1,1,1,2-Tetrachloroethane in Drinking Water: Complete Guide (2026)

What is 1,1,1,2-Tetrachloroethane and Why Does It Matter?

# 1,1,1,2-Tetrachloroethane: What You Need to Know

## What It Is and Where It Comes From

1,1,1,2-Tetrachloroethane is a colorless liquid chemical once widely used as a refrigerant and solvent in industrial processes. You'll also see it called CFC-114a or Freon-114a. The chemical was particularly common in air conditioning systems, foam-blowing operations, and metal cleaning before environmental regulations phased out its use. When these systems leak or when contaminated industrial sites aren't properly managed, the chemical seeps into groundwater and eventually reaches municipal water supplies. Because it's dense and persistent in the environment, tetrachloroethane can travel significant distances underground before being detected.

The chemical is still occasionally released from older equipment that hasn't been properly decommissioned, and it can also form as a breakdown product when certain chlorinated solvents degrade in the environment. Once in the water system, it doesn't break down quickly, meaning contamination can persist for years.

## Health Effects and Exposure Risks

Exposure to 1,1,1,2-tetrachloroethane primarily affects the liver and central nervous system. Animal studies show that high doses can damage liver tissue and affect neurological function. The EPA classifies it as a possible human carcinogen based on laboratory evidence, though human cancer cases linked specifically to this chemical are rare. Short-term exposure to elevated levels may cause dizziness, headaches, and nausea. Long-term exposure at lower levels raises concerns about liver damage and potential cancer risk, particularly with prolonged consumption.

The good news: the average detection level in contaminated systems is just 1.153 ppb (parts per billion), which is relatively low. However, one water system tested as high as 26.0 ppb, which exceeds safe drinking water guidelines.

## Regulatory Standards and Guidelines

The EPA has not established a formal maximum contaminant level (MCL) for 1,1,1,2-tetrachloroethane, which means there's no federal drinking water standard that water utilities must meet. This regulatory gap exists partly because the chemical's use has declined significantly since the 1990s, making it a lower priority for EPA standard-setting. However, the Environmental Working Group (EWG) recommends a health guideline of 0.17 ppb based on cancer risk assessment. This means the one water system that tested at 26.0 ppb exceeded EWG's protective guideline by over 150 times.

Without an EPA mandate, water utilities aren't required to monitor for this contaminant, and many don't. This is why independent testing through services like Echo Water's water quality analysis is valuable—it catches chemicals that slip through regulatory cracks.

## Geographic Patterns and Why They Matter

The contamination shows a clear regional pattern, with Alabama accounting for 15 of the 26 detected cases. New York follows with 7 detections, while South Carolina, Georgia, and Wisconsin each have 1. Alabama's prevalence likely reflects the state's industrial history and the presence of older manufacturing facilities that used chlorinated solvents. The concentration in the Southeast and Northeast suggests these regions had higher densities of refrigeration and chemical manufacturing operations during the chemical's peak use in the 1970s and 1980s.

If you live in Alabama or upstate New York, it's worth asking your water utility whether they test for this contaminant. Many don't, even though the risk exists.

## How to Remove It From Your Water

Activated carbon filters can remove some tetrachloroethane, but they're not consistently reliable for this particular chemical. Reverse osmosis (RO) systems are far more effective, removing up to 99% of the contaminant. An Echo Water whole-home reverse osmosis system or point-of-use RO filter under your kitchen sink provides dependable protection. Distillation also works but is slower and more energy-intensive than RO.

If your water tests positive for this chemical, don't panic—but do act. Have your water professionally tested first to confirm levels, then install appropriate filtration. For most households, a reverse osmosis system represents the most practical and cost-effective solution.

Regulatory Standards for 1,1,1,2-Tetrachloroethane

Cities With the Highest 1,1,1,2-Tetrachloroethane Levels

States Most Affected by 1,1,1,2-Tetrachloroethane

Frequently Asked Questions

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