
5.  Open test cocks number 2
    and number 3.
6.  Open high side bleed
    needle valve on test kit
    bleeding the air from the
    high hose. Close the high
    side bleed needle valve.
7.  Open the low side  bleed
    needle valve on test kit
    bleeding air from the low
    hose. Close the low side
    bleed  needle valve. Record
    the differential gauge
    pressure. It should  be a
    minimum of 5 psid.

Step 2 Test to insure that the
second check is tight against
backpressure. (Figure 40)
I.   Leaving the hoses hooked
    up as in the conclusion of
    Step 1 above, connect the
    bypass hose to test cock
    number 4.
2.   Open test cock number 4,
    the high control needle
    valve and the bypass hose
    control needle valve on the
    test kit. (This supplies high
bypass hose
                                            Bypass hose
pressure water downstream
of check valve number 2.)
If the differential pressure
gauge falls off and water
comes out of the relief
valve, the second check is
recorded as leaking. If the
differential pressure gauge
remains steady, and no
water comes out of the
relief valve, the second
check valve is considered
3.  To check the tightness of
    number 2 shut-off valve,
    leave the hoses hooked up
    the same as at the conclu-
    sion of Step 2 above, and
    then close test cock
    number 2. This stops the
    supply of any high pressure
    water downstream of check
    valve number 2. If the
    differential pressure gauge
    reading holds steady, the
    number 2 shut-off valve  is
    recorded as being tight. If
    the differential pressure
    gauge drops to zero, the
    number 2 shut-off valve  is
    recorded as leaking.
    With a leaking number 2
shut-off valve, the device is, in
most cases, in a flow condition
and the previous readings taken
are invalid. Unless a non-flow
condition can be achieved,
either through the operation  of
an additional shut-off down-
stream, or the use of a tempo-
rary compensating bypass hose,
accurate  test results will not be
Step 3 To check that the relief
valve opens at a minimum
pressure  of 2 psi below inlet
1.  With the hoses hooked up
    the same as at the conclu-
    sion of Step #2 (3) above,
    slowly open up the low
    control needle valve on the
    test  kit and record the
    differential pressure gauge
    reading at the point when
    the water initially starts to
    drip from the relief valve
    opening. This pressure
    reading should not be
    below 2 psid.
                                                                  This completes the
                                                             standard field test for a reduced
                                                             pressure principle backflow
                                                             preventer. Before removal of the
                                                             test equipment, the tester
                                                             should insure that he opens
                                                             number 2 shut-off valve
                                                             thereby reestablishing flow.
                                                             Also, the test kit should be
                                                             thoroughly drained of all water
                                                             to prevent freezing by opening
                                                             all control needle valves and
                                                             bleed needle valves.
                                                                  All test data should be
                                                             recorded on appropriate forms.
                                                             (Ref: sample Page 45)

                                                             Note: The steps outlined above may
                                                             vary in sequence depending upon local
                                                             regulations and/or preferences.
                                                                                                             CHAPTER FIVE • 27

Double Check Valve
(Figure 41)
Some field test procedures for
testing double check valve
assemblies require that the
number 1 shut-off valve be
closed to accomplish the test.
This procedure may introduce
debris such as rust and tubercu-
lin into the valve that will
impact against check valve
number 1 or number 2 and
compromise the sealing quality.
This potential problem should
be considered prior to  the
selection of the appropriate test
    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.
                                                         Bypass hose
7.  Record the differential
    gauge pressure reading.
    It should be a minimum
    of 1 psid.

8.  Disconnect the hoses.

Step 2 Checking check valve
number 2.
1.  Connect the high hose to
    test cock number 3.
2.  Connect the low hose to
    test cock number 4.
3.  Open test cocks number 3
    and 4.
4.  Open high side bleed
    needle valve on test kit
    bleeding the air from the
    high hose. Close  the high
    side bleed needle valve.
5.  Open low side bleed needle
    valve on test kit  bleeding
    the  air from the low hose.
    Close the low side bleed
    needle valve.
6.  Record the differential
    gauge pressure reading.
    It should be a minimum
    of 1 psid.
7.  Disconnect the hoses.
    To check tightness of
number 2 shut-off valve, both
the check valves must be tight
and holding a minimum of
1 psid. Also, little or no
fluctuation of inlet supply
pressure can be tolerated.
    The testing is performed as
1.  Connect the high hose to
    number 2 test cock.
2.  Connect the low hose to
    number 3 test cock.
3.  Connect the bypass hose to
    number 4 test cock.
4.  Open test cocks numbers
    2, 3, and 4.
5.  Open high side bleed
    needle valve on test kit
    bleeding the air from the
    high hose. Close the high
    side bleed needle valve.
6.  Open low side bleed needle
    valve on test kit bleeding
    the air from the low hose.
    Close the low side bleed
    needle valve.
7.  The differential gauge
    pressure should read a
    minimum of 1 psid.
8.  Open the high side control
    needle valve and the bypass
    hose control needle valve
    on the test kit. (This
    supplies high pressure
    water downstream of check
    valve number 2).
9-  Close test cock number 2.
    (This stops the supply of
    any high pressure water
    downstream of number 2
    check valve), If the
    differential pressure gauge
    holds steady, the number 2
    shut-off valve is recorded as
    being tight. If the differen-
    tial pressure gauge drops to
    zero, the number 2 shut-off
    valve is recorded as leaking.

