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Water: Basic Information about Regulated Drinking Water Contaminants

Basic Information about Trichloroethylene in Drinking Water

Trichloroethylene at a Glance

Maximum Contaminant Level (MCL) = 0.005 milligrams per Liter (mg/L) or 5 parts per billion (ppb)

Maximum Contaminant Level Goal (MCLG) = zero

Health Effects
Some people who drink water containing trichloroethylene in excess of the MCL over many years could experience problems with their liver and may have an increased risk of getting cancer.

Drinking Water Health Advisories provide more information on health effects

Chemical Abstract Service Registry Number
79-01-6

Sources of Contamination
Discharge from metal degreasing sites and other factories

List of all Regulated Contaminants (PDF) (6 pp, 396K, About PDF)

EPA regulates trichloroethylene in drinking water to protect public health. Trichloroethylene may cause health problems if present in public or private water supplies in amounts greater than the drinking water standard set by EPA.

What is trichloroethylene?
Trichloroethylene, a volatile organic chemical, is a colorless or blue liquid with a chloroform-like odor.

Uses for trichloroethylene.
Trichloroethylene is primarily used to remove grease from fabricated metal parts and in the production of some textiles.

If you are concerned about trichloroethylene in a private well, please visit:

What are trichloroethylene's health effects?
Some people who drink water containing trichloroethylene well in excess of the maximum contaminant level (MCL) for many years could experience problems with their liver and may have an increased risk of getting cancer.

This health effects language is not intended to catalog all possible health effects for trichloroethylene. Rather, it is intended to inform consumers of some of the possible health effects associated with trichloroethylene in drinking water when the rule was finalized.

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What are EPA's drinking water regulations for trichloroethylene?
In 1974, Congress passed the Safe Drinking Water Act. This law requires EPA to determine the level of contaminants in drinking water at which no adverse health effects are likely to occur. These non-enforceable health goals, based solely on possible health risks and exposure over a lifetime with an adequate margin of safety, are called maximum contaminant level goals (MCLG). Contaminants are any physical, chemical, biological or radiological substances or matter in water.

The MCLG for trichloroethylene is zero. EPA has set this level of protection based on the best available science to prevent potential health problems. EPA has set an enforceable regulation for trichloroethylene, called a maximum contaminant level (MCL), at 0.005 mg/L or 5 ppb. MCLs are set as close to the health goals as possible, considering cost, benefits and the ability of public water systems to detect and remove contaminants using suitable treatment technologies.

The Phase I Rule, the regulation for trichloroethylene, became effective in 1989. The Safe Drinking Water Act requires EPA to periodically review the national primary drinking water regulation for each contaminant and revise the regulation, if appropriate. EPA reviewed trichloroethylene as part of the second Six Year Review and determined that it is appropriate to revise the regulation based on changes in analytical feasibility.

States may set more stringent drinking water MCLGs and MCLs for trichloroethylene than EPA.

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How does trichloroethylene get into my drinking water?
The major source of trichloroethylene in drinking water is discharge from metal degreasing sites and other factories. Wastewater from metal finishing, paint and ink formulation, electrical components, and rubber processing industries may also contain trichloroethylene.

A federal law called the Emergency Planning and Community Right to Know Act (EPCRA) requires facilities in certain industries, which manufacture, process, or use significant amounts of toxic chemicals, to report annually on their releases of these chemicals. For more information on the uses and releases of chemicals in your state, contact the Community Right-to-Know Hotline: (800) 424-9346.

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How will I know if trichloroethylene is in my drinking water?
When routine monitoring indicates that trichloroethylene levels are above the MCL, your water supplier must take steps to reduce the amount of trichloroethylene so that it is below that level. Water suppliers must notify their customers as soon as practical, but no later than 30 days after the system learns of the violation. Additional actions, such as providing alternative drinking water supplies, may be required to prevent serious risks to public health.

If your water comes from a household well, check with your health department or local water systems that use ground water for information on contaminants of concern in your area.

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How will trichloroethylene be removed from my drinking water?
The following treatment method(s) have proven to be effective for removing trichloroethylene to below 0.005 mg/L or 5 ppb: granular activated carbon in combination with packed tower aeration.

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How do I learn more about my drinking water?
EPA strongly encourages people to learn more about their drinking water, and to support local efforts to protect the supply of safe drinking water and upgrade the community water system. Your water bill or telephone book's government listings are a good starting point for local information.

Contact your water utility. EPA requires all community water systems to prepare and deliver an annual consumer confidence report (CCR) (sometimes called a water quality report) for their customers by July 1 of each year. If your water provider is not a community water system, or if you have a private water supply, request a copy from a nearby community water system.

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