Hexavalent Chromium
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Hexavalent chromium is one of the chemical forms of chromium, which can be present in different forms in the environment, changing from one form to another in water and soil. Hexavalent chromium is also commonly called chromium 6, chromium VI, chrome 6, Cr(VI), Cr+6 or hex chrome. It is also sometimes referred to as the “Erin Brockovich chemical,” because it was made famous in the 2000 movie “Erin Brockovich.” The film is a dramatization of a groundwater contamination incident in Hinkley, Calif., and a class-action lawsuit against an electric power company that resulted in a large settlement.

Other common forms of chromium are trivalent chromium, also known as chromium 3, and the metal form, chromium 0. Chromium can convert between chromium-3 and chromium-6 in different environments.

Hexavalent chromium exposure can occur by breathing it in, ingesting it in food or water, or through direct contact with the skin. People may be exposed to hexavalent chromium working in industries that process or use chromium, chromium compounds, or chromium processes, such as chromate containing pigments, spray paints, coatings, chrome plating baths, metal (such as stainless steel) cutting or welding, etc. Hexavalent chromium can be found in low levels in water supplies either as the result of industrial activities or from naturally occurring sources.

Water systems manage hexavalent chromium levels by controlling total chromium levels. The existing federal standard set by the U.S. Environmental Protection Agency for total chromium was set in 1992 and was set at the protective level indicated by the science at the time. The health effect the standard addresses is based on allergic dermatitis (skin reactions).

The question today is do lower concentrations of hexavalent chromium in drinking water present additional risks? To answer that question, EPA is now reviewing data from a 2008 National Toxicology Program long-term animal study, which suggests that hexavalent chromium may be a human carcinogen if ingested, as well as more recent research into why hexavalent chromium is toxic in animal studies. When the review is complete, EPA will consider this and other information to determine whether the drinking water standard for total chromium needs to be updated and whether a new hexavalent chromium standard is appropriate.

Currently, all water systems test for “total chromium.” In other words, they test for chromium in all its forms, including hexavalent chromium, but in most cases, not separately for hexavalent chromium. If the amount of total chromium in your tap water exceeds regulations set under the Safe Drinking Water Act, your water system will notify you.

Your water system publishes the results of total chromium tests in a consumer confidence report each year and makes that report publicly available. The report is often available on the internet, but you may also contact your water provider to request a printed copy. You can usually find contact information for your public water system on your water bill.

Hexavalent chromium is not currently regulated separately from total chromium. The drinking water standard for total chromium, which includes hexavalent chromium, is 100 parts per billion. A part per billion is equal to roughly one second in 32 years.

Hexavalent chromium has been in the news lately because it is being considered by some states and EPA for regulation separately from total chromium, and it is one of the contaminants that was included in EPA’s Third Unregulated Contaminant Monitoring Rule testing. EPA is currently evaluating hexavalent chromium through its Integrated Risk Information System, a process that characterizes the potential health risks based on the best available science. This risk characterization informs decisions about whether to move forward on regulations under the Safe Drinking Water Act. If EPA decides to regulate hexavalent chromium following the UCMR3 testing process, a rule would probably not be finalized for a few years.

In July 2014, California became the first U.S. state to determine a maximum contaminant level (MCL) specifically for hexavalent chromium of 10 parts per billion.

If you get your drinking water from a private well, you should have your water tested by a certified laboratory at least once a year. You can find information on how to sample for hexavalent chromium and where to send samples for analysis by contacting your state water laboratory certification officer. Contact information for your state can be found on EPA’s drinking water lab certification page. Additional information about well water testing from EPA is available on their private drinking water well FAQ page

If you are concerned about hexavalent chromium in your drinking water, you may consider purchasing a home treatment device. However, in order to make a well-informed and cost-effective decision, consider:
  • Checking with your water system or consumer confidence report to learn about the amount of total hexavalent chromium in your water.
  • Identifying a device that has been independently certified to remove hexavalent chromium.
NSF International, the Water Quality Association, Underwriters Laboratories and CSA International all certify home treatment products for removal of contaminants. The relevant hexavalent chromium removal standard is NSF/ANSI Standard 58. If you choose to use a home treatment device, it is very important to follow the manufacturer's operation and maintenance instructions carefully in order to make sure the device works properly.
Bottled water quality can vary. Bottled water in the United States is regulated by the U.S. Food and Drug Administration and is required to meet standards equal to the EPA’s tap water standards. There are also individual state standards. However, in most cases, you must contact the bottled water manufacturer for information about chromium levels.