                    Duplex gauge
                                          Individual Bourdon gages mounted on a board
                               Bypass hose
           High side hose I   \ Low side hose
                                       Bypass hose
                                             High side hose       Low side hose
    With a leaking number 2
shut-off valve, the device is, in
most cases, in a flow condition,
and the previous test readings
taken are invalid. Unless a non-
flow condition can be achieved,
either through the operation of
an additional shut-off down-
stream, or the use of a tempo-
rary compensating bypass hose,
accurate test results will not be
    This completes the
standard field test for a double
check valve assembly. Prior to
removal of the test equipment,
the tester should insure that he
opens number 2 shut-off valve
thereby reestablishing flow. All
test data should be recorded on
appropriate forms and the  test
kit drained of water.
Method 2
Utilizing "Duplex Gauge" or
individual  bourdon gauges,
requires closing number 1
shut-off. (Figure 42)
Step 1 checking check valve
number 1
1.   Connect the high hose to
    test cock number 2.
2.   Connect the low hose to
    test cock number 3.
3.   Open test cocks number 2
    and number 3.
4.   Close  number 2 shut-off
    valve; then close number  1
    shut-off valve.
5.   By means of the high side
    needle valve, lower the
    pressure at test cock
    number 2 about 2 psi
    below the pressure at test
    cock number  3. If this
    small  difference can be
    maintained, then check
    valve number 1 is reported
    as "tight". Proceed to Step
    number 2. If the small
    difference cannot be
    maintained, proceed  to
    Step number  3.
Step 2 checking check valve
number 2.
    Proceed exactly the same
test procedure as in Step
number 1, except that the
high hose is connected to test
cock number 3 and the low
hose connected to test cock
number 4.
Step 3
1.  Open shut-off valve
    number 1 to repressurize
    the assembly.
2.  Loosely attach the bypass
    hose to test cock number 1,
    and bleed from the gauge
    through the bypass hose
    by opening the low side
    needle valve to eliminate
    trapped air. Close low side
    needle valve. Tighten
    bypass hose. Open test
    cock number 1.
3.  Close number 1 shut-off
4.  By loosening the low side
    hose at test cock number 3,
    lower the pressure in the
    assembly about 10 psi
    below normal line
5.  Simultaneously open both
    needle valves. If the check
    valve is holding tight the
    high pressure gauge will
    begin to drop while the
    low pressure gauge will
    increase. Close needle
    valves. If the gauge shows
    that a small (no more than
    5 psi) backpressure is
    created and held, then the
    check valve is reported as
    tight. If the check valve
    leaks, a pressure differential
    is not maintained as both
    gauges tend to equalize or
    move back towards each
    other, then the check valve
    is reported as leaking.
    With both needle valves
    open enough to keep the
    needles on the gauge
    stationary, the amount of
    leakage is visible as the
    discharge from the
    upstream needle valve.
                                                                                                           CHAPTER FIVE  •  29

Chapter Six
Administration  of
a  Cross-Connection
Control  Program
                           Air conditioning cooling tower
Post mix
            Backflow preventer
             with intermediate
             atmospheric vent
               Laboratory faucet double
                 check valve with
              intermediate vacuum breaker
                  Laboratory Sinks
                    Slop sink
                    Reduced pressure
          Dedicated  A  |°ne backflow
Reduced pressure zone
 backflow preventer
             pressure zone
                                  pressure zone
             Double check valve
                 preventer f Cafeteria
             Reduced pressure,,
              zone backflow/
                   Containment device
    Under the provisions of the
    Safe Drinking Water Act of
1974, the Federal Government
has established, through the
EPA (Environmental Protection
Agency), national standards of
safe drinking water. The states
are responsible for the enforce-
ment of these standards as well
as the supervision of public
water supply systems and the
sources of drinking water. The
water purveyor (supplier) is held
responsible for compliance to
the provisions of the Safe
Drinking Water Act, to include
a warranty that water quality
provided by his operation is in
conformance with the EPA
standards at the source, and is
delivered to the customer
without the quality being
compromised as a result of its
delivery through the distribu-
tion system. As specified in the
Code of Federal Regulations
(Volume 40, Paragraph 141.2,
Section (c)) "Maximum contam-
inant level, means the maxi-
mum permissible level of a
contaminant in water which is
delivered to the free flowing
outlet of the ultimate user of a
public water system, except in
the case of turbidity where the
maximum permissible level is
measured at the point of entry
to  the distribution system.
Contaminants added to the
water under circumstances
controlled by the user, except
those resulting from corrosion
of piping and plumbing caused
by water quality, are excluded
from this definition."
   Figure 43 depicts several
options that are open to a water
purveyor when considering
cross-connection protection to
commercial, industrial, and
residential customers. He may
elect to work initially on the
"containment" theory. This
approach utilizes a minimum of
backflow devices and isolates
the customer from the water
main. It virtually insulates the
customer from potentially
contaminating or polluting the
public water supply system.
While it is recognized that
"containment" does not protect
the customer within his
building, it does effectively
remove him from possible
contamination to the public
water supply system. If the
water purveyor elects to protect
his customers on a domestic
internal protective basis and/or
"fixture outlet protective basis,"
then cross-connection control
protective devices are placed at
internal high hazard locations as
well as at all locations where
cross-connections exist at the
"last free-flowing outlet." This
approach entails extensive
cross-connective survey work on
behalf of the water superinten-
dent as well as constant policing
of the plumbing within each
commercial, industrial and
residential account. In large
water supply systems, fixture
outlet protection cross-
connection control philosophy,
in itself, is a virtual impossibility
to achieve and police due to the
quantity of systems involved,
the complexity of the plumbing
systems inherent in many
industrial sites, and the fact that
many plumbing changes are
made within industrial and
commercial establishments that
do not require the water depart-
ment to  license or otherwise
endorse or ratify when contem-
plated or completed.
    In addition, internal
plumbing cross-connection
control survey work is generally
foreign to the average water

                                                                  Method  of Action
purveyor and is not normally a
portion of his job description or
duties. While it is admirable for
the water purveyor to accept
and perform survey work, he
should be aware that he runs
the risk of additional liability in
an area that may be in conflict
with plumbing inspectors,
maintenance personnel and
other public health officials.
    Even where extensive
"fixture outlet protection,"
cross-connection control
programs are in effect through
the efforts of an aggressive and
thorough water supply cross-
connection control program,
the water authorities should also
have an active "containment"
program in order to address the
many plumbing changes that
are made and that are inherent
within commercial and industri-
al establishments. In essence,
fixture outlet protection
becomes  an extension beyond
the "containment" program.
    Also, in order for the
supplier of water to provide
maximum protection of the
water distribution system,
consideration should be given to
requiring the owner of a
premise (commercial, industrial,
or residential) to provide  at his
own expense, adequate proof
that his internal water system
complies with the local or state
plumbing code(s). In addition,
he may be required to install,
have tested, and maintain, all
backflow protection devices  that
would be required—at his own
    The  supplier of water
should have the right of entry
to determine degree of hazard
and the existence of cross-
connections in order to protect
the potable water system. By so
doing he can assess the overall
nature of the facility and its
potential impact on the water
system (determine degree of
hazard], personally see actual
cross-connections that could
contaminate the water system,
and take appropriate action to
insure the elimination of the
cross-connection or the installa-
tion of required backflow devices.
    To assist the water purvey-
or in the total administration
of a cross-connection control
program requires that all public
health officials, plumbing
inspectors, building managers,
plumbing installers, and
maintenance men participate
and share in the responsibility
to protect the public health and
safety of individuals from cross-
connections  and contamination
or pollution  of the public water
supply system.
Dedicated Line

