Chromium-6 (Hexavalent Chromium)
A toxic form of chromium made famous by the Erin Brockovich case. Can occur naturally or from industrial pollution.
Source
Industrial discharge, natural erosion, and coal-burning power plants.
Health Risk
When ingested, linked to stomach cancer in animal studies. California has proposed a stricter limit than the federal EPA.
Filter Tip
Reverse osmosis and strong-base anion exchange filters can reduce chromium-6.
Chromium-6 (hexavalent chromium) is the toxic form of chromium made famous by the Erin Brockovich case, in which it contaminated drinking water in Hinkley, California. It can occur naturally in groundwater or come from industrial pollution.
The federal EPA has a limit of 100 ppb for total chromium (both chromium-3 and chromium-6 combined), but no separate standard for chromium-6 alone. California set its own limit of 10 ppb for chromium-6 in 2014, though it was later withdrawn due to a legal challenge.
Why Is Chromium-6 Dangerous?
While chromium-3 is an essential nutrient, chromium-6 is a known carcinogen when inhaled and a probable carcinogen when ingested. Health concerns include:
- Stomach and intestinal cancer when ingested in drinking water (shown in animal studies)
- Liver and kidney damage
- Reproductive harm
- Allergic dermatitis
How Does Chromium-6 Get Into Water?
Chromium-6 enters drinking water through natural erosion of chromium deposits (common in the western US), industrial discharge from chrome plating and manufacturing, coal ash from power plants, and improperly disposed industrial waste.
How to Remove Chromium-6
- Reverse Osmosis: Very effective at removing chromium-6
- Strong-Base Anion Exchange: Designed specifically for chromium-6 removal
- Specialized Ion Exchange: Some systems are tailored for hexavalent chromium
Standard activated carbon filters are NOT effective for chromium-6. Ensure your filter is specifically certified for chromium reduction.
Chromium-6 (Hexavalent Chromium) Levels in US Cities
Based on verified municipal water quality reports (Consumer Confidence Reports) from 4 cities.
Frequently Asked Questions
Is chromium-6 the Erin Brockovich chemical?
Yes. Chromium-6 (hexavalent chromium) is the contaminant from the Erin Brockovich case in Hinkley, California. Pacific Gas & Electric contaminated the groundwater with chromium-6 from cooling tower operations.
Is there a federal limit for chromium-6?
Not specifically. The EPA limit of 100 ppb applies to total chromium (chromium-3 + chromium-6 combined). California attempted to set a separate 10 ppb limit for chromium-6. Environmental groups have called for a federal standard.
How common is chromium-6 in drinking water?
A 2016 study by the Environmental Working Group found chromium-6 in the drinking water of all 50 states, affecting over 200 million Americans. Most levels were below the EPA total chromium limit but above the levels some scientists consider safe.
Related Contaminants
Arsenic
A naturally occurring element found in rock and soil that can dissolve into groundwater.
Lead
A toxic heavy metal that typically enters drinking water through corroding pipes, faucets, and solder — not from the water source itself.
Copper
A metal that enters water primarily through corrosion of household copper plumbing.