What is Dichlorodifluoromethane* and Why Does It Matter?

Dichlorodifluoromethane (also known as Freon-12 or CFC-12) is a synthetic chemical that was once widely used as a refrigerant and aerosol propellant. For decades, it showed up in air conditioners, refrigerators, and spray cans before being phased out under the 1987 Montreal Protocol due to its role in depleting the ozone layer. So how does it end up in drinking water? It can seep into groundwater from old refrigeration equipment, industrial waste disposal sites, and legacy manufacturing facilities. Improper disposal of refrigerants is a common pathway. Once it enters an aquifer, it can persist for years.

Current detection data shows dichlorodifluoromethane appearing in 11 water systems across the United States. The average detected level is 1.525 parts per billion (ppb), with the highest recorded measurement reaching 7.8 ppb. The good news is that none of the 11 systems detected it above established health guidelines. That said, detection at any level is worth understanding, especially for parents and anyone drinking that water daily over many years.

The health effects of dichlorodifluoromethane depend heavily on the level and duration of exposure. At high concentrations — far above what's found in drinking water — it can affect the central nervous system and cause dizziness, irregular heartbeat, and in extreme cases, cardiac arrest (according to occupational health data from the CDC). At the low levels found in tap water, the immediate health risks appear minimal. However, long-term, low-level exposure is less well studied. The EPA classifies CFC-12 as not likely to be carcinogenic to humans based on current data, but researchers continue to study its effects on the liver and kidneys with chronic exposure. When in doubt, reducing any unnecessary chemical exposure in your drinking water is a reasonable step.

From a regulatory standpoint, the EPA has not set a Maximum Contaminant Level (MCL) specifically for dichlorodifluoromethane in drinking water. It falls under broader monitoring programs rather than strict enforceable limits. This is part of why the asterisk appears next to its name in water quality reports — it's detected and tracked, but not formally regulated the same way lead or nitrates are. The Environmental Working Group (EWG) has flagged this gap, noting that many synthetic chemicals detected in tap water lack specific legal limits. The absence of a legal limit doesn't mean the chemical is harmless. It often just means the regulatory process hasn't caught up yet.

Geographically, the data tells an interesting story. New York accounts for 8 of the 11 systems where dichlorodifluoromethane was detected. California accounts for the remaining 3. New York's older industrial infrastructure, aging groundwater sources, and legacy refrigeration facilities likely contribute to this pattern. Many of New York's water systems draw from groundwater that has been influenced by decades of industrial activity. California's detections are concentrated in areas with similar industrial histories. This isn't a nationwide problem yet, but if you're on a water system in either state, it's worth pulling your latest Consumer Confidence Report (CCR) to see if your utility detected it.

The most effective way to remove dichlorodifluoromethane from drinking water is through activated carbon filtration or reverse osmosis. Activated carbon filters work by adsorbing organic compounds — meaning the chemical sticks to the carbon surface and gets pulled out of the water. A high-quality carbon block filter can significantly reduce levels of volatile organic compounds like CFC-12. Reverse osmosis goes a step further, pushing water through a semi-permeable membrane that blocks a wide range of contaminants. Echo Water's reverse osmosis systems are designed to address exactly this kind of synthetic chemical contamination, giving you a reliable layer of protection at the tap. If you're in New York or California and want to know your specific risk, start with your CCR, then consider point-of-use filtration as a straightforward, practical safeguard for your household.

Regulatory Standards for Dichlorodifluoromethane*

Cities With the Highest Dichlorodifluoromethane* Levels

States Most Affected by Dichlorodifluoromethane*

Frequently Asked Questions

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