Figure 43 also depicts the use
of a "dedicated" potable water
line. This line initiates immedi-
ately downstream of the water
meter and is "dedicated"  solely
for human consumption i.e.,
drinking fountains, safety
showers, eye wash stations, etc.
It is very important that this
piping be color coded through-
out in accordance with local
plumbing regulations, flow
direction arrows added, and the
piping religiously policed to
insure that no cross-connections
to other equipment or piping
are made that could compro-
mise water quality. In the event
that it is felt that policing of
this line cannot be reliably
maintained or enforced, the
installation of a containment
device on this line should be a
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
(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
(3) Place written notices of the
pending cross-connection
control program in the local
newspaper, and have the local
radio station make announce-
ments about the program as a
public service notice.
(4) Send employees who will
administer  the program, to a
course, or courses, on backflow
tester certification, backflow
survey courses, backflow device
repair courses, etc.
(5) Equip the water authority
with backflow device test kits.
(6) Conduct meeting(s) with
the local plumbing inspection
people, building inspectors, and
licensed plumbers in the area
who will be active in the
inspection, installations and
repair of backflow devices.
Inform them of the intent of the
program and the part that they
can play in the successful
implementation of the program.
(7) Prior to initiating a survey
of the established commercial
and industrial installations,
prepare a list of these establish-
ments from existing records,
then prioritize the degree of
hazard that they present to the
water system, i.e., plating
plants, hospitals, car wash
facilities, industrial metal
finishing and fabrication,
mortuaries, etc. These will be
the initial facilities  inspected for
cross-connections and will be
followed by less hazardous
(8) Insure that any new
construction plans  are reviewed
by the water authority to assess
the degree of hazard and insure
that the proper backflow
preventer is installed concurrent
with the potential degree of
hazard that the facility presents.
(9) Establish a residential
backflow protection program that
will automatically insure that a
residential dual check backflow
device is installed automatically at
every new residence.
(10) As water meters are
repaired  or replaced at residen-
ces, insure that a residential
dual check backflow preventer
is set with the new or reworked
water meter. Be sure to have
the owner address thermal
expansion provisions.
                                                                                                               CHAPTER SIX • 31

(11) Prepare a listing of all
testable backflow devices in the
community and insure that
they are tested by certified test
personnel at the time intervals
consistent with the local cross-
connection control ordinance.
(12) Prepare and submit
testing documentation of
backflow devices to the State
authority responsible for
monitoring this data.
(13) Survey all commercial and
industrial facilities and require
appropriate backflow protection
based upon the containment
philosophy and/or internal
protection and fixture outlet
protection. Follow up to insure
that the recommended devices
are installed and tested on both
an initial basis and a periodic
basis consistent with the cross-
connection control ordinance.
    The surveys should be
conducted by personnel
experienced in commercial and
industrial processes. The owners
or owners representatives,
should be questioned as to what
the water is being used for in
the facility and what hazards
the operations may present to
the water system (both within
the facility and to the water
distribution system) in the
event that a backsiphonage or
backpressure condition were to
exist concurrent with a non-
protected cross-connection. In
the event that experienced
survey personnel are not
available within the water
authority to conduct the survey,
consideration should be given
to having a consulting firm
perform the survey on behalf of
the water department.
Control Survey

Coss-connection control
     survey work should only
be performed by personnel
knowledgeable about commer-
cial and industrial potential
cross-connections as well as
general industrial uses for both
potable and process water. If
"containment" is the prime
objective of the survey, then
only sufficient time need be
spent in the facility to deter-
mine the degree of hazard
inherent within the facility or
operation. Once this is deter-
mined, a judgment can be
made by the cross-connection
control inspector as to what
type of backflow protective
device will be needed at the
potable supply entrance, or
immediately downstream of the
water meter. In the event that
the cross-connection control
program requires "total"
protection to the last free
flowing outlet, then the survey
must be conducted in depth to
visually inspect for all cross-
connections within the facility
and make recommendations
and requirements for fixture
outlet protective devices,
internal protective devices, and
containment devices.
    It is recommended that
consideration be given to the
following  objectives when
performing a cross-connection
control survey:
(1) Determine if the survey will
be conducted with a pre-
arranged appointment or
(2) Upon entry, identify
yourself and the purpose of the
visitation and request to see the
plant manager, owner, or
maintenance supervisor in order
to explain the purpose of the
visit and why the cross-
connection survey will be of
benefit to him.
(3) Ask what processes are
involved within the facility and
for what purpose potable water
is used, i.e., do the boilers have
chemical additives? Are air
conditioning cooling towers in
use with chemical additives? Do
they use water savers with
chemical additives? Do they
have a second source of water
(raw water from wells, etc.) in
addition to the potable water
supply? Does the process water
cross-connect with potentially
hazardous chemical etching
tanks, etc.?
(4) Request "as-built" engineer-
ing drawings of the potable
water supply in order to trace
out internal potable lines and
potential areas of cross-
(5) Initiate the survey by
starting at the potable entrance
supply (the water meter in most
cases) and then  proceed with
the internal survey in the event
that total  internal protective
devices and fixture outlet
protective devices are desired.
(6) Survey the plant facilities
with the objective of looking for
cross-connections at all potable
water outlets such  as:
    Hose bibbs
    Slop sinks
    Wash room facilities
    Cafeteria and kitchens
    Fire protection and
        Siamese outlets
    Irrigation outlets
    Boiler rooms
    Mechanical  room
    Laundry facilities
    Production floor
(7) Make a sketch  of all areas
requiring backflow protection
(8) Review with the host what
you have found and explain the
findings to him. Inform him
that he will receive a written
report documenting the
findings together with a written
recommendation for corrective
action. Attempt to answer all
questions at this time. Review
the findings with the owner or
manager if time and circum-
stances permit.
(9) Document all findings and
recommendations prior to
preparing the written report.
Include as many sketches or
photos with the final report as
possible. If the located cross
connection(s) cannot be
eliminated, state the generic
type of backflow preventer
required at each cross connec-
tion found.
(10) Consider requiring or
recommending compliance of
the survey findings within a
definitive time frame, (if
appropriate authority is in

