Probable Cancer-causing Chemical Found in Drinking Water of 31 of 35 U.S. Cities Tested (Updated)

Hexavalent chromium, the chemical made famous by the 2000 movie Erin Brockovich, is in the news again because a U.S. environmental organization detected the probable carcinogen in 31 of the 35 cities where it tested the drinking water. Environmental Working Group found concentrations of chromium in public drinking water supplies that ranged from 1/2 to 200 times what would be allowable by the state of California if a proposed chromium safety limit goes into effect.

Update 12/20 – The full report is available on the Environmental Working Group website. EWG has also posted tips for consumers and a frequently asked questions list that is summarized below.

Chromium is found in several chemical forms in mineral deposits in rock around the world. It is used in many industrial an manufacturing processes such as chrome plating and as an additive to steel to make it stainless. Hexavalent chromium, which is also known as chromium 6, is used in dying fabric, tanning leather, manufacturing magnetic tape, and preventing corrosion in a variety of industrial applications.

Pacific Gas & Electric, the company investigated and sued by Erin Brockovich on behalf of families in Hinkley, CA, in the early 1990s, was using the chemical to prevent rust in its equipment and discharging it into holding ponds on PG&E property, where it ultimately seeped into the drinking water.

One form of chromium, in small amounts, is actually considered a nutrient that is good for us: chromium 3 or trivalent chromium. Trace amounts of that form of chromium is essential for human metabolism and you may find it in your multivitamin. However, chromium 6 was officially classified as a probable carcinogen by the National Institutes of Health in 2009.

That classification prompted the Environmental Protection Agency and the state of California to reconsider drinking water safety standards for the chemical. The federal standard for levels of all types of chromium in drinking water is 100 parts per billion (ppb), approximately the same concentration as chromium occurs in the earth’s crust. California is considering a safety standard for chromium 6 at only 0.06 ppb. A full 25 of the 35 cities tested had drinking water concentrations higher than that proposed standard.

The 10 highest concentrations found by EWG of hexavalent chromium in drinking water:

  • Norman, OK – 12.90 ppb
  • Honolulu, HI – 2.00 ppb
  • Riverside, CA – 1.69 ppb
  • Madison, WI – 1.58 ppb
  • San Jose, CA – 1.34 ppb
  • Tallahassee, FL – 1.25 ppb
  • Omaha, NE – 1.07 ppb
  • Albuquerque, NM – 1.04
  • Pittsburgh, PA – 0.88
  • Bend, OR – 0.78

(Added 12/20) According to previous work by EWG, at least 74 million people in nearly 7,000 communities drink tap water polluted with “total chromium,” which includes hexavalent and other forms of the metal. The U.S. EPA does not require utilities to test for chromium-6, consequently, EWG’s report is the most comprehensive data public ally available.

“Every single day, pregnant mothers in Norman, Oklahoma, school children in Madison, Wisconsin, and many other Americans are drinking water laced with this cancer-causing chemical,” said EWG senior scientist Rebecca Sutton, Ph.D., in a press release. “If the EPA required local water utilities to test for hexavalent chromium, the public would at least know if it was present in their local water. Without mandatory tests and a safe legal limit that all utilities must meet, many of us will continue to swallow some quantity of this carcinogen every day.”

In the same release, Brockovich was quoted saying, “It is sometimes difficult to understand why I still have to warn the public about the presence of hexavalent chromium in drinking water 23 years after my colleagues and I first sounded the alarm. This report underscores, in fairly stark terms, the health risks that millions of Americans still face because of water contamination.”

Avoiding Chromium-6 in Your Drinking Water

  • Find out what’s in your water – Consumers who’s cities are listed in EWG’s database on tap water contaminants can use it to determine if their water supply has reported high levels of total chromium. High levels of total chromium often, but not always, mean high levels of chromium-6. Otherwise, you can request a water quality report from your local utility or get your private well tested.
  • Filter your tap water but don’t switch to bottled water – EWG recommends a whole-house reverse osmosis water filter, which removes most contaminants. The group publishes a guide for buying a water filter but does not recommend bottled water because water testing standards for bottlers is more lax than even tap water.

Read EWG’s full list of tips for consumers and frequently asked questions.

Drinking fountain image by flickr user Darwin Bell


criss S.
criss s6 years ago

thank you for the article.

Elizabeth M.
Elizabeth M7 years ago

Thanks for the information Jennifer, although it is not good news for thousands of people in the US. Brockovich rang the warning bell 23 years ago on hexavalent chromium and still it is going on?????

Loesje vB
Loesje Najoan7 years ago

Just hope the people in US knows about this scary info.

Michael R.
Michael R.7 years ago

Why would the PTB put expensive, rare-earth nonovalent chromium into our drinking water when they've been killing US all off for 65 years with the cheapest-industrial-grade Sodium Fluoride?

Jennifer H.
Jennifer H.7 years ago

I have many health problems and have gotten at least a little better since I stopped drinking tap water, started taking vitamins, and started eating healthy. I thought I was eating healthy before, but I was seriously miss informed. I won't let my kids drink tap water either, and have caught ridicule from my neighbors for my attention to what I put in my body and for educating my kids about what they put in theirs. "Well MOST people don't care if their kids drink tap water and eat mcdonalds." Well that's fine I feel sorry for their kid's future. They sit here telling my that mile long factory across the street pumping huge amounts of pollution into the air isn't hurting their kids. Give me a break Clinton, Iowa. So I guess it's just a coincidence that handing out nebulizers to all the newborns is common practice here. Or that the ratio of mental handicapped persons here is so high. The blind actions of the parents here is so unfair to the children who rely on them to make decisions that affect their health and their future. I think I will just keep protecting my kids and helping spread the word to people who are open to change. Thanks for spreading the word. I'm surprised people didn't know this. You would be surprised at what else is in your water.

Garret McCarty
Garret McCarty7 years ago


Brenda Marie C. C.

Why is the government allowing this? is it b/c people want less government intervention into their lives, i.e smaller government.
We must make up our minds what we want, I guess the people at the top have water filters on their showers, and faucets.
This article is a wonderful reminder of taking care of our selves while we push forward to making our world a better place,
Thanks again for the informative post.

Barbara Erdman
Barbara Erdman7 years ago

Thanx for info :-0

ilse D.
.7 years ago

thank you for the info, I dont live in the USA but over here some cities got posoined water as well. Which suprised me since it should be controlled daily ..

michael c.
corbin m7 years ago

See, it's not even about global warming. It's about what you eat, drink, swim in. Leave it to conservatives to deny, deny, deny-ANYTHING, if it deeps them from ever admitting they're wrong.