Environmental Engineering Reference
In-Depth Information
1. The presence of infecting viruses in drinking water is a potential
hazard to public health, and no valid basis exists upon which a no-
effect concentration of viral contamination in finished drinking
water might be established.
Note:
This statement in no way should be interpreted to mean that
viruses are not removed by conventional treatment and disinfection. On
the contrary, drinking water produced by an effective conventional treat-
ment and distributed after disinfection is expected to have significantly
reduced concentrations of viruses inactivated by the treatment.
2. Continued testing for viral contamination of potable water should be
carried out with the facilities and skills of a wide variety of research
establishments, both inside and outside of government, and method-
ology for virus testing should be improved.
3. The bacteriological monitoring methods currently prescribed or rec-
ommended in this report (coliform count and standard plate count)
are the best indicators available today for routine use in evaluating
the presence in water of intestinal pathogens, including viruses.
In 1987, the USEPA concluded that measuring the level of enteric viruses in
drinking water is not economically or technologically feasible for the follow-
ing reasons: Currently acceptable methods require levels of expertise that
utility personnel normally do not possess, and the methods would be too
expensive if analyzed by private laboratories. Validation procedures have
not yet been established. Continuous monitoring would be required, but
monitoring does not provide advance notice to ensure the safety of drinking
water at the consumer's tap (DeZuane, 1997).
DID YoU KNoW?
Viruses can infect virtually all types of cells: bacteria, protozoa,
plants, fungi, animals, and humans. True parasites, viruses are
basically little more than molecular syringes moving genetic infor-
mation from one cell to another. Some viruses enter a host and leave
virtually unnoticed. Others cause disease and destroy the host.
Protozoa
The
protozoa
(“first animals”) are a large group (more than 50,000 known
species) of eucaryotic organisms that have adapted a form or cell to serve as
the entire body. In fact, all protozoans are single-celled organisms. Typically,