What Does Chromium-6 Do to Your Body — And Is It in Your Water?

The Erin Brockovich Chemical Is Still in Your Water

If you have seen the film *Erin Brockovich*, you know the story: a California town, a contaminated water supply, and a chemical called hexavalent chromium — chromium-6 — at the center of it all. That was the 1990s. The problem has not gone away.

According to the Environmental Working Group, chromium-6 now contaminates the drinking water of more than 200 million Americans across all 50 states, Puerto Rico, the Northern Mariana Islands, and Guam. More than 8,600 water utilities have detected it. And the federal legal limit — set in 1991 based on skin irritation, not cancer risk — has not been updated to reflect what scientists now know about this chemical.

Understanding what chromium-6 is, what it does to your body, and how to remove it from your water is not a matter of alarmism. It is a matter of being informed.

What Is Chromium-6?

Chromium is a naturally occurring metallic element found in rocks, soil, and volcanic dust. It exists in several chemical forms, but two are most relevant to human health: trivalent chromium (chromium-3) and hexavalent chromium (chromium-6).

Chromium-3 is an essential trace nutrient that the body uses in small amounts to help regulate blood sugar. It is found in many foods and is not considered a health hazard at typical dietary levels.

Chromium-6 is a different matter entirely. It is produced by industrial processes — including the manufacturing of stainless steel, chrome plating, leather tanning, and the production of dyes and pigments — and it can also occur naturally from the erosion of chromium-bearing rock formations. Unlike chromium-3, hexavalent chromium is a potent oxidizing agent that is highly reactive in biological tissue.

The two forms can interconvert under certain conditions, but chromium-6 is far more toxic and far more mobile in the environment than chromium-3. Once it enters groundwater or a surface water supply, it travels freely and persists.

What Chromium-6 Does to Your Body

The health effects of chromium-6 exposure depend on the dose, the duration of exposure, and the route of exposure (ingestion, inhalation, or skin contact). For drinking water, ingestion is the primary concern.

Cancer is the most serious documented health effect. The National Toxicology Program found significant increases in stomach and intestinal tumors in laboratory animals given chromium-6 in drinking water. California scientists reported elevated stomach cancer risk in workers exposed to chromium-6. The EPA's own draft health assessment, published in 2010, concluded that even relatively low doses of chromium-6 in drinking water could increase cancer risk.

California's Office of Health Hazard Assessment set a public health goal for chromium-6 in tap water at 0.02 parts per billion — the level expected to cause no more than one additional cancer case per million people over a lifetime of exposure. The current federal legal limit for total chromium is 100 parts per billion — 5,000 times higher than California's health-based goal.

Beyond cancer, chronic chromium-6 exposure has been linked to:

• Liver and kidney damage — the liver and kidneys are the primary organs responsible for processing and excreting chromium, and they bear the brunt of chronic exposure
• Reproductive harm — animal studies have shown effects on fertility and fetal development at elevated doses
• Immune system disruption — chromium-6 can interfere with normal immune function
• Gastrointestinal effects — nausea, stomach pain, and ulcers have been reported with high-level exposure

Certain populations are considered at higher risk: infants and young children (due to higher water intake relative to body weight), individuals with impaired liver function, and people who take antacids regularly (antacids raise stomach pH, which may reduce the conversion of chromium-6 to the less toxic chromium-3 in the stomach).

Where Is Chromium-6 Contamination Worst?

Chromium-6 has been detected in water supplies across all 50 states, but contamination is not evenly distributed. The states with the highest reported levels include:

The EWG's interactive tap water database allows you to search by ZIP code to see whether chromium-6 has been detected in your local water supply and at what concentration. Because the federal legal limit is for total chromium — not specifically chromium-6 — many utilities do not separately report hexavalent chromium levels, even when it is the dominant form present.

The Regulatory Gap

The disconnect between the science on chromium-6 and the regulatory response is one of the clearest examples of how federal drinking water standards can lag behind current health research.

The EPA's current legal limit of 100 ppb for total chromium was set in 1991 and is based on the risk of allergic dermatitis — a skin reaction — not cancer. California attempted to set a specific standard for chromium-6 at 10 ppb, but that standard was struck down in court in 2017 after a legal challenge from the chemical industry.

The EPA has been working on a separate chromium-6 standard for years. In the meantime, the legal limit that your utility is required to meet was written before the cancer research that now defines our understanding of this chemical.

This is why the EWG database is valuable: it compares your water not just to the outdated federal legal limit, but to health-based guidelines that reflect current science.

How to Remove Chromium-6 from Your Drinking Water

The good news is that chromium-6 can be effectively removed from drinking water with the right filtration technology. Not all filters work equally well, so it is important to choose a system certified for chromium-6 reduction.

Reverse osmosis (RO) is the most effective point-of-use technology for chromium-6 removal. A properly functioning RO system can remove 85–95 percent of chromium-6 from drinking water. Look for systems certified to NSF/ANSI Standard 58.

Strong-base anion exchange resins are highly effective at removing chromium-6 and are often used in whole-house systems. These resins attract and bind chromium-6 ions, removing them from the water stream.

Coagulation and filtration — the process used by many municipal water treatment plants — can reduce chromium-6 levels, but the efficiency varies and it is not typically sufficient to reach health-based guidelines.

Standard activated carbon filters (including pitcher filters and basic under-sink filters) are not effective at removing chromium-6. If your primary concern is chromium-6, a standard Brita or similar pitcher filter will not address it.

Whole-house filtration systems that incorporate anion exchange or reverse osmosis technology provide the most comprehensive protection, treating all water that enters your home — including shower and bath water, where chromium-6 can be absorbed through skin and inhaled as steam during hot showers.

When evaluating any filter for chromium-6 removal, look for NSF/ANSI certification specifically for hexavalent chromium (chromium-6), not just total chromium. The two are different, and a filter certified for one may not be certified for the other.

The Bottom Line

Chromium-6 is a known carcinogen present in the drinking water of more than 200 million Americans. The federal legal limit was set in 1991 and does not reflect the cancer research that has accumulated since then. If you live in a high-risk area — or simply want to know whether chromium-6 has been detected in your local water supply — the EWG database is the place to start.

For households where chromium-6 is a concern, a whole-house filtration system with anion exchange or reverse osmosis technology is the most comprehensive solution. It treats every tap in your home, not just the kitchen sink, and provides continuous protection rather than requiring you to remember to use a specific filtered tap.

Want to know if chromium-6 is in your water? Get your free personalized water report from FranklyH2O. We pull the latest EPA data for your ZIP code and flag the contaminants that matter most for your area.

Sources: Environmental Working Group (EWG), U.S. Environmental Protection Agency (EPA), National Toxicology Program (NTP), California Office of Health Hazard Assessment (OEHHA), NSF International.