ABSTRACT

                EVALUATING BACKFLOW PREVENTION AS A POTENTIAL
                                WATER SECURITY STRATEGY
Backflow is the undesirable reversal of flow of non-potable water or other substances into the piping of
a public or private water supply. This phenomenon can occur as a result of pressure changes associated
with improper cross connections, and has been a significant cause of outbreaks of waterborne disease in
the U.S., as well as being responsible for chemical contamination of drinking water. Backflow prevention
has been used to protect distribution systems from accidental contamination originating from chemical
plants, sewage treatment plants, farms, public swimming pools, and other high  risk facilities.  Design
configurations vary from simple air gap devices to more
sophisticated reduced pressure backflow assemblies. The
U.S. Environmental Protection Agency's Water Security
Research and Technical Support Action Plan recognizes
backflow prevention as a potential strategy for protecting
the public against intentional acts, as well.
                                                           Municipal water supply backflow preventer
This paper presents an evaluation of this strategy with
regard to current and emerging product designs, technical
feasibility for widespread use at residential connections,
protection of fire hydrants, associated cost implications, and existing guidance and regulations as they relate
to cross connection control programs. This paper also examines vulnerabilities associated with blow-offs
and water-related construction activities. Further, the paper discusses the benefits of properly installed,
maintained, and secured backflow preventers, as well  as administrative and technological approaches
for protecting distribution system vulnerabilities. The  study concludes with a set of recommendations
for further work that range from continued development and training on tools for evaluating distribution
system vulnerabilities to utility consideration of phased-in residential water meter replacement programs
using integral backflow preventers.
When completed, the document will be available on the websites of the Water Information Sharing and
Analysis Center at http://waterisac.org and the Water Security Channel  at http://watersc.org.  The sites are
available to all drinking water and wastewater utilities.

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