Environmental Engineering Reference
In-Depth Information
Cryptosporidium
and thus avert outbreaks. Efforts are underway to answer
questions about the occurrence, detection, and treatment of
Cryptosporidium
in water so that the USEPA and states can set specific standards for this para-
site in the future (Fayer et al., 1997). The collaborative efforts of water utilities,
government agencies, healthcare providers, and individuals are necessary to
prevent outbreaks of cryptosporidiosis.
SIDEBAR: SYDNEY AUSTRALIA*
From the end of July to the end of September 1998, upon three occasions, residents of the city
of Sydney, Australia, had to take the precaution of boiling their drinking water. Testing found
Giardia
and
Cryptosporidium
in the public water supply. According to the Sydney authori-
ties, at these levels the
Giardia
and
Cryptosporidium
cysts posed little, if any, health threat. No
incidents of illness were linked to the presence of
Giardia
and
Cryptosporidium
; however, busi-
nesses that relied on large quantities of pure water could not function on a boil-alert quality
of water. Evidence seemed to indicate that the plant itself was creating the problem and that
the results of water tests performed by the lab (Australian Water Technologies) were either
conducted improperly or were not read properly and misinterpreted.
The aftermath of the incidents left the Sydney Water Corporation, the privately owned
organization handling the treatment systems since privatization in 1995, in shambles.
Beginning on July 29, 1998, the three boil alerts led to a massive investigation into the causes
and sources of the contamination, as well as the resignation of Sydney Water Corporation's
managing director and chairman, whose blossoming political career was cut short. Sydney
Water Corporation was stripped of responsibility and its major assets; it lost all control
of its treatment plants, dams, and catchment to the government's new Sydney Catchment
Authority. Sydney Water Corporation was ordered to repay residential water users for the
expense and trouble of using bottled water, and, of course, numerous lawsuits were initiated
by businesses and industries affected by the shutdown.
On the positive side, Australia has put an American-style Clean Water Act into place
(which, if nothing else, will establish guidelines to follow in such a case), and Sydney is work-
ing to ensure good preventive maintenance measures for watershed protection.
Of special interest to water pollution control technologists are the tests, their results,
and the difficulty in pinpointing the source (or sources) and cause of the contamina-
tion. Experts warned that actually finding the direct source of the Sydney outbreaks was
unlikely (e.g., the cause of the 1995 outbreak in Milwaukee is uncertain), and they recom-
mended installing either an ozonation or microfiltration system to ensure completely safe
drinking water. Such expert advice, though, presumed actual
Giardia
and
Cryptosporidium
contamination—which at that point was in more than a little doubt. Test results on the
same water samples taken during the outbreaks varied widely. Tests for the later shut-
downs were less accurate than ones for the initial shutdown—not surprising under the
panic conditions at the lab, which was under tremendous pressure to find the causes and
was reluctant to risk either consumer wrath over the inconvenience or consumer illness
and death due to contamination.
One test sample was read at 1000
Cryptosporidium
oocysts initially, but a reexamination
of the sample found only 2 oocysts. Technicians may also have mistaken harmless algae
similar in appearance to
Giardia
and
Cryptosporidium
for the dangerous cysts, raising false
(and expensive) alarms. Even in retesting, test results were shaky. The New South Wales
Health Department counted what they thought were more than 9000 oocysts per 100 liters
of treated water for one sample—higher levels than testing should find in raw sewage. An
expert from the department of civil engineering at the University of New South Wales who
saw lots of different algae and no
Cryptosporidium
in his own tests on the water pointed out
* Adapted from Spellman, F.R. and Whiting, N.E.,
Water Pollution Control Technology: Concepts
and Applications
, Government Institutes, Rockville, MD, 1999.
