11/93 (Fifth Reprint w/ 11/95 Update)
Michigan Department of Public Health
Division of Water Supply
3423 North Logan Street/Martin L. King Jr. Blvd.
Post Office Box 30195
Lansing, Michigan 48909
D-214 11/93 Authority: Act 399, P.A.
1976
The department wishes to recognize
the efforts of Mike Kovach, department coordinator for cross connection
policy, and Eric Way, Training Specialist, for developing the
second edition of the rules manual; also, Suzanne Olivier and
Irene Morado for typing and proofing the text. Representatives
from the plumbing industry, especially the late Larry Burkheiser
who contributed vast expertise to the field of cross connection
control, are also acknowledged. The department specifically wishes
to thank the Pacific Northwest Section, American Water Works Association,
Cross Connection Control Committee for permission to use some
of the illustrations from their training text, Accepted
Procedure and Practice in Cross Connection
Control Manual, Second Edition.*
*Illustrations appearing on Pages 10,
17, 21-24, 27, 30-34, and 47 were taken from the Pacific Northwest
Section, AWWA, training manual.
NOTE: Some of the illustrations in the printed
Manual have not yet been included in this on-line version
In recent years, amendments to the
Federal Safe Drinking Water Act have caused much attention to
be focused on such issues as organic contamination and lead in
drinking water. Although these topics deserve the attention of
the water supply industry, other equally important areas of risk
must continue to receive emphasis by utility officials. Cross
connection control remains a critical link to maintenance of drinking
water quality throughout a potable water supply piping network.
Without a continued concerted effort in this area by water utility
personnel, water quality will be jeopardized regardless of any
effort to control the source of supply. This manual remains a
tool to educate the industry about the need for effective cross
connection control.
James K. Cleland, P.E., Chief
Division of Water Supply
Bureau of Environmental and Occupational Health
Michigan Department of Public Health
Section
14.2 WATER SUPPLY CROSS CONNECTION RULES
14.3.2 Reduced Pressure Principle Backflow Preventer
14.3.4 Four-Way Plug Valve and RPPBP in Series
14.3.5.1 Atmospheric Vacuum Breaker
14.3.5.2 Pressure Vacuum Breaker
14.4.1 Cross Connection with a Secondary Water Supply
14.4.2 Cross Connection by Submerged Inlet
14.4.3 Cross Connection with Sanitary Wastes or
14.4.4 Cross Connection by way of Immersed Piping
14.4.5.1.1 Domestic Booster Pumps
14.4.5.2 Chemical Treatment of Customer Piping Systems
14.4.5.3 Common Wall Heat Exchangers
14.4.5.6 Municipal Water Supply Distribution Systems
14.4.5.6.1 Stop and Waste Valves; Hydrant Weep Holes;
14.4.5.6.2 Sewer Flushing Lines
14.4.5.6.3 Fire Hydrant Additives
14.4.5.8 Fire Protection Systems
14.4.5.10 Residential Cross Connections
14.4.5.11 Commercial Car Washes
14.6 LOCAL CROSS CONNECTION CONTROL PROGRAM
14.6.1 Local Ordinance - Enforcement Agency
14.6.2 Schedule of Inspections
14.6.6 Recordkeeping and Annual Report
14.7 CONTAINMENT AND ISOLATION
14.8 ACCEPTABLE MEANS OF PROTECTION
14.8.1 Secondary Water Supplies
14.8.2 Submerged Inlet or Connection into Pipes or Tanks
C. Model Cross Connection Control Program
D. Suggested Recordkeeping Formats
3. Backflow Preventer Test Results Form
E. Test Procedures for Backflow Prevention Devices
G. Fire Systems - AWWA Manual M-14
1. Reduced Pressure Principle Type
2. Double Check Valve Assemblies
4. Atmospheric Vacuum Breakers
Historically, the water works industry has made
a determined effort to provide the consumer with an unlimited
quantity of high quality water. Much of this effort, however,
has been concentrated on the production of a quality treated water
with insufficient attention paid to protecting the quality of
the water within the distribution system. Connections between
piping containing contaminants
or potential contaminants and potable water supply piping are
encountered on all public water supply distribution systems to
some extent. The control of these cross-connections is difficult
since it demands the inspection and necessary reinspection of
industrial and commercial establishments, as well as some control
of private dwellings.
Too often total reliance has been placed on producing
a safe water and attempting to maintain good pressure throughout
the distribution system at all times. While these efforts are
of extreme importance, they have not proved to be entirely effective
in protecting the water quality within the distribution system.
It is essential that all cross connections on the public water
supply distribution system be removed in order to protect the
quality of water within the public system when distribution system
pressure is less than adequate by itself to prevent backflow.
The water supply cross connection rules define cross connection
as, "a connection or arrangement of piping or appurtenances
through which a backflow could occur." In turn, backflow
means, "water of questionable quality, wastes or other contaminants
entering a public water supply system due to a reversal of flow."
By definition then, the tern backflow includes situations caused
by either backpressure or backsiphonage
.
