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

1,1,2-Trichloroethane: What It Is and Why It Matters

1,1,2-Trichloroethane is a synthetic chemical that doesn't occur naturally in the environment. Industries use it as a solvent to clean metal parts, manufacture other chemicals, and process certain plastics. It enters drinking water primarily through industrial discharge, improper waste disposal, and contaminated groundwater near manufacturing sites. Once it gets into soil, it moves easily into underground water supplies that many communities rely on for drinking water.

The health concerns around 1,1,2-trichloroethane are real, even at low levels. Animal studies show it can damage the liver and kidneys with repeated exposure. The EPA classifies it as a possible human carcinogen, meaning there's enough evidence to raise concern about cancer risk over a lifetime of exposure. Short-term exposure at high levels can cause dizziness, nausea, and central nervous system effects. Children and pregnant women face the greatest risk from long-term, low-level exposure, since their bodies are more vulnerable to chemical disruption.

Regulatory limits for this chemical tell an important story. The EPA's Maximum Contaminant Level (MCL) — the legal limit in public water — is set at 5 parts per billion (ppb). The average detected level in U.S. water systems sits at just 0.058 ppb, and the highest recorded amount in this dataset reached 0.25 ppb. Both figures fall well below the EPA's legal threshold. However, it's worth understanding that legal limits don't always equal safe limits. The EPA sets MCLs by balancing health risk against the cost of treatment — not purely on what's safest. No systems in this dataset tested above the health guideline, which is encouraging, but detected still means present.

Geographically, this contaminant shows up in a narrow set of states. Of the 18 water systems that detected 1,1,2-trichloroethane, 15 are in California and 3 are in New York. That's not a coincidence. Both states have dense industrial histories, with legacy manufacturing and chemical processing facilities that operated for decades before modern environmental regulations took hold. California's San Fernando Valley and parts of the Central Valley carry known groundwater contamination from industrial solvents — a problem that has taken years and billions of dollars to address. New York's industrial corridor along the Hudson Valley and Long Island carry similar histories. If you live in either state and draw from a well or a smaller municipal system, it's worth knowing whether this chemical has been detected in your water.

The good news is that 1,1,2-trichloroethane is very effectively removed through the right filtration methods. Activated carbon filtration — the kind used in many under-sink and whole-home systems — captures chlorinated solvents like this one. For the highest level of protection, reverse osmosis (RO) systems remove up to 99% of synthetic organic chemicals, including 1,1,2-trichloroethane. Echo Water's reverse osmosis systems are designed specifically to target this class of contaminants, giving you clean, filtered water straight from your tap. If you're on a municipal system, you can request your annual Consumer Confidence Report to check whether this chemical has been detected. If you're on a private well, independent testing is the only way to know for sure — and it's worth doing at least once a year.

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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