Chapter Seven
Control  and  Backflow
Prevention  Program
'~T~the successful promotion of
 _L a cross-connection control
and backflow prevention
program in a municipality
will be dependent upon legal
authority to conduct such a
program. Where a community
has adopted a modern plumb-
ing code, such as the National
Plumbing Code, ASA A40.8-
1955, or subsequent revisions
thereof, provisions of the code
will govern backflow and
cross-connections. It then
remains to provide an ordinance
that will establish a program
of inspection for an elimination
of cross- and backflow connec-
tions  within the community.
Frequently authority for such
a program may  already be
possessed by the water depart-
ment or water authority. In
such cases no further document
may be needed.  A cross-
connection control ordinance
should have at least three
basic  parts.
1.  Authority for establish-
   ment of a program.
2.  Technical provisions
   relating to eliminating
   backflow and cross-
3.  Penalty provisions for
   The following model
program is suggested for
municipalities who desire to
adopt a cross-connection
control ordinance. Communi-
ties adopting ordinances should
check with State health officials
to assure conformance with
State codes. The form of the
ordinance should comply with
local legal requirements and
receive legal adoption from the
                                    CROSS CONNECTION CONTROL
                                           MODEL PROGRAM
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-
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,
                                                                                        CHAPTER SEVEN

III. Responsibility
    The Director of Municipal Services shall be responsible for the
protection of the public potable water distribution system from
contamination or pollution due to the backflow or backsiphonage
of contaminants or pollutants through the water service connec-
tion. If, in the judgment of the Director of Municipal Services, an
approved backflow device is required at the city's water service
connection to any customer's promises, the Director, or his
delegated agent, shall give notice in writing to said customer to
install an approved backflow prevention device at each service
connection to his premises. The customer shall, within 90 days
install such approved device, or devices, at his  own expense, and
failure or refusal, or inability on the part of the customer to install
said device or devices within ninety (90) days,  shall constitute a
ground for discontinuing water service to the premises until such
device or devices have been properly installed.

IV  Definitions

A.  Approved
    Accepted by the Director of Municipal Services as meeting an
applicable specification stated or cited in this regulation, or as
suitable for the proposed use.
B.  Auxiliary Water Supply
    Any water supply, on or available, to the premises other than
the purveyor's approved public potable water  supply.
C.  Backflow
    The flow of water or other liquids,  mixtures or substances,
under positive or reduced pressure in the distribution pipes of a
potable water supply from any source other than its intended
D.  Backflow Preventer
    A device or means designed to prevent backflow or
backsiphonage. Most commonly categorized as air gap, reduced
pressure principle device, double check valve assembly, pressure
vacuum breaker, atmospheric vacuum breaker, hose bibb vacuum
breaker, residential dual check, double check with intermediate
atmospheric vent, and barometric loop.
D. 1 Air Gap
    A physical separation sufficient to prevent backflow between
the free-flowing discharge end of the potable water system and any
other system. Physically defined as a distance equal to twice the
diameter of the supply side pipe diameter but  never less than one
(1) inch.
D.2 Atmospheric Vacuum Breaker
    A device which prevents backsiphonage by creating an
atmospheric vent when there is  either a negative pressure or
subatmospheric pressure in a water system.
D.3 Barometric Loop
    A fabricated piping arrangement rising at least thirty five (35)
feet at its topmost point above the highest fixture it supplies. It is
utilized in water supply systems to protect against backsiphonage.
D.4 Double Check Valve Assembly
    An assembly  of two (2) independently operating spring loaded
check valves with tightly closing shut off valves on each side of the
check valves, plus properly located test cocks for the testing of each
check valve.
D.5 Double Check Valve with Intermediate Atmospheric Vent
    A device having two (2) spring loaded check valves separated
by an atmospheric vent chamber.
D.6 Hose Bibb Vacuum Breaker
    A device which is permanently attached to a hose bibb and
which acts as an atmospheric vacuum breaker.
D.7 Pressure Vacuum Breaker
    A device containing one or two independently operated spring
loaded check valves and an independently operated spring loaded
air inlet valve located on the discharge side of the check or checks.
Device includes tightly closing shut-off valves on each side of the
check valves and properly located  test cocks for the testing of the
check valve(s).
D.8 Reduced Pressure Principle Backflow Preventer
    An assembly  consisting of two (2) independently operating
approved check valves with an automatically operating differential
relief valve located between the two (2) check valves, tightly
closing shut-off valves on each side of the check valves plus
properly located test  cocks for the testing of the check valves and
the relief valve.
D.9 Residential Dual Check
    An assembly  of two (2) spring loaded, independently operat-
ing check valves without tightly closing shut-off valves and test
cocks. Generally employed immediately downstream of the water
meter to act as a containment device.
E.  Backpressure
    A condition in which the owners system pressure is greater
than the suppliers system pressure.
F.  Backsiphonage
    The flow of water or other liquids, mixtures or substances into
the distribution pipes of a potable water supply system from any
source other than its  intended source caused by the sudden
reduction of pressure in the potable water supply system.
G  Commission
    The State of (
) Control Commission.

