Chromium

A report released by the Environmental Working Group on December 20, 2010, spurred national interest in chromium in drinking water. Fairfax Water wanted to take the opportunity to answer some of the most common questions regarding the topic.

What is chromium?
Chromium is the 24th element on the periodic table. It is a naturally occurring metal found in soils, plants, rocks, water, and animals.

There are two common forms: Chromium III and Chromium VI.

• Chromium III is an essential human dietary element found in vegetable, meats, fruits, grains and yeast.
   

• Chromium VI, also known as hexavalent chromium, is generally produced by industrial processes such as steel manufacturing and pulp mills. It can also be generated by converting natural deposits of chromium III to chromium VI.

Has Fairfax Water tested for hexavalent chromium (chromium VI)?
Yes. Fairfax Water has conducted testing for hexavalent chromium in our raw (untreated) and finished (treated) waters.

What did you find?
We found extremely low amounts of hexavalent chromium in the raw and treated waters.

We did not find hexavalent chromium in the water that comes from the Occoquan Reservoir:

• Occoquan Reservoir Raw = <0.05 parts per billion (ppb)

• Griffith Finished = <0.05 ppb

We found extremely low amounts of chromium VI In the water that comes from the Potomac River:

• Potomac River Raw = 0.05 ppb

• Corbalis Finished = 0.06 ppb

The water delivered to your home may be from either the Occoquan Reservoir, the Potomac River or a combination of both sources.

What do these amounts mean?
The hexavalent chromium detected was found at the part per trillion and low part per billion levels. The ability to test compounds in water to these minute levels is relatively new. A part per billion is equivalent to 1 gallon of water in 1,514 Olympic size swimming pools. A part per trillion is equivalent to 1 gallon of water in 1,514,570 Olympic size swimming pools.

The analytical methods used in this study have very low detection levels—typically 100 to 1,000 times lower than State and Federal standards and guidelines for protecting water quality. These findings complement ongoing drinking-water monitoring required by Federal, State regulations.

Should I be concerned about the amount you found?
No. While there is not currently a standard for hexavalent chromium (chromium VI), we do know that these very low levels are not an acute health risk.

The risks discussed by the Environmental Protection Agency (EPA) and the proposed California Public Health Goal are based on a life-time exposure to hexavalent chromium.

• When EPA studies a compound for long-term risk, they use the assumption that everyone is drinking 2 liters of water every day for 70 years.

Scientists are working to understand the risks from hexavalent chromium. A study by the EPA is currently under review and will be released later this year.

What is Fairfax Water doing?
We test our water quarterly for total chromium. Our water is consistently below the detection limit for total chromium (<5 ppb).

To view Fairfax Water’s total chromium test results, view our Water Quality Analytical Reports by clicking here.

Beginning in January 2011, Fairfax started testing quarterly for hexavalent chromium in the drinking water. As the data becomes available, we will share that information with you.

Fairfax Water is committed to delivering a safe, high-quality water to our customers. To that end, Fairfax Water stands ready to respond to direction from the EPA regarding hexavalent chromium.