Chromium in Drinking Water

During the fall of 2016, there has been increased media attention placed on the detection of chromium in public water systems across the country.  In keeping with Concord Public Works’ Water and Sewer Division’s commitment to provide all of our customers with the most current and accurate water quality information available, we offer you the following summary of drinking water concerns, local and national standards (and goals), and water quality test results for samples that have been collected from within Concord’s public water system.  

Contaminant Summary


Chromium is a tasteless, odorless chemical compound that occurs naturally in the environment in rocks, soil and plants, and in volcanic dust and gases. It is present in several different forms, including chromium-0 (metal form), chromium-3 (trivalent form) and chromium-6 (hexavalent form). Some forms of chromium are actually beneficial to humans; for example, chromium-3 is recognized as an essential human nutrient and is found in common foods as well as vitamins and other nutritional supplements. 

Chromium-6 is most widely found as a component of coloring pigment used in paints, dyes, inks and plastics, and is often added as an anticorrosive agent to paints, primers and other surface coatings. Chromium-6 is also found in chromic acid, used in the electroplating of metal parts to provide a protective or decorative coating. In industrial applications, chromium-6 is typically produced as a result of welding on stainless steel, or the melting of chromium metal, when extremely high temperatures convert chromium to a hexavalent state.

Chromium Limits

Federal –  The federal drinking water standard Maximum Contaminant Level (MCL) for total chromium is 0.1 mg/L or 100 parts per billion (ppb). Chromium-6 and chromium-3 are covered under the total chromium drinking water standard because these forms of chromium can convert back and forth in water and in the human body, depending on environmental conditions.[2] 

Massachusetts – Massachusetts regulatory agencies follow the federal guidance for total chromium.  At this time, the Massachusetts Department of Public Health and the Massachusetts Department of Environmental Protection have not indicated that they are planning on setting a drinking water limit less than the federal standard of 0.1 mg/L or 100 parts per billion (ppb) for total chromium or establishing a chromium-6 limit. 

California – The California drinking water standard Maximum Contaminant Level (MCL) for total chromium is 0.05 mg/L or 50 parts per billion (ppb), with a chromium-6 MCL of 0.01 mg/L or 10 ppb for chromium-6 in drinking water. California has set the only drinking water standard for chromium-6 in the nation. California has set a Public Health Goal of 0.00002 mg/L or 0.02 ppb for chromium-6, which is the estimated “one in a million” lifetime cancer risk level. This means that for every million people who drink two liters of water with that level of hexavalent chromium daily for 70 years, no more than one person would be expected to develop cancer from exposure to hexavalent chromium.[3]

Unregulated Contaminant Testing in Concord, MA

Summary of Chromium Limits


Federal Total Chromium Limit (MCL) – 100 ppb

California Total Chromium Limit (MCL) – 50 ppb

California Chromium-6 Limit (MCL) – 10 ppb

Concord Chromium-6 Drinking Water Samples – 0.03-0.17 ppb

California Chromium-6 Public Health Goal (PHG) – 0.02 ppb

  1. Melissa Simoncini


Occurrence of Chromium-6 in Massachusetts Water Supplies

During 2014, Concord Water and Sewer participated in the third round of the Federal Unregulated Contaminant Monitoring Rule (UCMR3) monitoring program (2013-2015).  This sampling was performed in conjunction with many other Public Water Suppliers in the United States.  Approximately 90% of the Massachusetts Public Water Systems detected the presence of chromium-6 above 0.03 mg/L or 30 parts per billion (ppb)[4].  Chromium-6 was identified in Concord’s drinking water at 0.03-0.17 ppb, as referenced in the 2015 Annual Water Quality Report[5]. While it is difficult for many people to relate to such small numbers, one part per billion would be less than one teaspoon of water in an Olympic-sized swimming pool.  The levels measured in Concord’s water supply were less than 0.5% of both California’s chromium-6 MCL and the federal standard for total chromium.  

Concord is monitoring the emerging science on total chromium and chromium-6 and will follow the recommendations set forth by the Massachusetts Department of Public Health and Massachusetts Department of Environmental Protection. 

For questions about Drinking Water Quality, please contact Concord Water and Sewer Division 

[1] Hexavalent Chromium in Drinking Water: A Review of Regulations and Testing Procedures, Underwriters Laboratory (Accessed 9/26/16) 

[2] Chromium in Drinking Water, USEPA (Accessed 9/26/16) 

[3] Chromium in Drinking Water: A Technical Information Primer, American Water Works Association (Accessed 9/26/16) 

[4] The Third Unregulated Contaminant Monitoring Rule (UCMR 3): Data Summary July 2016, US EPA (Accessed on 9/27/16) & Occurrence Data for the Unregulated Contaminant Monitoring Rule, USEPA (Accessed 9/27/16)

[5] 2015 Annual Water Quality Report, Town of Concord MA - (Accessed 9/27/16)

This page was published on September 29, 2016