H. Containment
    A method of backflow prevention which requires a backflow
prevention preventer at the water service entrance.
I.   Contaminant
    A substance that will impair the quality of the water to a
degree that it creates a serious health hazard to the public leading
to poisoning or the spread of disease.
J.   Cross-Connection
    Any actual or potential connection between the public water
supply and a source of contamination or pollution.
K. Department
    City of (        ) Water Department.
L.  Fixture Isolation
    A method of backflow prevention in which a backflow
preventer is located to correct a cross connection at an in-plant
location rather than at a water service entrance.
M. Owner
    Any person who has legal title to, or license to operate or
habitat in, a property upon which a cross-connection inspection is
to be made or upon which a cross-connection is present.
N. Person
    Any individual, partnership, company, public or private
corporation, political subdivision or agency of the State Depart-
ment, agency or instrumentality  or the United States  or any other
legal entity.
O. Permit
    A document issued by the Department which allows the use of
a backflow preventer.
P   Pollutant
    A foreign substance, that if permitted to get into the public
water system, will degrade its quality so as to constitute a moder-
ate hazard, or impair the usefulness or quality of the water to a
degree which does not create an actual hazard to the public health
but which does adversely and unreasonably effect such water for
domestic use.
Q. Water Service Entrance
    That point in the owners water system beyond  the sanitary
control of the District; generally considered to be the  outlet end of
the water meter and always before any unprotected branch.
R.  Director of Municipal Services
    The Director, or his delegated representative in charge of the
(       ) Department of Municipal Services, is invested with the
authority and responsibility for the implementation  of a cross-
connection control program and  for the enforcement of the
provisions of the Ordinance.
Y  Administration

A.  The Department will operate a cross-connection control
program, to include the keeping of necessary records, which fulfills
the requirements of the Commission's Cross-Connection Regula-
tions and is approved by the Commission.
B.  The Owner shall allow his property to be inspected for possible
cross-connections and shall follow the provisions of the
Department's program and the Commission's Regulations if a
cross-connection is permitted.
C.  If the Department requires that the public supply be protected
by containment, the Owner shall be responsible for water quality
beyond the outlet end of the containment device and should utilize
fixture outlet protection for that purpose.
    He may utilize public health officials, or personnel from the
Department, or their delegated representatives, to assist him in the
survey of his facilities and to assist him in the selection of proper
fixture outlet devices, and the proper installation of these devices.

VI. Requirements

A.  Department
    1.  On new installations, the Department will provide  on-
site evaluation  and/or inspection of plans in order to determine
the type of backflow preventer, if any, that will be required,  will
issue permit, and perform inspection and testing. In any case, a
minimum of a dual check valve will be required in any new
    2.  For premises existing prior to the start of this program,
the Department will perform evaluations and inspections of plans
and/or premises and inform the owner by letter of any corrective
action deemed necessary, the method of achieving the correction,
and the time allowed for the correction to be made. Ordinarily,
ninety (90) days will be allowed, however, this time period may be
shortened depending upon the degree of hazard involved and the
history of the device(s) in question.
    3.  The Department will not allow any cross-connection to
remain unless it is protected by an approved backflow preventer for
which a permit has been issued and which will be regularly tested
to insure satisfactory operation.
    4.  The Department shall inform the Owner by letter,  of
any failure to comply, by the time of the first re-inspection. The
Department will allow an additional fifteen (15) days  for the
correction. In the event the Owner fails to comply with the
necessary correction by the time of the second re-inspection, the
Department will inform the Owner by letter, that the water
service to the Owner's premises will be terminated within a
period not to exceed five (5) days. In the event that the Owner
informs the Department of extenuating circumstances as to  why
the correction has not been made, a time extension  may be
granted by the Department but in no case will exceed an addi-
tional thirty (30) days.
                                                                                                          CHAPTER SEVEN

    5.  If the Department determines at any time that a serious
threat to the public health exists, the water service will be termi-
nated immediately.
    6.  The Department shall have on file, a list of Private
Contractors who are certified backflow device testers. All charges
for these tests will be paid by the Owner of the building or
    7.  The Department will begin initial premise inspections to
determine the nature of existing or potential hazards, following the
approval of this program  by the Commission, during the calendar
year (       ). Initial focus will be on high hazard industries and
commercial premises.
B.  Owner
    1.  The Owner shall be responsible for the elimination or
protection of all cross-connections on his premises.
    2.  The Owner, after having been informed by a letter from
the Department, shall at  his expense, install, maintain, and test, or
have tested, any and all backflow preventers on his premises.
    3.  The Owner shall correct any malfunction of the backflow
preventer which is revealed by periodic testing.
    4.  The Owner shall inform the Department of any proposed
or modified cross-connections and also any existing cross-
connections of which the  Owner is aware but has  not been found
by the Department.
    5.  The Owner shall not install a bypass around any backflow
preventer unless there is a backflow preventer of the same type on
the bypass. Owners who cannot shut down operation for testing of
the device(s) must supply additional devices  necessary to allow
testing to take place. (Ref. Fig. 33 page 23.)
    6.  The Owner shall install backflow preventers in a manner
approved by the Department. (Ref. Figures 3 through 37, pages 23
through 24.)
    7.  The Owner shall install only backflow preventers ap-
proved by the Department or the Commission.
    8.  Any Owner having a private well or other private water
source, must have a permit if the well or source is cross-connected
to the Department's system. Permission to cross-connect may be
denied by the Department. The Owner may be required to install
a backflow preventer at the service entrance if a private water
source is maintained, even if it is not cross-connected to the
Department's system.
    9-  In the event the Owner installs  plumbing to provide
potable  water for domestic purposes which is on the Department's
side of the backflow preventer, such plumbing must have its own
backflow preventer installed.
    10. The Owner shall be responsible for the payment of all fees
for permits, annual or semi-annual device testing, retesting in the
case that the device fails to operate correctly, and second re-
inspections for non-compliance with Department or Commission
VII. Degree of Hazard
    The Department recognizes the threat to the public water
system arising from cross-connections. All threats will be classified
by degree of hazard and will require the installation of approved
reduced pressure principle backflow prevention devices or double
check valves.
VIII. Permits
    The Department shall not permit a cross-connection within
the public water supply system unless it is considered necessary and
that it cannot be eliminated.
    A.  Cross-connection permits that are required for each
backflow prevention device are obtained from the Department. A
fee of (        ) dollars will be charged for the initial permit and
(       ) dollars for the renewal of each permit.
    B.  Permits shall be renewed every (        ) years and are
non-transferable. Permits are subject to revocation and become
immediately revoked if the Owner should so change the type of
cross-connection or degree of hazard associated with the service.
    C.  A permit is not required when fixture isolation is achieved
with the utilization of a non-testable backflow preventer.
IX. Existing in-use backflow prevention devices.
    Any existing backflow preventer shall be allowed by the
Department to continue in service unless the degree of hazard is
such as to supercede the effectiveness of the present backflow
preventer, or result in an unreasonable risk to  the public health.
Where the degree of hazard has increased, as in the case of a
residential installation converting to a business establishment, any
existing backflow preventer must be upgraded to a reduced
pressure principle device, or  a reduced pressure principle device
must be installed in the event that no backflow device was present.
X.  Periodic Testing
    A.  Reduced pressure principle backflow devices shall be
tested and inspected at least semi-annually.
    B.  Periodic testing shall be performed by the Department's
certified tester or his delegated representative. This testing will be
done at the owner's expense.
    C.  The  testing shall be conducted during the Department's
regular business hours.  Exceptions to this, when at the request of
the owner, may require additional charges to cover the increased
costs to the Department.
    D.  Any backflow preventer which fails  during a periodic
test will be repaired or replaced. When repairs are necessary,
upon completion of the repair the device will be re-tested at
owners expense to insure correct operation. High hazard situa-
tions will not be allowed to continue unprotected if the backflow
preventer fails the test  and cannot be repaired immediately.  In
other situations, a compliance date of not more than thirty (30)
days after the test date will  be established. The owner is respon-

