Trichloroethylene in Drinking Water: Complete Guide (2026)

What is Trichloroethylene and Why Does It Matter?

# Trichloroethylene (TCE): What You Need to Know

Trichloroethylene, or TCE, is a colorless chemical that smells like chloroform. It's been used for decades as a degreaser in manufacturing and dry cleaning, and as a solvent in electronics production. TCE enters groundwater through industrial spills, improper disposal, and leaking storage tanks. Once in the soil, it moves slowly downward, sometimes taking years to reach drinking water supplies. The EPA estimates that TCE contamination is one of the most common groundwater problems in the United States. If your home draws water from a private well or a municipal system near industrial areas, TCE testing should be part of your water quality routine.

The health risks from TCE exposure depend on how much you're exposed to and for how long. Short-term exposure to high levels can cause dizziness, headaches, and liver damage. Long-term exposure is the bigger concern for most families. The EPA classifies TCE as a probable human carcinogen (cancer-causing agent), and the International Agency for Research on Cancer agrees. Studies have linked TCE to kidney cancer, liver cancer, and non-Hodgkin's lymphoma. Additionally, some research suggests TCE exposure during pregnancy may affect fetal development. Even at low levels over many years, TCE poses a meaningful risk—which is why water testing matters.

Here's where regulatory standards get important. The EPA's legal limit for TCE in drinking water is 5 parts per billion (ppb). However, the Environmental Working Group (EWG), which sets health-based guidelines, recommends a much lower limit of 0.3 ppb. That's a 16-fold difference. Why? The EPA's standard is based partly on cost and feasibility of treatment, while the EWG focuses purely on health protection. Our data shows that 127 water systems across the United States exceed the EWG guideline, with maximum levels reaching 5.67 ppb—nearly 19 times the EWG recommendation. Even if your water meets EPA standards, it may still contain TCE at levels the EWG considers unsafe for long-term consumption.

California, New York, and Pennsylvania are hit hardest by TCE contamination. California alone has 87 water systems with TCE above the EWG guideline. This reflects the region's industrial history—California's Silicon Valley and aerospace manufacturing corridors have decades of TCE legacy contamination. New York's 42 affected systems cluster around manufacturing hubs and military bases, where TCE was historically used. Pennsylvania's 28 systems correlate with industrial sites in the Pittsburgh area and dry cleaning operations throughout the state. Alabama, Wisconsin, and other states round out the top five, typically in areas with military installations or aerospace manufacturing. If you live in these states, especially near industrial zones or military bases, TCE testing is essential.

Removing TCE requires serious filtration. Activated carbon filters can reduce TCE, but only if they're specifically designed and regularly replaced—standard pitcher filters won't work. Reverse osmosis systems remove up to 99.9% of TCE and are highly effective for drinking and cooking water. Air stripping (a process that bubbles air through water) works well for whole-house treatment but requires professional installation. The best choice depends on your water's TCE level and your budget. If testing shows TCE above 0.3 ppb, we recommend either a reverse osmosis system for your kitchen or a whole-house carbon filter designed specifically for TCE removal. Have your water tested first—you can't treat what you don't know is there.

Regulatory Standards for Trichloroethylene

Cities With the Highest Trichloroethylene Levels

States Most Affected by Trichloroethylene

Frequently Asked Questions

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