Jump to main content or area navigation.

Contact Us

Water: Basic Information about Regulated Drinking Water Contaminants

Basic Information about Alachlor in Drinking Water

Alachlor at a Glance

Maximum Contaminant Level (MCL) = 0.002 milligrams per Liter (mg/L) or 2 parts per billion (ppb)

Maximum Contaminant Level Goal (MCLG) = zero

Health Effects
Some people who drink water containing alachlor in excess of the MCL over many years could have problems with their eyes, liver, kidneys, or spleen, or experience anemia, and may have increased risk of getting cancer.

Drinking Water Health Advisories provide more information on health effects

Chemical Abstract Service Registry Number

Sources of Contamination
Runoff from herbicide used on row crops

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

EPA regulates alachlor in drinking water to protect public health. Alachlor 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 alachlor?
Alachlor is an odorless white solid.

Uses for alachlor.
Alachlor is used as an herbicide for control of annual grasses and broadleaf weeds in crops, primarily on corn, sorghum, and soybeans.

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

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

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

Top of page

p>What are EPA's drinking water regulations for alachlor?
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 alachlor 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 alachlor, called a maximum contaminant level (MCL), at 0.002 mg/L or 2 ppb. 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.

The Phase II Rule, the regulation for alachlor, 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 alachlor as part of the Six Year Review and determined that the zero MCLG and 0.002 mg/L or 2 ppb MCL for alachlor are still protective of human health.

States may set more stringent drinking water MCLGs and MCLsfor alachlor than EPA.

Top of page

p>How does alachlor get into my drinking water?
The major source of alachlor in drinking water is runoff from herbicide used on row crops.

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.

Top of page

p>How will I know if alachlor is in my drinking water?
When routine monitoring indicates that alachlor levels are above the MCL, your water supplier must take steps to reduce the amount of alachlor 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.

Top of page

br> How will alachlor be removed from my drinking water?
The following treatment method(s) have proven to be effective for removing alachlor to below 0.002 mg/L or 2 ppb: granular activated carbon.

Top of page

p>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.

Other EPA websites

Top of page

Jump to main content.