sible for spare parts, repair tools, or a replacement device. Parallel
installation of two (2) devices is an effective means of the owner
insuring that uninterrupted water service during testing or repair
of devices and is strongly recommended when the owner desires
such continuity. (Ref. Fig. 33 page 23.)
    E.  Backflow prevention devices will be tested more fre-
quently than specified in A. above, in cases where there is a history
of test failures  and the Department feels that due to the degree of
hazard involved, additional testing is warranted. Cost of the
additional tests will be born by the owner.

XI. Records and Reports

A.  Records
    The Department will initiate and maintain the following:
    1.  Master files on customer cross-connection tests and/or
    2.  Master files on cross-connection permits.
    3.  Copies of permits and permit applications.
    4.  Copies of lists and summaries supplied to  the
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
    3.  Annual update lists of items 1 and 2 above.
    4.  Annual summary of cross-connection inspections to the

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.

1.  Residential dual check
    Effective the date of the acceptance of this Cross-Connection
Control Program for the Town of (        ) all new residential
buildings will be required to install a residential dual check device
immediately downstream of the water meter. (Ref. Figure 37
page 24.) Installation of this residential dual check device on a
retrofit basis on existing service lines will be instituted at a time
and at a potential cost to the homeowner as deemed necessary by
the Department.
    The owner must be aware that installation of a residential dual
check valve results in a potential closed plumbing system within
his residence. As such, provisions may have to be made by the
owner to provide for thermal expansion within his closed loop
system,  i.e.,  the installation of thermal expansion devices and/or
pressure relief valves.

2.  Strainers
    The Department strongly recommends that all new retrofit
installations  of reduced pressure principle devices and double check
valve backflow preventers include the installation of strainers
located immediately upstream of the backflow device. The installa-
tion of strainers will preclude the fouling of backflow devices due to
both foreseen and unforeseen circumstances occurring to the water
supply system such  as water main repairs, water main breaks, fires,
periodic cleaning  and flushing of mains, etc. These occurrences
may "stir up" debris within the water main that will cause fouling
of backflow devices  installed without the benefit of strainers.
                                                                                                          CHAPTER SEVEN  •  37

Appendk A
                           Appendk B
Partial  List of
Plumbing  Hazards
                           Illustrations of
Fixtures with Direct

Air conditioning, air washer
Air conditioning, chilled water
Air conditioning, condenser
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
Coffee urn
Cooling system
Fire standpipe or sprinkler
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

Baptismal fount
Bedpan washer, flushing rim
Brine tank
Cooling tower
Drinking fountain
Floor drain, flushing rim
Garbage can washer
Ice maker
Laboratory sink, serrated nozzle
Laundry machine
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.
Case I (Fig. 44)
A. Contact Point: A rubber
hose is submerged in a bedpan
wash sink.
B. Causes of Reversed Flow:
(I) A sterilizer connected to the
water supply is allowed to cool
without opening the air vent.
As it cools, the pressure within
the sealed sterilizer drops below
atmospheric producing a
vacuum which draws the
polluted water into the sterilizer
contaminating its contents. (2)
The flushing of several flush
valve toilets on a lower floor
which are connected to an
Backsiphonage (Case 1).
undersized water service line
reduces the pressure at the
water closets to atmospheric
producing a reversal of the flow.
C. Suggested Correction: The
water connection at the bedpan
wash sink and  the sterilizer
should be provided with
properly installed backflow
Case 2 (Fig. 45)
A. Contact Point: A rubber
hose is submerged in a labora-
tory sink.
B. Cause of Reversed Flow:
Two opposite multi-story
buildings are connected to the
same water main, which often
lacks adequate pressure. The
building on the right has
installed a booster pump.
                           FIGURE 45.
                           Backsiphonage (Case 2).

A "U



When the pressure is inad-
equate in the main, the build-
ing booster pump starts
pumping, producing a negative
pressure in the main and
causing a reversal of flow in the
opposite building.
C. Suggested Correction: The
laboratory sink water outlet
should be provided with a
vacuum breaker. The water
service line to the booster pump
should be equipped with a
device to cut off the pump
when pressure approaches a
negative head or vacuum.
Case 3 (Fig. 46)
A. Contact Point: A chemical
tank has a submerged inlet.
B. Cause of Reversed Flow:
The plant fire pump draws
suction directly from the city
water supply line which is
insufficient to serve normal
plant requirements and a major
fire at the same time. During a
fire emergency, reversed flow
may occur within the plant.
C. Suggested Correction: The
water service to the chemical
tank should be provided
through an air gap.
Backsiphonage (Case 3).
Case 4 (Fig. 47)

