FINDINGS show record levels of dangerous parasites in Sydney's water. And the real culprits are harmless algae, says ferry Ongerth, a consultant in the board dealing with contamination crises. He says the levels of cryptosporidium and giardia found in most recent health department samples are "as high as you would find in pure raw sewage, probably higher".
His own tests, on the other hand, had found "lots of algae of different species, some of which look very like giardia and some of which look very like cryptosporidium."
"Nature is large," says Ongerth, a visiting fellow at the Department of Civil Engineering at the University of New South Wales (NSW). "There are so many organisms out in nature that you cannot possibly test for all of them."
The NSW health department reports that more than 9,000 oocysts of cryptosporidium per 100 litres of treated water have been found. However, Ongerth says the highest figure ever reported in the us water supply was 1,000. This included a contamination in Milwaukee in 1995 which made hundreds of thousands of people ill.
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