A boil-advisory was placed on a small area in southeast Rochester after water samples showed a presence of bacteria in the local reservoir.
The advisory affected approximately 550 households near the Cobbs Hill reservoir. According to the Rochester Democrat and Chronicle, two samples from the reservoir showed bacteria. One even showed the presence of E. coli.
Monroe Country health officials said that there were no reports of illness from the drinking water.
The advisory will be lifted as soon as the water is free of bacteria for two days in a row.
Rochester Environmental Services Commissioner Paul Holahan told the Rochester Democrat and Chronicle that the source of the contamination could be animal feces or dead animals. City officials plan to send a diver into the water to determine the exact cause.
Meanwhile, residents of the area were supplied with water from an alternate source.
Currently, the reservoir is not covered, though federal regulators have ordered that all drinking-water reservoirs be covered or retrofitted with stronger disinfection equipment by 2009.
The city will decide next year whether or not to spend millions on installing covers.