A. Contact Point: The water
supply to the dishwasher is not
protected by a vacuum breaker.
Also, the dishwasher has a solid
waste connection to the sewer.
B. Cause of Reversed Flow:
The undersized main serving
the building is subject to
reduced pressures, and therefore
only  the first two floors of the
building are supplied directly
with city pressure. The upper
floors are served from a booster
pump drawing suction directly
from the water service line.
During periods of low city
pressure, the booster pump
suction creates negative
pressures in the low system,
thereby reversing the flow.
C. Suggested Correction: The
dishwasher hot and cold water
should be supplied through an
air gap and the waste from the
dishwasher should discharge
through an indirect waste. The
booster pump should be
equipped with a low-pressure
cutoff device.
Backsiphonage (Case 4).
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.
Backsiphonage (Case 5).
 Backsiphonage (Case 6).
B. Cause of Reversed Flow:
Gasoline may enter the
distribution system by gravity
or by siphonage in the event of
a leak or break in the water
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.
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
C. Suggested Correction: The
hot and cold water inlets to the
bathtub should be above the
rim of the tub.
                                                                                                         APPENDIX B  • 39

Appendk C
Illustrations  of
    The following presents
illustrations of typical plumbing
installations where backflow
resulting from backpressure is
Case I (Fig. 50)

A. Contact Point: A direct
connection from the city supply
to the boiler exists as a safety
measure and for filling the
system. The boiler water system
is chemically treated for scale
prevention and corrosion
B. Cause of Reversed Flow:
The boiler water recirculation
pump discharge pressure or
backpressure from the boiler
exceeds the city water pressure
and the chemically treated
water is pumped into the
domestic system through an
open or leaky valve.
C. Suggested Correction: As
minimum protection two check
valves in series should be
provided in the makeup
waterline to the boiler system.
An air gap separation or
reduced  pressure principle
backflow preventer is better.
Backflow (Case 1).
Backflow (Case 2)
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
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
Case 3 (Fig. 52)

A. Contact Point: A valve
connection exists between the
potable and the non potable
systems aboard the ship.
B. Cause of Reversed Flow:
While the ship is connected to
the city water supply system
for the purpose of taking on
water for the potable system,
the valve between the potable
and nonpotable systems is
opened,  permitting contami-
nated water to be pumped into
the municipal supply.

Backflow (Case 3).
                              C. Suggested Correction:
                              Each pier water outlet should
                              be protected against backflow.
                              The main water service to the
                              pier should also be protected
                              against backflow by an air gap
                              or reduced pressure principle
                              backflow preventer.
Case 4 (Fig. 53)
A. Contact Point: A single-
valved connection exists
between the public, potable
water supply and the fire-
sprinkler system of a mill.
B. Cause of Reversed Flow:
The sprinkler system is nor-
mally supplied from a nearby
lake through a high-pressure
pump. About the lake are large
numbers of overflowing septic
tanks. When the valve is left
open, contaminated lake water
can be pumped to the public
C. Suggested Correction: The
potable water supply to  the fire
system should be through an air
gap or a reduced pressure
principle backflow preventer
should be used.
Backflow (Case 4).

Appendk D
Appendk E
Illustrations of
Air Gaps
   The following illustrations describe methods of providing an
air gap discharge to a waste line which may be occasionally or
continuously subject to backpressure.
Air gap to sewer subject to
backpressure—force main.
Air gap to sewer subject to
backpressure—gravity drain.
            Indirect waste
                          Ball check

                          Support vanes
       Horizontal waste
Fire system makeup tank for a
dual water system.
Illustrations of
Vacuum  Breakers
Vacuum breakers.
   Brass inset
                                                     Rubber sleeve
                                                     Flush connection

                                                      Cowl nut
                                                                                    Vaccum closes gate
                       Air enters here
                      preventing rise of
                    contaminated liquids
                          in fixtures
                                                                      Air vent
Vacuum breaker arrangement for
an outside hose hydrant.
                                                      vacuum breaker
                                                         1/2nor3/4"EII. m. M.l.galv.
                                                                           Section "A" "A"
                          To fire system
                                                   (By permission of Mr. Gustave J. Angele
                                                   Sr., RE. formerly Plant Sanitary
                                                   Engineer, Union Carbide Nuclear
                                                   Division, Oak Ridge, Tenn.)
                                    Hand wheel
                                                                                       I.RS. hose adapter
                                                                                      Coupling M.l.galv.
                                                                                       APPENDIX E •  41

Appendk F
Air gap The unobstructed
    vertical distance through
    the free atmosphere
    between the lowest
    opening from any pipe or
    faucet supplying water to a
    tank, plumbing fixture, or
    other device and the flood-
    level rim of the receptacle.
Backflow The flow of water or
    other liquids, mixtures, or
    substances into the
    distributing pipes  of a
    potable supply of water
    from any source or sources
    other than its intended
    source. Backsiphonage is
    one type of backflow.
Backflow Connection Any
    arrangement whereby
    backflow can occur.
Backflow Preventer A device
    or means to prevent
    backflow. Backflow
    Preventer, Reduced
    Pressure Principle  Type
    An assembly of differential
    valves and check valves
    including an automatically
    opened spillage port to the
Backsiphonage Backflow
    resulting from negative
    pressures in the distribut-
    ing pipes of a potable water
Cross-Connection Any actual
    or potential connection
    between the public water
    supply and a source of
    contamination or pollution.
Effective Opening The
    minimum cross-sectional
    area at the point of water
    supply discharge, measured
    or expressed in terms of
    (1) diameter of a circle, or
    (2) if the opening is not
    circular, the diameter of a
    circle or equivalent cross-
    sectional area.
Flood-Level Rim The edge of
    the receptacle from which
    water overflows.
Flushometer Valve A device
    which discharges a prede-
    termined quantity of water
    to fixtures for flushing
    purposes and is actuated by
    direct water pressure.
Free Water Surface A water
    surface that is at atmo-
    spheric pressure.
Frostproof Closet A hopper
    with no water in the bowl
    and with the trap and
    water supply control valve
    located below frost line.
Indirect Waste Pipe A drain
    pipe used to convey liquid
    wastes that does not
    connect directly with the
    drainage system, but which
    discharges into the
    drainage system through
    an air break into a vented
    trap or a properly vented
    and trapped fixture,
    receptacle, or interceptor.
Plumbing The practice,
    materials, and fixtures
    used in the installation,
    maintenance, extension,
    and alteration of all piping,
    fixtures, appliances and
    appurtenances in connec-
    tion with any of the
    following: sanitary
    drainage or storm drainage
    facilities, the  venting
    system and the public or
    private water-supply
    systems, within or
    adjacent to any building,
    structure, or conveyance;
    also the practice and
    materials used in the
    installation, maintenance,
    extension, or  alteration of
    storm water,  liquid waste,
    or sewerage, and water-
    supply systems  of any
    premises to their connec-
    tion with any point of
    public disposal or other
    acceptable terminal.
Potable Water Water free
    from impurities present
    in amounts sufficient to
    cause disease  or harmful
    physiological  effects.
    Its bacteriological and
    chemical quality shall
    conform to the require-
    ments of the  USEPA
    National Primary Drink-
    ing Water Regulations and
    the regulations of the
    public health authority
    having jurisdiction.
Vacuum Any absolute pressure
    less than that exerted by
    the atmosphere.
Vacuum Breaker A device
    that permits air into a
    water supply distribution
    line to prevent
Water Oudet A discharge
    opening through which
    water is supplied to a
    fixture, into the atmo-
    sphere (except into an open
    tank which is part of the
    water supply system), to a
    boiler or heating system, to
    any devices or equipment
    requiring water to operate
    but which are not part of
    the plumbing system.
Water Supply System The
    water service pipe, the
    water-distributing pipes,
    and the necessary connect-
    ing pipes, fittings, control
    valves, and all appurte-
    nances in or adjacent to
    the building or premises.
    The water  supply system
    is part of the plumbing

