Sydney Water denies it was involved in a cover-up after water supplies in south Sydney were contaminated last year.
A health warning was issued to residents in parts of southern Sydney in December last year after reports the water had a chemical or petrol taste.
Sydney Water said the contamination occurred when compounds from bitumen were let into a water pipe during routine maintenance.
But AAP reports the incident has sparked claims the contamination could be linked to a former ChlorAlkali Plant at Botany, with suggestions Sydney Water may have covered-up the incident and botched test results.
In a statement on Sunday, Sydney Water denied those claims, saying there was never any threat to the public.
"There has been no cover up of any results," Sydney Water said. "Apart from some compounds which created changes to taste and odour in the water, results show the water met the Australian Drinking Water Guidelines."
The company said the NSW Department of Health had been given samples and agreed there was no risk to residents.
But Greens MP Cate Faehrmann said residents living around the former ChlorAlkali Plant at Botany were "scared out of their brains" about contamination.
"The community is not trusting companies like Orica and now companies like Sydney Water to undertake their activities safely," she said. "It's really important the community trust is restored."
NSW Premier Barry O'Farrell said he would happily drink from taps in Sydney's south because the health department had ruled there was no evidence the incident was linked to the Orica plant.