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Water: Basic Information about Regulated Drinking Water Contaminants

Basic Information about Asbestos in Drinking Water

Asbestos at a Glance

Maximum Contaminant Level (MCL) = 7 million fibers per Liter (MFL)

Maximum Contaminant Level Goal (MCLG) = 7 MFL

Health Effects
Some people who drink water containing asbestos in excess of the MCL over many years may have an increased risk of developing benign intestinal polyps.

Drinking Water Health Advisories provide more information on health effects

Chemical Abstract Service Registry Number

Sources of Contamination
Decay of asbestos cement in water mains; erosion of natural deposits

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

EPA regulates asbestos in drinking water to protect public health. Asbestos 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 asbestos?
Asbestos is a fibrous mineral occurring in natural deposits.

Uses for asbestos.
Because asbestos fibers are resistant to heat and most chemicals, they have been mined for use in more than 3,000 products, including roofing materials, brake pads, and cement pipe often used in distributing water to communities.

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

What are asbestos' health effects?
Some people who drink water containing asbestos well in excess of the maximum contaminant level (MCL) for many years may have an increased risk of developing benign intestinal polyps.

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

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What are EPA's drinking water regulations for asbestos?
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 asbestos is 7 MFL. 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 asbestos, called a maximum contaminant level (MCL), at 7 MFL. MCLsare 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. In this case, the MCL equals the MCLG, because analytical methods or treatment technology do not pose any limitation.

The Phase II Rule, the regulation for asbestos, became effective in 1992. 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 asbestos as part of the Six Year Review and determined that the 7 MFL MCLG and 7 MFL MCL for asbestos are still protective of human health.

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

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How does asbestos get into my drinking water?
The major sources of asbestos in drinking water are decay of asbestos cement water mains; and erosion of natural deposits.

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 asbestos is in my drinking water?
When routine monitoring indicates that asbestos levels are above the MCL, your water supplier must take steps to reduce the amount of asbestos 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 asbestos be removed from my drinking water?
The following treatment method(s) have proven to be effective for removing asbestos to below 7 MFL: coagulation/filtration, direct and diatomite filtration, and corrosion control.

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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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