Environmental Engineering Reference
In-Depth Information
waterborne diseases have not been eliminated and other diseases, previously
considered not typically transmissible or thought to be transmissible by the water
route, are being discovered.
In the general sense, Lashley
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outlines preventive measures to be taken to
control waterborne disease, including the safeguard of drinking water, recreational
water, and more stringent actions for the protection of immunocompromised per-
sons. Immunocompromised individuals should not rely on tap waters without
additional home treatment such as boiling for one minute or treatment with cer-
tain filters. The CDC AIDS Hotline (1-800-342-2437) is available for additional
information on this subject. Immunocompromised persons should be especially
careful about exposure to fecal matter, young animals — which are more apt to be
carriers of infectious disease organisms that are especially difficult (e.g.,
Cryp-
tosporidium
and
Cyclospora
agents) — and travel to countries with low-grade
sanitation.
Prevention of Waterborne Diseases
A primary requisite for the prevention of waterborne disease at the community
level is the ready availability of an adequate supply of water that is of satisfactory
sanitary quality for meeting microbiological, chemical, physical, and radiological
standards. The prevailing scheme in the water treatment industry for the establish-
ment of a reliable water purification system is the multiple-barrier concept.
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The
multiple-barrier plan for the treatment of water is, in effect, a fail-safe program
for ensuring the safety of the consumer of finished water, should a step in the
overall process fail. The barriers thus proposed are (1) source water protection,
(2) water treatment plant processes, (3) disinfection practices, (4) distribution sys-
tems, (5) security, and (6) education. Protection of source water deals with the
selection and developing of the raw water supply and safeguarding the watershed
from infiltration of pollution. Water treatment plant processes entails the appro-
priate and proper unit operations and the necessary measures to maintain plant
functions. Disinfection practices assume the maintenance of an adequate disin-
fectant residual throughout the distribution system for destruction of pathogenic
agents arising from the untreated source water and faults within the distribution
system. The distribution system includes inspection and remediation of piping
and inline storage facilities. Security involves the physical watch on the treat-
ment system against the possibility of unlawful entry, with the intent to disrupt or
compromise treatment operations and goal of producing quality water. Education
embraces the training of water treatment personnel and informing public officials
and the public at large of any emergency measures required, owing to interrup-
tions in operations that may affect water quality and quantity. Publicly owned
water companies are preferred because they usually provide water of satisfactory
quality and quantity and are under competent supervision. It is important that
the finished water be convenient, attractive, and palatable to inspire public con-
fidence in the product and dissuade alternate choices of expensive bottled waters
or the selection of some other source water, such as a nearby well or spring of
