The Importance of Distribution System Disinfection - Disinfection of Pipelines and Storage Facilities Field Guide - page 1

Chapter 1

The Importance of Distribution
System Disinfection

The reports of waterborne disease outbreaks attributed to
drinking water have decreased since high numbers in the 1970s
and 1980s. However, the annual number remains higher than
desirable (Figure 1-1). Acute gastrointestinal illnesses comprise
the majority of these identified disease outbreaks in the United
States. Most of these outbreaks involve microbiological agents
that would respond to proper disinfection.

60

Legionella species*
AGI †
Chemical
Viral
Parasitic
Bacterial

50

40

30

20

10

0

1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001

Year

*Beginning in 2001, Legionnaire's disease was added to the surveillance system, and
Legionella species were classified separately.
† Acute gastrointestinal illness of unknown etiology.

Reprinted from CDC MMWR Surveillance Summaries , October 2004.

Figure 1-1 Number of waterborne-disease outbreaks (n=764) associated
with drinking water, by year and etiologic agent—United States, 1971-2002

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