Since passage of the cross connection control rules
in April of 1972, much effort has been spent by many water utilities
in the state to maintain an effective cross connection
control
program. However, cross connections on public water supply distribution
systems continue to pose a distinct threat to the potability of
the water supply. All water utilities must continue to strive
toward eliminating and preventing any cross connections with the
public water supply system. To illustrate the type of conditions
and problems that exist, the following examples of cross connection
problems which have occurred both in Michigan and out of state
are included. They are mentioned here merely to illustrate that
problems do exist.
14.1.1 Case Histories
In 1938, some 80 students at Michigan State University were infected with brucellosis. The problem seemed to be isolated to those individuals working within the laboratory building. It was later determined that a hose connected to the tap was routinely submerged in a sink used for cleaning materials utilized in studies on the brucellosis culture. The sink was located on an upper floor and the water system at that elevation was subject to fluctuations in pressure, including negative pressure on occasions. Persons consuming water in the affected areas would consume contaminated water. Of the 80 students infected, one died.
In 1963, a freighter docked at a Great Lakes port,
caused the contamination of a portion of the public drinking water
supply system. The ship had been utilizing city water for sanitary
purposes throughout the winter months while in the yard for repairs.
Prior to resuming its normal shipping season in the spring, it
was necessary to test the fire fighting system. It was later
determined that approximately 3,000 gallons of untreated surface
water were pumped into the city system over a period of 45 minutes.
The problem was first noticed when an employee in another portion
of the shipyard noticed the water from a drinking fountain was
highly turbid. The city water superintendent was notified and
he immediately increased the chlorine application at the water
treatment plant and began flushing hydrants in the area to remove
the contamination from the system as soon as possible. This demonstrates
how problems of an extremely serious nature can occur without
the public water supply losing pressure. The high pressure fire
pumps were operated at approximately 100 psi while the city was
maintaining normal pressure of about 60 psi in the vicinity.
All persons involved were extremely fortunate that no sickness
or other problems resulted from this severe cross connection problem.
In 1966, the distribution system in a city with
a population of approximately 25,000 was contaminated with chemical
siphoned from industrial plating tanks. This problem was definitely
a case of backsiphonage caused by low pressure in the distribution
system (main break) and submerged inlets into the plating tanks.
The discoloration of the water warned of the problem before any
of the contaminated water was consumed. The example demonstrates
how serious backsiphonage situations can be, particularly in instances
where discoloration does not occur.
One of the most highly publicized cases of a cross
connection incident took place out of state. In 1969, the football
season at Holy Cross University was terminated due to a large
outbreak of infectious hepatitis among the team members. During
the ensuing investigation, it was determined that backflow through
an unprotected lawn sprinkling system and the resulting contamination
of the drinking water supply at the practice football field was
the cause of the epidemic. Children carrying the hepatitis virus
were known to routinely play in the puddles surrounding the sprinkling
heads. Later evaluations indicated that fire fighting demands
in the vicinity could have caused negative pressures at sprinkling
heads in question. Approximately 75 team members and others associated
with the team were affected.
Another rather highly publicized incident ironically
took place at the Boston hotel hosting the 1974 National Conference
of the American Water Works Association. It was discovered that
the hotel drinking water system had become contaminated during
the conference with chromium through a submerged inlet cross connection
with the building's air conditioning system.
In 1979, a direct cross connection with piping serving a car wash in a small rural Michigan community caused contamination of a portion of the municipal water distribution system. The cause of the problem was found to be a direct piping connection between the car wash booster pumping system and the water service line to the car wash building.
Backpressure backflow of ammonia refrigerant took
place in the spring of 1981 in a major Upper Peninsula community
of Michigan. The incident resulted in contamination of a significant
portion of the distribution system.
In May of 1982, malathion was backsiphoned into
the distribution system of a small Michigan village as the result
of system shutdown for repairs. Fortunately, flushing of the system
and public notice of the problem took place before the water was
consumed.
In February of 1984, soap and rinse water was backflowed
into a village water system in Michigan again as the result of
a car wash. Four restaurants and a laundrymat were affected.
A booster pump for reclaiming rinse water was found to be directly
tied into the service line from the city main.
These illustrations of actual problems make it apparent
that additional protection must be afforded our public water supply
systems. It is estimated that 90% of the incidents of backflow
through cross connections either go unreported or are not observed.
Historically, in Michigan, an effort has been made to protect
the public water supplies from backflow by maintaining adequate
pressure on the distribution system. The distribution system
and service lines must be adequately sized to provide for fire
flows without serious loss of
pressure if we are to be successful in protecting against backflow
even with an ongoing cross connection control program. Certainly,
the distribution system must be adequately sized to provide for
peak usage of any service; i.e., fire flow. It
should be apparent that the design of the distribution system,
including factors such as main placement and sizing, valving,
and storage, is of extreme importance in protecting against backflow
conditions.
This manual is meant to serve as a guideline for
water utilities to follow when implementing a local cross connection
control program. There are many situations one may encounter
when making inspections where a clear cut solution is not possible
or when corrective action is not popular. The utility must keep
in mind that when seeking a solution to a particular problem the
public health of its customers is at stake. Individual counseling
with representatives from the Michigan Department of Public Health
is recommended before final decisions are reached on unusual cases.
It may be necessary for department staff engineers to make an
on site inspection in order
to render a fair and effective decision.