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

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

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

## What It Is and Where It Comes From

1,1,2-Trichloroethane is a colorless liquid chemical that was widely used in industrial processes throughout the 20th century. It served as a solvent in dry cleaning, metal degreasing, and pesticide production. Though the EPA phased out most uses in the 1980s, this chemical remains stubbornly present in groundwater across the country.

The problem is persistence. Once 1,1,2-trichloroethane enters soil or groundwater, it breaks down very slowly. Contamination typically stems from three sources: leaking underground storage tanks at old industrial sites, improper disposal of manufacturing waste, and runoff from contaminated soil. When water systems draw from affected groundwater aquifers, the chemical travels directly into your tap. Currently, 41 water systems across the U.S. have detected this contaminant, with 4 systems exceeding health-based guidelines.

## Health Effects and Exposure Risks

Exposure to 1,1,2-trichloroethane poses real health concerns, particularly with long-term drinking water exposure. The EPA classifies it as a probable human carcinogen based on animal studies showing liver and kidney damage. The agency also notes potential effects on the nervous system with repeated exposure.

The health risk depends on concentration and duration. At low levels (below 0.05 ppb), the risk is minimal. However, the maximum level detected in U.S. water systems reached 0.5 ppb—10 times higher. The Environmental Working Group (EWG) sets a stricter health guideline of 0.07 ppb for drinking water, meaning some contaminated systems exceed even this protective threshold. Children and pregnant women face higher vulnerability because their bodies are still developing.

## Regulatory Standards and Guidelines

The EPA's maximum contaminant level (MCL) for 1,1,2-trichloroethane is 0.005 mg/L, or 5 ppb. This is the legal limit water utilities must meet. However, the EWG's health-based guideline is significantly stricter at 0.07 ppb, reflecting what scientists consider truly safe for lifetime exposure without increased cancer risk.

This gap matters. Four of the 41 affected water systems detected levels above the EWG guideline, suggesting inadequate protection under current EPA standards alone. Water utilities are required to notify customers when MCL violations occur, but many people don't realize their water exceeds the more protective EWG threshold.

## Geographic Hotspots

California leads with 19 detected systems, followed by Florida with 10 and New York with 6. The remaining cases appear in Idaho and South Carolina. California's prevalence reflects decades of industrial activity, particularly in the Central Valley and coastal manufacturing regions where groundwater contamination from mid-century dry cleaning and metal processing remains widespread. Florida's cases cluster in areas with shallow aquifers vulnerable to industrial seepage. New York's detections align with historical industrial zones around the Hudson River valley and Buffalo area.

## Removing It From Your Water

Standard water pitcher filters won't remove 1,1,2-trichloroethane effectively. You need a filtration system specifically designed for volatile organic compounds (VOCs).

Activated carbon filters work well for this contaminant, though they require regular replacement—typically every 6 months for whole-house systems. Reverse osmosis systems remove up to 99% of 1,1,2-trichloroethane and are highly effective for drinking water at the point of use. If your water system reports this chemical, ask for their latest water quality report, then choose a certified filter tested for VOC removal.

For the most comprehensive protection, consider having your water tested independently. Echo Water's testing can identify whether your specific water source contains this chemical and recommend the right filtration solution for your home.

Regulatory Standards for 1,1,2-Trichloroethane

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

States Most Affected by 1,1,2-Trichloroethane

Frequently Asked Questions

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