What is Chromium (total)* and Why Does It Matter?

Chromium is a naturally occurring metal found in rocks, soil, and groundwater across the United States. It exists in several chemical forms, but two matter most for drinking water: trivalent chromium (chromium-3) and hexavalent chromium (chromium-6). Chromium-3 is relatively harmless and even an essential nutrient in tiny amounts. Chromium-6 is the dangerous one — it's a known carcinogen linked to cancer in humans and animals. Industrial sources like metal plating facilities, leather tanneries, and coal ash pits release chromium-6 into the environment. From there, it seeps into groundwater and eventually reaches your tap. Natural erosion of chromium-rich rock deposits also contributes, which is why some regions see elevated levels with no industrial cause at all.

The health risks depend heavily on how much chromium you're exposed to and for how long. At low levels, short-term exposure is unlikely to cause immediate harm. Long-term exposure is a different story. The International Agency for Research on Cancer (IARC) classifies hexavalent chromium as a Group 1 carcinogen — meaning there is strong evidence it causes cancer in humans, particularly stomach cancer when ingested through drinking water. The Environmental Working Group (EWG) estimates that chromium-6 in tap water may be responsible for thousands of additional cancer cases across the U.S. over a lifetime of exposure. Children, pregnant women, and people with weakened immune systems face the greatest risk from ongoing low-level exposure.

Here's where the regulatory picture gets frustrating. The EPA's current legal limit for total chromium in drinking water is 100 parts per billion (ppb). That standard was set in 1991 and hasn't been updated since, despite decades of new research on chromium-6 specifically. The EWG's health guideline for chromium-6 is just 0.02 ppb — 5,000 times more protective than the EPA's limit. The data shows total chromium appearing in 1,423 water systems nationwide, with an average detected level of 1.858 ppb. The maximum recorded level hits 431 ppb — more than four times the EPA's legal limit. Only 1 system currently exceeds the EPA guideline, but that number looks very different when measured against the EWG's science-based threshold.

Geographically, chromium shows up most often in Texas (227 systems), Kansas (197 systems), Arkansas (127 systems), West Virginia (97 systems), and New York (94 systems). Texas and Kansas sit on top of vast aquifer systems that pass through naturally chromium-rich geology, which partly explains their high detection rates. West Virginia's numbers reflect its long industrial history — mining, chemical manufacturing, and coal processing have all left their mark on the state's groundwater. New York's detections are more scattered, tied to a mix of aging industrial sites and natural mineral deposits. In general, states with heavy agricultural activity, active mining, or significant industrial infrastructure tend to see higher chromium levels in their water supplies.

The good news is that chromium — including the dangerous hexavalent form — is very effectively removed by the right filtration technology. Reverse osmosis (RO) systems are the gold standard here. A quality RO system removes up to 99% of total chromium from drinking water, bringing levels well below even the EWG's strict health guideline. Activated alumina filters and strong-base anion exchange systems also reduce chromium-6 significantly. Standard carbon filters and basic pitcher filters, however, do not reliably remove chromium — so checking your filter's certified performance data matters. Echo Water's reverse osmosis systems are independently tested and certified to remove chromium along with dozens of other contaminants, giving you water that meets the most protective health standards available. If you're in Texas, Kansas, or any of the other high-detection states, testing your tap water first is a smart move. Knowing your actual levels helps you choose the right solution — and gives you real peace of mind instead of just guesswork.

Regulatory Standards for Chromium (total)*

Cities With the Highest Chromium (total)* Levels

States Most Affected by Chromium (total)*

Frequently Asked Questions

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