Chromium III vs. Chromium VI in Water: What You Need to Know

Child Drinking WaterRecent reports have indicated the presence of chromium vi, also known as hexavalent chromium, in the municipal water supplies of 31 cities across the U.S. This toxic compound is an industrial pollutant and is known to be carcinogenic. Currently, the most effective way to remove chromium-6 from water is reverse osmosis filtration.

However, yearly water quality reports fail to distinguish between chromium vi and chromium iii. While the former is toxic and cancer-causing, the latter is an essential nutrient that is biologically active and found in everyday foods. Chromium-3 or trivalent chromium, is known to enhance the action of insulin, a hormone needed to metabolize and store carbohydrate, fat and protein in the body. Researchers have investigated the effect of chromium-3 supplements on preventing the onset of type-2 diabetes, and though these studies are inconclusive, there is no doubt that trivalent chromium is an essential and healthy compound. Failing to distinguish between hexavalent chromium and trivalent chromium is, as one report notes, like “lump[ing] a known carcinogen in with a vitamin.”

The moral of the story? Make sure you test your water for hexavalent chromium, specifically. Since chromium iii is found in so many foods, removing it from your water, along with chromium vi, is likely inconsequential. Most water filters that remove hexavalent chromium are likely to remove trivalent chromium as well, and it’s worth removing both in order to reduce your exposure to chromium-6. But simply buying a water filter that claims to remove “chromium,” but does not specify which type, may end up doing you no good, if your goal is to reduce the toxic variety.

The good news is, since the discovery of chromium-6 in water supplies across the U.S., health officials have recognized the importance of specifying these details on yearly water reports and will likely do so, in order to ensure a higher level of reliability in the future.

Hexavalent Chromium prompts Tap Water Safety concerns

Hexavalent Chromium in US Tap Water

If you’ve heard anything about hexavalent chromium in tap water, it was probably from the movie Erin Brockovich. In that film, the legal clerk and environmental activist Erin Brockovich (as played by Julia Roberts) built a case against California’s Pacific Gas and Electric litigation alleging that the cancer-causing hexavalent chromium the company was using to fight corrosion in cooling towers had seeped into the ground water of Hinkley, California.

Since settling that case in 1996, Brockovich has continued to work on cases involving hexavalent chromium. Just last year, she began investigating a case in Midland, Texas and assisted in filing a lawsuit against Prime Tanning Corp. of St. Joseph, Missouri. And if recent tests are any indication, Erin Brockovich and others like her might soon be swamped with similar cases.

Recent laboratory tests commisioned by the Environmental Working Group have found hexavalent chromium in the tap water of 31 cities. More disturbing still is the fact that the tap water from only 35 cities was sampled for the cancer-causing chemical, meaning it was found in 89 percent of the cities tested. The EWG estimates that 74 million Americans in 42 states could be drinking tap water that is polluted with chromium or its carcinogenic form, hexavalent chromium.

Hexavalent chromium is also known as Chromium-6 or Chromium (VI), though many refer to it as the “Erin Brockovich chemical”. It is the cancer-causing variant of chromium. The Environmental Protection Agency  allows for 100 parts per billion of total chromium in drinking water, but it has not set a safe or acceptable limit for hexavalent chromium. As such, water utility companies are not required to test for hexavalent chromium. California is the only state that requires such testing, and it has set a legal limit of .06 parts per billion. Of the 31 cities that had hexavalent chromium, 25 cities had levels higher than that amount.

However, there is no set limit for chromium-6, and water utility companies are not required to test for it. California is the only state that mandates testing, and that state’s legal limit for chromium-6 in drinking water is .06 ppb. Sutton and her colleagues found that 25 of the 31 cities with chromium-6 contaminated water had levels higher than that amount.

In an ideal world, the EPA would set legal limits for every state and require that water utilities test to ensure hexavalent chromium doesn’t enter our tap water. But as Erin Brockovich knows all too well, we don’t live in an ideal world. So how do you remove hexavalent chromium from tap water? Many reverse osmosis systems will remove chromium-6, as well as other contaminants.

Our Pentek RO-3500 Reverse Osmosis System reduces 86.6 percent of hexavalant chromium and 92.8 percent of trivalent chromium. What a RO system removes or reduces depends entirely on the filters and membranes used. We do carry many reverse osmosis membranes that reduce hexavalent chromium, so if you have an existing RO system and want to ensure you reduce chromium-6, please give us a call at 866-438-3458 or e-mail us at

Not sure if you should be concerned? Our eXact Micro 7+ Standard Photometer Kit allows you to test water for hexavalent chromium and many other contaminants.