MELBOURNE Water has labelled as "alarmist" a report that claims one of Melbourne's biggest sources of drinking water has unacceptable levels of pesticides.
Friends of the Earth investigated pesticide levels in the Sugarloaf Reservoir, which supplies drinking water to about 1.5 million Melburnians in the north and west of the city.
The report states that since 2008 there have been 31 positive pesticide samples from the Yarra River, which supplies water to the reservoir in Christmas Hills.
In September 2010, 0.16 micrograms per litre of the pesticide Simazine was detected and, although it was within the Australian Drinking Water Guidelines of 20 micrograms per litre, FoE spokesman Anthony Amis said the levels were still potentially harmful.
The report also states that the filtration process for the reservoir at the Winneke Treatment Plant was not designed to filter out pesticides.
Mr Amis said the results were concerning for people's health and the river's ecological health.
"The Yarra should not be treated like an agricultural drain; it has unique attributes that require urgent protection measures," he said.
Melbourne Water's general manager of asset planning, Paul Pretto, said FoE had misinterpreted the testing data.
"We are very concerned at this alarmist interpretation of our own data," he said. "At no stage have pesticides been detected above the recommended health limits."
Mr Pretto added that water-monitoring results were shared with the Department of Health and the water met the requirements of the Safe Drinking Water Act.
Mr Amis said Australian standards were too lax.
"What actually is alarming is that through our research we've discovered there has been very little pesticide testing for 30 years," he said.
Minister for Water, Peter Walsh, did not respond to a request for comment.