Advice on legislation or legal policy issues contained in this paper is provided for use in parliamentary debate and for related parliamentary purposes. This paper is not professional legal opinion.
Briefing Paper No. 16/1998 by Stewart Smith
Page Content
There are four main characteristics of drinking water used to describe its
quality. These are: physical; microbiological; chemical; and radiological (page
1). Each of these four areas are very important in their own right. However, in
Sydney, lately specific attention has been paid to the microbiological
characteristics of drinking water (pages 8-15).
The protozoan parasites Cryptosporidium and Giardia have recently been detected
in the distribution system of Sydney Water, leading to boil water alerts in the
community (pages 17-24). The ingestion of the cysts of these organisms, which
is the environmentally resistant stage of the pathogen, can result in diarrhoea
and stomach cramps in affected persons. There is no treatment available for
disease caught from Cryptosporidium, the body naturally repels the parasites
after a period of time. However, in the immuno-suppressed, the body is less
able to do this and death may result (pages 9-14).
Current drinking water guidelines in Australia provide little assistance for
water supply authorities in relation to the presence of Cryptosporidium or
Giardia in drinking water. Developments overseas, notably the United Kingdom
and the United States, have provided some guidelines on international best
practice for the presence of these pathogenic organisms in drinking water
(pages 27-33).
Outbreaks of disease resulting from Cryptosporidium and Giardia contaminated
drinking water have occurred around the world. In Milwaukee in the United
States, a contamination event in 1993 resulted in over 400,000 people sick and
104 people died. In Sydney, while these organisms have recently been detected
in the water distribution system, no increase in disease has been identified.
Modern water treatment plants like Prospect Treatment Plant should be able to
remove 99% of Cryptosporidium oocysts. However, the Sydney Water Inquiry has
concluded that this does not appear to be the case, and further disinfection
technologies may need to be investigated for the Sydney water supply (pages
19-24). The source of the pathogenic organisms in the Sydney water supply is
yet to be finally determined. Overseas, with similar outbreaks it has proved
impossible to pinpoint the source of water contamination. In Sydney,
considerable work can be done to improve the catchment management of Warragamba
Dam, helping to eliminate some potential sources of contamination for the
city's water supply (page 33).