Information on Hexavalent Chromium
Please refer to Page 18 of Loudoun Water’s Annual Drinking Water Quality Report for information on Hexavalent Chromium and other unregulated contaminants.

Is there Hexavalent Chromium (Cr6) in our drinking water?

•             Drinking water in our region has minute levels of Cr6.

•             Regional distribution system Cr6 levels measured in the range from non-detectable (ND) to 1.11 ppb.

•             Distribution system test results are closest to the level of Cr6 expected at the tap.

•             Water utilities test for Cr6 in source water at the intake and in treated drinking water.


Do regional water utilities meet the California Hexavalent Chromium MCL?

•             Regional utilities Cr6 levels measured in the water going to your tap are well below California MCL of 10.0 ppb.

•             The highest Cr6 level detected in regional distribution systems was just above 1.0 ppb.

•             The California maximum contaminant level (MCL) is 10.0 ppb of cr6 in drinking water

•             California water utilities must comply the 10.0 ppb MCL, the enforceable level in California regulations.

•             California officials used the Cr6 Pubic Health Goal if 0.02 ppb as the basis for the enforceable Cr6 regulation and 10.0 ppb MCL.


Is there a health risk to if my drinking water is above the California PHG?

A PHG is not a boundary line between a “safe” and “dangerous” level of a chemical, and drinking water is frequently demonstrated as safe to drink even if it contains chemicals at levels exceeding their PHGs. California Office of Environmental Health Hazard Assessment (OEHHA)

•             A drinking water sample with a Cr6 level above the Public Health Goal (PHG) of 0.02 ppb does not necessarily represent a health concern.

•             The PHG accounts for susceptible stages in life, including infants. The protection factors account for age and use higher rates of water consumption.

•             The 0.02 ppb PHG level is set expect no adverse health effects in a lifetime. If a group of one million people drank 2 liters of water every day for 70 years at this level, one cancer case would be expected.


What is Hexavalent Chromium?

•             Chromium is a metal found in rocks, soil, plants, and animals.

•             Chromium has three common forms: trivalent (Cr3), hexavalent (Cr6) and elemental (Cr0).

•             Cr3 is an essential micronutrient in the diet.

•             Inhaled Cr6 is a known health risk and carcinogen.

•             Chromium is used in steel making, metal plating, leather tanning, paints, dyes and wood preservatives.


How does Hexavalent Chromium get into drinking water?

•             Hexavalent Chromium enters water supplies naturally from water interacting with rocks and soil.

•             Industrial facilities, such as coal burning power plants, discharge water contaminated with Cr6.

•             Groundwater has higher natural levels of Cr6 than water from rivers and reservoirs.

•             The majority of drinking water in the region comes from the Potomac River.


How could I be exposed to Hexavalent Chromium?

•             Exposure can occur by breathing fumes, direct skin contact, eating contaminated food, or drinking contaminated water.

•             People working in industries that process or use chromium and chrome compounds, such as spray paints, coatings, chrome plating, metal cutting or welding have a higher risk of exposure.


Is there treatment to get Hexavalent Chromium out of drinking water?

•             Standard drinking water treatment reduces the low levels of Cr6 in source water to minute levels in tap water.

•             Advanced treatment technology is used for drinking water with very high Cr6 levels.

•             These treatment options include ion exchange, biological filtration and reverse osmosis.


Is there a test for tap water in my home?

•             Most commercial laboratories don’t offer a home test for Cr6.

•             If you are concerned, read your water utility’s annual water quality report (CCR).

•             Call your water system if you have questions about Cr6 in your drinking water.


Is Hexavalent Chromium regulated in drinking water?

•             EPA regulates Total Chromium in drinking water and set the standard in 1992. The level is based on risk of allergic dermatitis (skin reactions).

•             The Total Chromium MCL is 100.0 ppb and includes Cr3 and Cr6.

•             Hexavalent Chromium drinking water testing is required by EPA for the UCMR (Unregulated Contaminant Monitoring Rule).


What is the difference between Total Chromium and Hexavalent Chromium?

•             Total Chromium measurements includes Cr6 and Cr3.

•             Chromium converts back and forth between Cr3 and Cr6.

•             Cr3 is an essential nutrient in the diet and has low toxicity.

•             Cr6 is more toxic and is known to cause cancer when inhaled.

•             The two forms of chromium convert back and forth in in the human body and in water under different environmental conditions. It is challenging to regulate Cr6 because the two convert.


Why are the California and EPA standards different?

•             The California legislature required the state to regulate Cr6 in drinking water and issue an MCL in 2001.

•             California agencies develop a Public Health Goal (PHG) to develop a drinking water regulation and define the MCL The PHG was set at 0.02 ppb in 2011

•             California became the first state to set a maximum contaminant level (MCL) for hexavalent chromium of 10.0 ppb in 2014.

•             EPA does not currently regulate Cr6 separately from Total Chromium. EPA is considering a new regulation for Cr6.

•             The EPA drinking water standard for Total Chromium is 100.0 parts per billion (ppb).

•             If EPA decides to regulate Cr6 they first set an Maximum Contaminant Level Goal and (MCLG). An EPA MCLG is equivalent to a California PHG. EPA will used the MCLG and a risk assessment to set and MCL.

•             An EPA MCL is a national standard and is enforceable throughout the US. The EPA MCL is set in a process similar to the California MCL.


Will the EPA issue a Hexavalent Chromium regulation?

EPA is the process of deciding on a Cr6 regulation, which includes:

•             National Toxicology Program data and studies

•             Integrated Risk Information System risk characterization;

•             Occurrence rates of CR6 in source water and drinking water;

•             Technology, feasibility and cost analysis.

The risk characterization combined with the other data informs the EPA decision to regulate any contaminant under the Safe Drinking Water Act.

What Is a Public Health Goal (PHG)?

•             A PHG is the level of a chemical contaminant in drinking water that does not pose a significant health risk.