What is Chlorodifluoromethane* and Why Does It Matter?

Chlorodifluoromethane (also called HCFC-22 or R-22) is a refrigerant chemical that has been widely used in air conditioning systems and refrigerators for decades. It enters drinking water supplies primarily through industrial discharge, improper refrigerant disposal, and leaks from cooling equipment near water sources. When HCFC-22 breaks down in the environment, it can seep into groundwater or surface water that feeds municipal treatment systems. It's worth noting the asterisk on this contaminant's name — detection in water systems is still being studied, and monitoring data continues to evolve.

Right now, no water systems among the 156 that detected chlorodifluoromethane are testing above any established health guideline. The average detected level is 0.081 parts per billion (ppb), and the highest recorded level is 0.705 ppb. At these concentrations, the immediate health risk appears low. That said, HCFC-22 is classified as a possible concern at higher exposures, with some animal studies linking prolonged exposure to liver and kidney stress. The EPA and research bodies like the Environmental Working Group (EWG) continue to monitor whether long-term, low-level exposure carries cumulative risks — especially for children and pregnant women, whose bodies are more sensitive to chemical buildup.

The EPA has not yet set a Maximum Contaminant Level (MCL) specifically for chlorodifluoromethane in drinking water. That regulatory gap means water utilities aren't legally required to reduce it, even if levels rise. The EWG has flagged this as a chemical worth watching, particularly as HCFC-22 use has been phased down under the Clean Air Act — but older equipment still leaches it into the environment. Without a firm federal limit, the burden falls on individual households to stay informed and take steps to filter their own water if they're concerned.

Geographically, Colorado leads all states with 37 water systems detecting this contaminant, followed by Florida (16), Illinois (15), California (12), and Kansas (11). Colorado's numbers likely reflect the state's heavy use of refrigeration and HVAC systems in both its mountain resort communities and urban centers like Denver. Florida's warm climate drives year-round air conditioning use, which increases the chance of refrigerant leaks near water infrastructure. Illinois and Kansas both have significant agricultural and industrial sectors where refrigeration equipment is common. California's detections are spread across a large and densely populated state with aging industrial infrastructure in many regions. The pattern points to a clear link between refrigerant-heavy industries and climates that demand constant cooling.

The good news is that chlorodifluoromethane can be effectively reduced with the right filtration. Activated carbon filters can capture many volatile organic compounds and refrigerant byproducts, and a reverse osmosis (RO) system offers even stronger protection — removing up to 99% of a wide range of dissolved contaminants. Echo Water's reverse osmosis systems are designed to handle exactly this kind of low-level chemical contamination, giving your household a consistent layer of protection even when regulatory standards haven't caught up to the science. If you live in Colorado, Florida, Illinois, California, or Kansas, it's worth checking your local water quality report (available through your utility's annual Consumer Confidence Report) to see whether this contaminant has been detected in your specific system. Knowing what's in your water is the first step — filtering it out is the second.

Regulatory Standards for Chlorodifluoromethane*

Cities With the Highest Chlorodifluoromethane* Levels

States Most Affected by Chlorodifluoromethane*

Frequently Asked Questions

Related Contaminant Guides