Editor’s note: Starting with this issue, Water Technology® will provide each month basic information about a contaminant found in water sources. The contaminant may not necessarily be found in all geographic locations or situations, or at levels sufficient to raise concern.

Chemical formula: C2HCl3
Molecular weight: 131.40
Molecular structure:



Physical characteristics:

• Clear, colorless, nonflammable volatile organic compound (VOC), one of the chlorinated solvents
• Liquid at room temperature
• Sweet, chloroform-like odor
• Density at 20°C (68°F) = 1.465 grams per liter (heavier than water)

Where found: TCE is not believed to occur naturally in the environment, but may be found in groundwater and surface water following its manufacture, use and disposal. Most common in industrial and urban areas.

It was the fourth most frequently detected VOC in US groundwaters (2006).

Common uses: Solvent for cleaning and degreasing metals; ingredient in adhesives, paint removers, typewriter correction fluids and spot removers; chemical-process intermediate for making other products. Known by a number of synonyms (such as trichloroethene and acetylene trichloride) and many trade names.

Potential health effects: Can cause liver and kidney damage, and other ailments. “Probably carcinogenic to humans” (International Agency for Research on Cancer).

Regulation:

• US EPA Maximum Contaminant Level (MCL) in drinking water: 5 parts per billion (ppb) (0.005 milligrams per liter[mg/L]).
• US EPA MCL Goal: zero.
• Selected state MCLs: California, 5 ppb; Arizona, 3.2 ppb; New Jersey, 1 ppb.
• Listed as hazardous substance and toxic pollutant under federal pollution control laws.

Common water treatment methods:

• POU/POE: Activated carbon adsorption, reverse osmosis (latter removes 70 to 80 percent)
• Other: Air stripping (groundwater remediation)
  

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Sources: US Environmental Protection Agency (EPA), US Agency for Toxic Substances & Disease Registry, US Geological Survey, Water Quality Association, industry sources.