Sydney (New South Wales) – Cryptosporidium, Giardia
“The most publicised incident of drinking-water contamination in Australia occurred from July to September 1998 in Sydney. High numbers of Cryptosporidium (see Fact Sheet) and Giardia were reported for treated water, and boilwater notices were issued for three million residents. No increase in illness was detected in association with the contamination despite increased epidemiological surveillance. An epidemiological study in Queensland showed no correlation between infection and source of drinking water, point-of-use treatment (boiling or filtration) or recreational contact with water (Boreham and Phillips 1986). Another study identified contact with septic tank waste or contaminated soil as a possible mechanism of infection (Boreham et al 1981). An outbreak of illness associated with drinking water was reported in Victoria when mixed infections due to Cryptosporidium and Giardia followed contamination of a private water supply by overflow from a septic tank (Lester 1992)”. (Fact Sheet Giardia ADWG 2011).