Appendk G
Accepted Procedure and Practice in
   Cross-Connection Control
   Manual, American Water
   Works Association, Pacific
   Northwest Section, 4th Edition.
   Nov. 1985.
American Backflow Prevention
   Association, RO. Box 1563
   Akron, Ohio 44309-1563.
Angele, Gustave Cross-Connection
   and Backflow Prevention,
   American Water Works
   Association. Supplementary
   Reading library Series - No.
   S106, New York 10016.
A Revision of The Notional 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, B.C.
AWWA Standard For Backflow
   Prevention Devices - Reduced
   Pressure Principle and Double
   Check  Valve Types (C509-78),
   American Water Works
   Association, Denver, Colorado,
   Reaffirmed 1983. Backflow
   Prevention and Cross-Connec-
   tion Control, AWWA Manual
   Ml4, American Water Works
   Association, Denver, Colorado
Backflow Prevention and Cross-
   Connection  Control, Ohio EPA,
   Office of Public. Water Supply.
   Second Edition, Revised Mar.
   15, 1977. Backflow Prevention
   Devices—Selection, Installation,
   Maintenance, and Field Testing,
   CSA Standard B64.10M1981.
   Canadian Standards Association,
Backflow—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.l, I960.
Cross-Connection  Complications,
   The Capital's Health, Vol. 11,
   No. 9,  Dec. 1953, B.C. Dept. of
   Public  Health, Washington,
Cross-Connection Control, American
   Water Works Association,
   British Columbia Section,
   Second Edition, Jan. 1980. Cross-
   Connection Control and Backflow
   Prevention Device Testing, New
   England Water Works Associa-
   tion, August 1987.
Cross-Connection Control and Backflow
   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, Division of Environ-
   mental Quality, Department  of
   Natural Resources, State of
Cross-Connection Control Manual,
   Division of Sanitary Engineer-
   ing, Tennessee  Dept. of Public
   Health, 1975.
Cross-Connection Control Regula-
   tion in  Washington State,
   Washington State Dept. of
   Social and Health Services,
   Denver, Colorado, 1974. Second
Cross-Connection Control, New
   York State Dept. of Health,
   Jan. 1981.
Cross-Connection Control Program,
   State of Utah, Oct.1985, Travis
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 Backflow Preventers, B64
   Series 1976 Canadian Standards
   Association,  Dec. 1976.
Dawson, F. M.,  and Kalinske, A.
   A., Report on Cross-Connect ions
   and Backsiphonage Research,
   Technical Bulletin No. 1,
   National Association of
   Plumbing, Heating, Cooling
   Contractors, Washington, D.C.
Evaluation of Backflow Prevention
   Devices—A State of the Art, (N B
   SIR 76-1070) U.S. Environmen-
   tal 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 of the
   Province of Manitoba.
Manual of Cross-Connection
   Control, Dept. of Health and
   Hospitals, Denver, Colorado,
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 Proce-
   dures, 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, Definitions and Specifications of
   Double Check Valve Assemblies and
   Reduced Pressure Principle Backflow
   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. 1, Sept.
   1970; Pt. 2, Oct. 1970.
                                                                                                                        APPENDIX G  •  43

Appendk H
Survey Form
Name of Company, Corporation, or Business:

Name of Contact:
Type of Use: Industrial Commercial Governmental
Location of Service:
Size of Service: Inch Metered?
Require non-interrupted water service?
Does Boiler Feed utilize chemical additives?
Is Backflow protection incorporated?
Are air conditioning cooling towers utilized?
Is Backflow protection incorporated?
Is a Water Saver utilized on condensing lines or cooling towers? N/A D
Is the make-up supply line backflow protected?
Is process water in use, and if so, is it potable supply water or "Raw" water
Is fire protection water separate from the potable supply?
Are Containment Devices in place?
Degree of Hazard:
Type of Device recommended for containment: RPZ d
Fixture Outlet protection required?
If so, where?


Yes D No D
Yes D No D
Yes D No D
Yes D No D
Yes D No D
Yes D No D
Yes D No D
Yes D No D
N/A D Potable D
Protected D Unprotected D
Yes D No D
Yes D No D

High D Low D
DCV D None D
Yes D No D


Appendk I
Backflow Prevention Device
Test and  Maintenance Report
     (water purveyor or regulatory agency)
Attn: Cross-connection Control Section
The cross-connection control device detailed hereon has been tested and maintained as required by the
(rules or regulations) of (purveyor or regulatory agency) and is certified to comply with these (rules or
  Make of device
  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 D
RP - psid
Leaked 1 — 1

DC-Closed Tight
RP- psid

2nd Check
Closed Tight 1 	 1
Leaked 1 	 1

Closed Tight LH
Relief Valve
Opened at

Opened at

Pressure Vacuum Breaker
Air Inlet
Opened at
Did not open 1 	 1

Opened at

Check Valve
Leaked 1 	 1


The above is certified to be true.
Firm Name
Firm Address
Certified Tester
Cert. Tester No.