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Water: Basic Information about Regulated Drinking Water Contaminants

Basic Information about Carbon Tetrachloride in Drinking Water

Carbon Tetrachloride 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 carbon tetrachloride 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
56-23-5

Sources of Contamination
Discharge from chemical plants and other industrial activities

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

EPA regulates carbon tetrachloride in drinking water to protect public health. Carbon tetrachloride 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 carbon tetrachloride?
Carbon tetrachloride is a clear heavy organic liquid with a sweet aromatic odor similar to chloraform.

Uses for carbon tetrachloride.
Most carbon tetrachloride is used to make chlorofluorocarbon propellants and refrigerants, though this has been declining steadily. It has also been used as a dry cleaning agent and fire extinguisher; in making nylons; as a solvent for rubber cement, soaps, insecticides, etc.

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

What are carbon tetrachloride's health effects?
Some people who drink water containing carbon tetrachloride 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 carbon tetrachloride. Rather, it is intended to inform consumers of some of the possible health effects associated with carbon tetrachloride in drinking water when the rule was finalized.

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What are EPA's drinking water regulations for carbon tetrachloride?
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 carbon tetrachloride 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 carbon tetrachloride, 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 carbon tetrachloride, 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 carbon tetrachloride as part of the Six Year Review and determined that the zero MCLG and 0.005 mg/L or 5 ppb MCL for carbon tetrachloride are still protective of human health.

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

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How does carbon tetrachloride get into my drinking water?
The major sources of carbon tetrochloride in drinking water are discharge from chemical plants and other industrial activities.

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 carbon tetrachloride is in my drinking water?
When routine monitoring indicates that carbon tetrachloride levels are above the MCL, your water supplier must take steps to reduce the amount of carbon tetrachloride 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 carbon tetrachloride be removed from my drinking water?
The following treatment method(s) have proven to be effective for removing carbon tetrachloride 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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