Trichlorofluoromethane in Drinking Water
Found in 30 water systems • vocs
Updated September 2026 • Data from EWG & EPA
What is Trichlorofluoromethane and Why Does It Matter?
TRICHLOROFLUOROMETHANE: WHAT YOU NEED TO KNOW
What Is Trichlorofluoromethane and Where Does It Come From?
Trichlorofluoromethane, commonly known as CFC-11 or chlorofluorocarbon-11, is a synthetic chemical that was widely used in refrigeration, air conditioning, and foam-blowing applications throughout the 20th century. Before its phase-out under the Montreal Protocol in the 1990s, this chemical was released into the atmosphere where it contributed to ozone layer depletion. Today, trichlorofluoromethane still persists in the environment and occasionally appears in drinking water supplies across North America.
The chemical enters water systems through atmospheric deposition and groundwater contamination. When CFC-11 was used in industrial processes, some escaped into the air. Over decades, it has settled into soil and groundwater, particularly in areas with older industrial activity or landfills. Once in the water cycle, it's stubborn—trichlorofluoromethane breaks down very slowly, meaning contamination from decades past can still show up in your tap water today.
Health Effects and Exposure Risks
The health picture for trichlorofluoromethane is less clear than for some other contaminants because it was phased out before extensive human health studies could be completed. However, animal studies suggest potential concerns. The EPA classifies trichlorofluoromethane as a probable human carcinogen, meaning long-term exposure may increase cancer risk. Research indicates it can damage the liver and kidneys at high doses.
Currently, 30 water systems across the United States have detected trichlorofluoromethane, with an average concentration of 1.707 parts per billion (ppb). The maximum detected level reached 40.7 ppb in one system—a significant spike. Importantly, none of these detections exceeded the EPA's current drinking water standard, which means water utilities aren't required to take action. However, the Environmental Working Group (EWG) recommends a much lower health-based guideline for this chemical, suggesting that even the "safe" levels set by regulators may warrant caution for vulnerable populations like children and pregnant women.
The Regulatory Gap
Here's where things get complicated. The EPA has set a Maximum Contaminant Level (MCL) of 150 ppb for trichlorofluoromethane—a threshold based on cancer risk calculations from the 1980s. No water systems in this dataset exceed that limit. However, the EWG's health guideline is significantly stricter, reflecting newer toxicology research and a more protective stance toward vulnerable groups. This gap between EPA and EWG standards is common and highlights why homeowners concerned about water quality shouldn't rely solely on "EPA approved" water as the final word on safety.
Geographic Hotspots and Why They Matter
Trichlorofluoromethane shows a clear regional pattern. New York leads with 9 detections, followed by Wisconsin with 8, and California with 5. Georgia and Washington each have 2. This distribution reflects historical industrial activity and the persistence of old CFC contamination in groundwater-dependent regions. New York and Wisconsin's prevalence likely stems from decades of refrigeration and manufacturing industries. California's detections align with areas relying on groundwater in agricultural and industrial zones. These aren't random—they tell a story of where CFCs were used most heavily before the ban.
Removing Trichlorofluoromethane From Your Water
The good news: trichlorofluoromethane is effectively removed by several filtration methods. Activated carbon filters work well for this contaminant, particularly whole-house systems that treat all water entering your home. Reverse osmosis systems remove up to 99% of CFCs and other volatile organic compounds. If you live in New York, Wisconsin, or California, or if your water utility has notified you of trichlorofluoromethane detection, consider having your water tested. An Echo Water quality test will tell you exactly what's in your tap water and which filtration approach makes sense for your home.
Regulatory Standards for Trichlorofluoromethane
| Standard | Level | Notes |
|---|---|---|
| EWG Health Guideline | 1,300 ppb | Stricter, based on latest science |
| Average Detected Level | 1.71 ppb | Across all tested systems |
| Highest Detected Level | 40.70 ppb | Worst-case system |
Cities With the Highest Trichlorofluoromethane Levels
| # | City | Detected Level | People Served |
|---|---|---|---|
| 1 | Pauma Valley, CA | 40.70 ppb | 769 |
| 2 | Yakima, WA | 4.17 ppb | 192 |
| 3 | Marshall, WA | 1.02 ppb | 74 |
| 4 | Garden City, NY | 0.67 ppb | 46,000 |
| 5 | Hollister, CA | 0.66 ppb | 55 |
| 6 | Stamford, NY | 0.50 ppb | 44 |
| 7 | White, GA | 0.40 ppb | 900 |
| 8 | Huntington, NY | 0.38 ppb | 34,522 |
| 9 | Centerport, NY | 0.31 ppb | 81,760 |
| 10 | Perry, NY | 0.25 ppb | 4,348 |
| 11 | Silver Springs, NY | 0.25 ppb | 60 |
| 12 | Castile, NY | 0.25 ppb | 440 |
| 13 | Perry, NY | 0.25 ppb | 150 |
| 14 | La Crosse, WI | 0.15 ppb | 53,000 |
| 15 | Park Ridge, NJ | 0.15 ppb | 16,466 |
States Most Affected by Trichlorofluoromethane
How to Remove Trichlorofluoromethane From Your Water
CFC-11 is a volatile, lipophilic compound with good affinity for activated carbon. Standard pitcher filters with adequate carbon contact time can remove 60-80% of CFC-11, though complete removal requires extended-contact GAC or reverse osmosis.
Standard pitcher filters and carbon block filters can provide some reduction of Trichlorofluoromethane, though effectiveness varies by brand and flow rate. For maximum protection, a certified RO system is recommended.
Activated carbon is moderately effective due to volatility and lipophilicity; however, pitcher filters provide only partial removal. Reverse osmosis or GAC systems offer >95% removal.
Echo RO System
Removes Trichlorofluoromethane and 99.9% of other contaminants. The gold standard for drinking water purification.
View RO SystemsEcho Hydrogen Water Flask
Once your water is clean, supercharge it with molecular hydrogen for antioxidant benefits.
Shop Hydrogen FlaskFrequently Asked Questions
Is Trichlorofluoromethane in my drinking water?
Trichlorofluoromethane was detected in 30 water systems across the US. Check your city's water quality report to see if it affects your water supply.
What are the health effects of Trichlorofluoromethane in water?
Trichlorofluoromethane has been associated with various health concerns at elevated levels. The EWG has set health guidelines that are typically stricter than EPA legal limits.
Which city has the most Trichlorofluoromethane in its water?
Based on our analysis, Pauma Valley, CA has the highest detected levels of Trichlorofluoromethane in its water supply.
How do I remove Trichlorofluoromethane from my water?
Reverse osmosis (RO) systems are generally the most effective at removing this contaminant. Check the filtration recommendations section for specific guidance.
Related Contaminant Guides
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: September 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
