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Chapter 9

Cross-Connection Control

9.1 INTRODUCTION
Plumbing cross-connections, which are defined as actual or potential connections between
a potable and nonpotable water supply, constitute a serious public health hazard. There are
numerous, well-documented cases where cross-connections have been responsible for con-
tamination of drinking water and have resulted in the spread of disease. The problem is a
dynamic one, because piping systems are continually being installed, altered, or extended.
Control of cross-connections is possible, but only through thorough knowledge and
vigilance. Education is essential, because even those who are experienced in piping instal-
lations 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 dan-
gers of cross-connections and should exercise careful surveillance of their systems. The
American Water Works Association (AWWA) stated the following in a policy on public
water supply matters:
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 preven-
tion and cross-connection control programs to protect public water systems from the
hazards originating on the premises of their customers and from temporary connec-
tions 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 purposes 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 commensurate with the degree of hazard are implemented to ensure
continual protection of the water in the public water distribution system. Customers,
together with other authorities, are responsible for preventing contamination of the
private plumbing system under their control and the associated protection of the
public water system. (Reprinted by permission. Copyright © 2009, American Water
Works Association.)
Public health officials have long been concerned about cross-connections and backflow
connections in plumbing systems and in public drinking water supply distribution systems.
Such cross-connections, which make possible the contamination of potable water, are ever-
present dangers. One example of what can happen is an epidemic that occurred in Chicago
in 1933. Old, defective, and improperly designed plumbing and fixtures permitted the con-
tamination of drinking water. As a result, 1,409 people contracted amebic dysentery, and 98
of them died. This epidemic, and others resulting from contamination introduced into a
water supply through improper plumbing, made clear the responsibility of public health
officials and water purveyors for exercising control over public water distribution systems
and all plumbing systems connected to them. This responsibility includes advising and
instructing plumbing installers in the recognition and elimination of cross-connections.

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