10133712_lUSA: State officials in New York are to investigate how chlorodifluoromethane, better known as the refrigerant R22, has contaminated a drinking water well on Long Island.

The New York State Department of Environmental Conservation will try to determine how the toxic refrigerant got into a well on Diana’s Trail in Roslyn Estates, a village on the north shore of Long Island.

The well was shut down in November when the chlorodifluoromethane contamination was measured at 4.3µg/l (0.0043ppm). The maximum considered safe contaminant level is 5µg/l (0.005ppm). The Roslyn Water District also partially shut down two other wells due to varying levels of chlorodifluoromethane  contamination.

Traces of dichlorodifluoromethane contamination, better known to us as the CFC R12, were also found in the same well but at much lower levels.

While the source of the contamination remains a mystery, an air conditioning or refrigeration installation is suspected.

While reports of this sort are extremely rare, this is not the first occurrence of this type of contamination in the US. In New York State there have previously been three reports of chlorodifluoromethane in tap water since 2004.

The worst case was in Manhasset when an average of 0.00183ppm was recorded but this had peaked at 0.015ppm. First detected in 2002, the contamination eventually resulted in a $2.75m settlement with a local hospital in 2009, after it was suspected that the contamination occurred due to leaks in the hospital’s air conditioning system. The R22 crossed over into fresh water being pumped through the systems as part of the normal cooling process. This water was then discharged directly into the aquifer system through recharge wells.

Last year, traces of R22 were also found in four private wells in Sequim, a city in Clallam County, Washington.