With recent concerns within the news media about the chemical compound called Chromium-6 in the drinking water, Prestonsburg City’s Utilities Commission would like to help our customers understand more about this compound and try to explain the regulations we are to adhere by through the state and federal agency’s dealing with this particular chemical compound. Below we have provided a few possible questions that our customers may ask along with an explanation.


Recent news indicates that my water does contain dangerous levels of Chromium-6. How dangerous are the levels in my water?

Chromium-6 is one of the more common forms of Chromium. Under EPA regulations, Chromium-6, along with other forms of Chromium, is covered under the Total Chromium drinking water standard in which Prestonsburg City’s Utilities Commission does test for annually.

Total Chromium MCL (Maximum Containment Level) is 0.1 ppm or 100 ppb. Prestonsburg City’s Utilities Commission’s result for Total Chromium for 2016 was 0.001 ppm. Our test result is 1,000 times under the MCL for Total Chromium.

To understand some of the terminology in the statement above, we have provided definitions for clarification below:

  • Parts Per Million (PPM) – One part per million corresponds to one minute in two years or a single penny in $10,000
  • Parts Per Billion (PPB) – One part per billion corresponds to one minute in 2,000 years or a single penny in $10,000,000.
  • Maximum Contaminant Level (MCL) – The highest level of contaminant that is allowed in drinking water. MCLs are set as close to MCLGs using the best available treatment technology.
  • Maximum Contaminant Level Goal (MCLG) – The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety.

     MCLs for any contaminate are set at very stringent levels. To understand the possible health effect described for many regulated contaminants, a person would have to drink 2 liters of water every day at the MCL level for a lifetime to have one-in-a-million chance of having the described health effect.


In the article, it states that our water tested positive for Chromium-6 and that Prestonsburg water’s average for Chromium-6 is above the California Public Health Goal. Why is Prestonsburg’s water above the California Public Health Goal?

The samples tested for Chromium-6 in our water system was part of the EPA’s Third Unregulated Contaminant Monitoring Regulation (UCMR 3) which was completed in 2014. The 1996 Safe Drinking Water Act (SDWA) amenments require that once every five years EPA issue a new list of no more than 30 unregulated contaminants to be monitored by public water systems. The UCMR3 required monitoring 30 contaminants between 2013 and 2015 using analytical methods developed by EPA, consensus organizations or both. This monitoring provides a basis for future regulatory actions to protect public health.  https://www.epa.gov/dwucmr/third-unregulated-contaminant-monitoring-rule

At this time, EPA does not regulate specifically Chromium-6 therefore there is no federal drinking water standard for the contaminant. EPA does consider Chromium-6 and Chromium-3 covered under the Total Chromium that is tested yearly for all public water systems.

” The current federal drinking water standard for Total Chromium is 0.1 ppm or 100 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. Measuring just one form may not capture all of the chromium that is present. In order to ensure that the greatest potential risk is addressed, EPA’s regulation assumes that a measurement of Total Chromium is 100 percent chromium-6, the more toxic form. If tap water from a public water system exceeds this federal standard, consumers will be notified.”   https://www.epa.gov/dwstandardsregulations/chromium-drinking-water

The California Public Health Goal (CPHG) for Chromium-6 stated in the article was established by and for the state of California. California is the only state that has set MCL’s for Chromium-6 at 10 ppb and their CPHG at 0.02 ppb although the EPA has not set a MCL specifically for this particular contaminate. If Prestonsburg City’s Utilities Commission is to compare our results with California’s drinking water regulations, our average results is 0.029 ppb compared to California’s MCL of 10 ppb. California’s Public Health Goal of 0.02 is just a goal they wish to reach and is not enforceable. http://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/Chromium6.shtml


What are Total Chromium and /or Chromium-6?

Chromium is an odorless and tasteless metallic element. It is found naturally in rocks, plants, soil and volcanic dust, and animals. Most common forms of chromium that occur in natural waters in the environment are Trivalent Chromium (Chromium-3) and Hexavalent Chromium (Chromium-6).

Chromium-3 is an essential human dietary element. It is found in many vegetables, fruits, meats, grains, and yeast. Chromium-6 occurs naturally in the environment from the erosion of natural chromium deposits. It can also be produced by industrial process. There are demonstrated instances of chromium being released to the environment by leakage, poor storage, or inadequate industrial waste disposal practices.

Total Chromium is a measurement of all forms of chromium, including Chromium-6 and Chromium-3.



What was Prestonsburg City’s Utilities Commission test results of Chromium-6 in the drinking water?

As part of EPA’s assessment of determining the level of Chromium-6 in drinking water, Prestonsburg City’s Utilities Commission was selected to test Chromium-6 under the UCMR 3 (Third Unregulated Contaminant Monitoring Regulation) in 2014. The following was our results:

DATE Sample Point Result
1/14/2014 Prestonsburg Water Treatment Plant (EPTDS) 0.035 ppb
Furthest Point within Distribution System 0.0.36 ppb
4/1/2014 Prestonsburg Water Treatment Plant (EPTDS) 0.034 ppb
Furthest Point within Distribution System 0.049 ppb
7/29/2014 Prestonsburg Water Treatment Plant (EPTDS) No Detect
Furthest Point with Distribution System 0.034 ppb
10/14/2014 Prestonsburg Water Treatment Plant (EPTDS) No Detect
Furthest Point within Distribution System 0.045 ppb

The average sample results of  Chromium-6 is 0.029 ppb.